博士(工学) 課程 早稲田大学 デバイス関連化学
International Society of Electrochemistry
The Electrochemical Soc.（米国電気化学会）
化学 / 材料化学 / デバイス関連化学
Yunwen Wu, Takuya Jin, Toshiyuki Momma, Tokihiko Yokoshima, Hiroki Nara, Tetsuya Osaka
Journal of Power Sources399(7)p.287 - 2932018年09月-
概要：The usage of Li metal in lithium sulfur (Li-S) battery has largely hampered the application of Li-S battery due to the formation of Li dendrite during cycling. Here, a novel potentiostatic (p-stat) lithiation method was developed to fabricate Li2Sx cathode. The pre-lithiated Li2Sx cathode can be used to pair with the Li metal free anode to make a full cell with better safety. The dissolution of the polysulfide in electrolyte is the main problem in S cathode, which leads to severe active material loss during lithiation process. Normally, the way to alleviate the dissolution of polysulfide is by trapping the polysulfide from diffusing into the electrolyte. In this work, it is innovatively raised the p-stat lithiation method which can suppress the formation of polysulfides. As a result, dissolution of polysulfide species could be kinetically suppressed. The p-stat lithiated Li2Sx cathode exhibits higher capacity performance (around 400 mAh g−1) than the galvanostatic (g-stat) lithiated Li2Sx cathode. The Li metal free full cell assembled by pairing p-stat lithiated Li2Sx cathode with graphite anode shows stable cyclability.
Yunwen Wu, Toshiyuki Momma, Tokihiko Yokoshima, Hiroki Nara, Tetsuya Osaka
Journal of Power Sources388(6)p.5 - 102018年06月-
概要：Sulfur (S) Li-ion battery which use the metallic Li free anode is deemed as a promising solution to conquer the hazards originating from Li metal. However, stable cycling performance and low production price of the S Li-ion battery still remain challenging. Here, we propose a S-LixC full cell system by paring a S cathode and a pre-lithiated graphite anode which is cheap and commercially available. It shows stable cycling performance with a capacity around 1300 mAh (g-S)−1 at 0.2 C-rate and 1000 mAh (g-S)−1 at 0.5 C-rate. In addition, 0.1% per cycle capacity fading rate with a capacity retention of 880 mAh (g-S)−1 after 400 cycles at 0.2 C-rate has been achieved. The pre-formed solid electrolyte interphase (SEI) layer on the pre-lithaited graphite anode largely contributes to the high capacity performance. Notably, a 10-times-enlarged scale of S-LixC laminate type full cell has been assembled with high capacity performance (around 1000 mAh (g-S)−1) even after high rate cycling.
Togasaki, Norihiro; Shibamura, Ryuji; Naruse, Takuya; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya; Osaka, Tetsuya
概要：© 2018 Author(s). Among the recent advancements in lithium-oxygen (Li-O 2 ) chemistries, redox mediators (RMs) have been revealed to play a significant role in decreasing overpotential on charging and in improving cycling performance. However, an intrinsic problem is redox shuttle of RMs, which leads to degraded RM utilization and induces the accumulation of discharge products on the cathode surface; this remains a significant issue in the current battery cell configuration (Li anode/separator/cathode). To address this detrimental problem, herein we propose a novel Li-O 2 cell incorporating a freestanding electropolymerized polypyrrole (PPy) film for the restriction of the redox-shuttle phenomenon of lithium iodide (Li anode/separator/PPy film/cathode). In this study, a PPy film, which is prepared through oxidative electropolymerization using an ionic liquid of 1-methyl-1-butylpyrrolidinium mixed with pyrrole and lithium bis(trifluoromethanesulfonyl)imide, is introduced between the cathode and the separator. From the charge-discharge voltage profile, it is confirmed that the PPy film suppresses the diffusion of the oxidized I 3 - to the Li anode, while allowing Li ion transport. Secondary scanning electron microscope measurements confirm that the chemical reactions between I 3 - and Li 2 O 2 are facilitated by the presence of the PPy film because I 3 - remains near the cathode surface during the charging process. As a result, the cycling performance in the Li-O 2 cells with PPy film exhibits a cycling life four times as long as that of the Li-O 2 cells without PPy film.
Hiroki Nara, Daikichi Mukoyama, Ryo Shimizu, Toshiyuki Momma, Tetsuya Osaka
Journal of Power Sources2018年01月-
概要：Lithium-ion batteries are required to have high-power density, that is to reduce impedance, for use in electric vehicles. This paper focuses on interfacial resistance between the cathode layer (CL) and the current collector (CC) observed at high frequencies, which is generally attributed to a resistance of surface film like SEI. To investigate the interfacial resistance systematically, different interfaces between the CL and the CC were prepared by controlling the press rate for the cathode preparation, or by introducing a carbon under-coating layer (CUL), followed by electrochemical impedance spectroscopy (EIS). The interfacial resistance between the CL and the CC prepared with an insufficient press rate or without a CUL was extremely high for the entire cathode. From the cathode cross-sectional observation, it was observed that this high interfacial resistance was caused by low contact rate at the interface. Using a pouch-type symmetric cell, EIS revealed that the interfacial resistance is attributed to electric resistance, that is, contact resistance at the interface. Also, the other resistances were attributed to be the ionic resistance of the electrolyte and pores in the cathode, and the charge transfer resistance of the cathode. Furthermore, the effectiveness of the CUL was shown to decrease the cathode impedance.
Nara, Hiroki; Mukoyama, Daikichi; Shimizu, Ryo; Momma, Toshiyuki; Osaka, Tetsuya
Journal of Power Sources2018年01月-2018年01月
Matsuda, Shofu; Nakajima, Eri; Nakanishi, Takuya; Hitsuji, Airi; Zhang, Hong; Tanaka, Akane; Matsuda, Hiroshi; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya; Osaka, Tetsuya
Materials Science and Engineering C81p.90 - 962017年12月-2017年12月
概要：© 2017 Elsevier B.V. With the objective of finding an avenue for development of magnetic hyperthermia as an effective mesothelioma treatment, the influence of heating by magnetite nanoparticles (MNPs) with a diameter of ~ 40 nm, which were incorporated into cells and then subjected to AC magnetic field, on induction of cell death was investigated in all three histological subtypes of human mesothelioma cells (i.e., epithelioid NCI-H28, sarcomatoid NCI-H2052, and biphasic MSTO-211H cells). Cellular uptake of MNPs was observed in all cell types, but the amount of MNPs incorporated per cell into MSTO-211H cells was smaller than in NCI-H28 and NCI-H2052 cells. On the other hand, cell death induced by cellular uptake of MNPs was observed specifically in MSTO-211H cells. Hence, when cells are heated by intracellular MNPs under AC magnetic field, a high degree of cell mortality in NCI-H28 and NCI-H2052 cells is induced by the temperature increase derived from the high amount of intracellular MNPs, but the combination of intracellular heating and cell-type-specific toxicity of MNPs induced high rates of cell death in MSTO-211H cells even at a lower temperature. Almost all of the heated cells were dead after 24-h incubation at 37 °C in all histological subtypes. Additionally, higher mortalities were observed in all three types of mesothelioma cells after MNPs-heating, as compared to the heating with a thermostatic bath. Herein, the significance of cellular uptake of MNPs for effectively inducing cell death in mesothelioma has been demonstrated in vitro.
Wu, Yunwen; Momma, Toshiyuki; Momma, Toshiyuki; Ahn, Seongki; Yokoshima, Tokihiko; Nara, Hiroki; Osaka, Tetsuya; Osaka, Tetsuya
Journal of Power Sources366p.65 - 712017年10月-2017年10月
概要：© 2017 The Authors This work reports a new chemical pre-lithiation method to fabricate lithium sulfide (Li 2 S) cathode. This pre-lithiation process is taken place simply by dropping the organolithium reagent lithium naphthalenide (Li + Naph − ) on the prepared sulfur cathode. It is the first time realizing the room temperature chemical pre-lithaition reaction attributed by the 3D nanostructured carbon nanotube (CNT) current collector. It is confirmed that the Li 2 S cathode fabricated at room temperature showing higher capacity and lower hysteresis than the Li 2 S cathode fabricated at high temperature pre-lithiation. The pre-lithiated Li 2 S cathode at room temperature shows stable cycling performance with a 600 mAh g −1 capacity after 100 cycles at 0.1 C-rate and high capacity of 500 mAh g −1 at 2 C-rate. This simple on-site pre-lithiation method at room temperature is demonstrated to be applicable for the in-situ pre-lithiation in a Li metal free battery.
Kowase, Takayuki; Hori, Keisuke; Hasegawa, Kei; Momma, Toshiyuki; Noda, Suguru; Noda, Suguru
Journal of Power Sources363p.450 - 4592017年09月-2017年09月
概要：© 2017 Elsevier B.V. Rapid gas-evaporation method is proposed and developed, which yields Si nanoparticles (SiNPs) in a few seconds at high yields of 20%–60% from inexpensive and safe bulk Si. Such rapid process is realized by heating the Si source to a temperature ≥2000 °C, much higher than the melting point of Si (1414 °C). The size of SiNPs is controlled at tens to hundreds nanometers simply by the Ar gas pressure during the evaporation process. Self-supporting films are fabricated simply by co-dispersion and filtration of the SiNPs and carbon nanotubes (CNTs) without using binders nor metal foils. The half-cell tests showed the improved performances of the SiNP-CNT composite films as anode when coated with graphitic carbon layer. Their performances are evaluated with various SiNP sizes and Si/CNT ratios systematically. The SiNP-CNT film with a Si/CNT mass ratio of 4 realizes the balanced film-based capacities of 618 mAh/g film , 230 mAh/cm 3 , and 0.644 mAh/cm 2 with a moderate Si-based performance of 863 mAh/g Si at the 100th cycle.
Yokoshima, Tokihiko; Mukoyama, Daikichi; Nara, Hiroki; Maeda, Suguru; Nakazawa, Kazuhiro; Momma, Toshiyuki; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya; Osaka, Tetsuya
Electrochimica Acta246p.800 - 8112017年08月-2017年08月
概要：© 2017 Elsevier Ltd Electrochemical impedance measurements of lithium ion batteries (LIBs) in energy storage systems (ESS) were performed. Square-current electrochemical impedance spectroscopy (SC-EIS), which is a simple and cost-effective approach to measure impedance, was chosen to investigate a large-scale LIB system. Harmonics calculated by Fourier transform from a square waveform were used to determine the impedance. On the basis of a simple electrochemical reaction involving the ferri/ferro-cyanide redox couple and the LIB, the accuracy of the impedance measurement was found to depend on both the signal-to-noise ratio of the power spectra of the harmonics as well as the attenuation rate of the “measured value of impedance” and the “theoretical spectra value” from Fourier series. The accuracy was improved by adjusting the input waveform to be close to an ideal square waveform from Fourier series. The accuracy was further improved by the combined use of a simple moving average and an overall average. The impedance from a degraded square waveform generated by a cost-effective power controller was able to be deter mined by increasing the measurement time, which aided averaging. By designing the input signal to be close to an ideal square waveform from Fourier series, kilowatt-class LIB modules/cubicles in an ESS was able to be measured. Moreover, a degraded LIB module in an ESS was able to be detected using EIS, which highlights the utility of this technique for in situ impedance measurements of large-scale LIB systems.
Nara, Hiroki; Morita, Keisuke; Mukoyama, Daikichi; Yokoshima, Tokihiko; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya; Osaka, Tetsuya
Electrochimica Acta241p.323 - 3302017年07月-2017年07月
概要：© 2017 Elsevier Ltd Mid to low frequency impedance for a cathode in a lithium ion battery (LIB), which is affected by lithium-ion diffusion into active materials, was investigated. We had earlier suggested that charge-transfer and diffusion impedances are attributed to a particle size distribution for a commercially available LIB, and we designed an equivalent circuit in which two series circuits of charge-transfer resistance and Warburg impedance were connected in parallel. Here, to validate the design of the equivalent circuit, the secondary-particle size distribution of the LiNi 1/3 Mn 1/3 Co 1/3 O 2 cathode in a lab-made LIB, in which the secondary-particles were controlled into wide and narrow distribution by sieving, was investigated by electrochemical impedance spectroscopy. The equivalent circuit was designed in which series circuits of charge-transfer resistance and Warburg impedance were connected in parallel. Dependency of impedance response on the number of parallels of the series circuits was evaluated for the cathodes using different secondary-particle size distributions of the active material. Additionally, the tendency of change in the charge-transfer resistance and the limiting capacitance was discussed from the standpoint of secondary-particle size distribution. The results confirm the effectiveness of the designed equivalent circuit which reflects the secondary-particle size distribution of cathode active materials.
Seko, Shohei; Nara, Hiroki; Jeong, Moongook; Yokoshima, Tokihiko; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya
Electrochimica Acta243p.65 - 712017年07月-2017年07月
概要：© 2017 Elsevier Ltd The cycle durability of electrodeposited Si-O-C composite anodes in glyme-based ionic liquid electrolytes, known as Li(G3)TFSI or Li(G4)TFSI (triglyme: G3 and tetraglyme: G4), which is one of the most promising electrolytes for sulfur cathode, was improved for use in lithium secondary batteries by using additives, fluoroethylene carbonate (FEC) or vinylene carbonate (VC). We revealed an importance of the activation process and the effects of additives in the Si-O-C composite anode. The capacity of the Si-O-C composite anode decreased with charge-discharge cycles in electrolytes without additives. Meanwhile, although the capacity retention in electrolytes with additives was improved by 10–20%, their initial capacity was smaller than those without additives. To solve the contradiction, an activation process, in which the Si-O-C composite anode was charged and discharged in electrolytes without additives, was introduced before charge-discharge cycles in electrolytes with additives. Owing to the optimized activation process, the initial capacity in electrolytes with additives showed as high as 1100–1300 mAh g −1 as those without additives with better capacity retention. Therefore, the necessity to adequately generate an activation reaction and to form SEI derived from additives for the Si-O-C composite anode to have better charge-discharge performance was demonstrated.
Wu, Yunwen; Yokoshima, Tokihiko; Nara, Hiroki; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya; Osaka, Tetsuya
Journal of Power Sources342p.537 - 5452017年02月-2017年02月
概要：© 2016 Elsevier B.V.Lithium metal free sulfur battery paired by lithium sulfide (Li2S) is a hot point in recent years because of its potential for relatively high capacity and its safety advantage. Due to the insulating nature and high sensitivity to moisture of Li2S, it calls for new way to introduce Li ion into S cathode besides the method of directly using the Li2S powder for the battery pre-lithiation. Herein, we proposed a pre-lithiation method to lithiate the polypyrrole (PPy)/S/Ketjenblack (KB) electrode into PPy/Li2S/KB cathode at room temperature. By this process, the fully lithiated PPy/Li2S/KB cathode showed facilitated charge transfer than the original PPy/S/KB cathode, leading to better cycling performance at high C-rates and disappearance of over potential phenomenon. In this work, the ion-selective PPy layer has been introduced on the cathode surface by an electrodeposition method, which can suppress the polysulfide dissolution from the cathode source. The lithium metal free full battery coupled by the prepared Li2S/KB cathode and graphite anode exhibited excellent cycling performance. Hence, we believe this comprehensive fabrication approach of Li2S cathode will pave a way for the application of new type lithium metal free secondary battery.
Nara, Hiroki; Yokoshima, Tokihiko; Mikuriya, Hitoshi; Tsuda, Shingo; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya; Osaka, Tetsuya
Journal of the Electrochemical Society164(1)p.A5026 - A50302017年01月-2017年01月
概要：© The Author(s) 2016. Published by ECS.Ahigh areal capacity lithium-sulfur batterymaking use of mass produced aluminum metal foam as a current collectorwas investigated. A sulfur/Ketjenblack (KB) composite was filled and deposited into the aluminum foam current collector via a predetermined filling procedure, resulting in high sulfur loading. The value for this loading was found to be 17.7 mg sulfur/cm2 by using carboxymethyl cellulose and styrene butadiene rubber (CMC + SBR) as a binder. An operating single-layer pouch-Type cell with an S/KBCMC+ SBR on Al foam cathode was created as a result of this synthesis and found to possess an unprecedentedly high areal capacity of 21.9 mAh/cm2. On the basis of the achieved areal capacity, the energy density of a theoretical lithium-sulfur battery was estimated with the assumption of an electrolyte/sulfur ratio of 2.7 μL/mg. This was calculated upon 100% of the pore volume in the S/KB-CMC + SBR on Al foam cathodes and polyolefin separator, along with the inclusion of the weights of the tabs for the current lead and pouch film packaging in the case of a seven-layer pouch-Type battery. With this calculation, it was determined that the creation of a lithium-sulfur battery with an energy density of greater than 200 Wh/kg is plausible.
Tochihara, Misako; Nara, Hiroki; Yokoshima, Tokihiko; Momma, Toshiyuki; Osaka, Tetsuya
Electrochemistry85(11)p.721 - 7272017年01月-2017年01月
Ahn, Seongki; Jeong, Moongook; Miyamoto, Koki; Yokoshima, Tokihiko; Nara, Hiroki; Momma, Toshiyuki; Osaka, Tetsuya
Journal of the Electrochemical Society164(2)p.A355 - A3592017年01月-2017年01月
Togasaki, Norihiro; Gobara, Tadayoshi; Momma, Toshiyuki; Osaka, Tetsuya; Numata, Tomoko
Journal of the Electrochemical Society164(9)p.A2225 - A22302017年01月-2017年01月
Matsuda Shofu;Nakajima Eri;Nakanishi Takuya;Hitsuji Airi;Zhang Hong;Tanaka Akane;Matsuda Hiroshi;Momma Toshiyuki;Osaka Tetsuya
Materials science & engineering. C, Materials for biological applications812017年-2017年
概要：:With the objective of finding an avenue for development of magnetic hyperthermia as an effective mesothelioma treatment, the influence of heating by magnetite nanoparticles (MNPs) with a diameter of ~40nm, which were incorporated into cells and then subjected to AC magnetic field, on induction of cell death was investigated in all three histological subtypes of human mesothelioma cells (i.e., epithelioid NCI-H28, sarcomatoid NCI-H2052, and biphasic MSTO-211H cells). Cellular uptake of MNPs was observed in all cell types, but the amount of MNPs incorporated per cell into MSTO-211H cells was smaller than in NCI-H28 and NCI-H2052 cells. On the other hand, cell death induced by cellular uptake of MNPs was observed specifically in MSTO-211H cells. Hence, when cells are heated by intracellular MNPs under AC magnetic field, a high degree of cell mortality in NCI-H28 and NCI-H2052 cells is induced by the temperature increase derived from the high amount of intracellular MNPs, but the combination of intracellular heating and cell-type-specific toxicity of MNPs induced high rates of cell death in MSTO-211H cells even at a lower temperature. Almost all of the heated cells were dead after 24-h incubation at 37°C in all histological subtypes. Additionally, higher mortalities were observed in all three types of mesothelioma cells after MNPs-heating, as compared to the heating with a thermostatic bath. Herein, the significance of cellular uptake of MNPs for effectively inducing cell death in mesothelioma has been demonstrated in vitro.
Togasaki, Norihiro; Momma, Toshiyuki; Osaka, Tetsuya
Journal of Power Sources307p.98 - 1042016年03月-2016年03月
概要：© 2015 Elsevier B.V. All rights reserved.Stable charge-discharge cycling behavior for a lithium metal anode in a dimethylsulfoxide (DMSO)-based electrolyte is strongly desired of lithium-oxygen batteries, because the Li anode is rapidly exhausted as a result of side reactions during cycling in the DMSO solution. Herein, we report a novel electrolyte design for enhancing the cycling performance of Li anodes by using a highly concentrated DMSO-based electrolyte with a specific Li salt. Lithium nitrate (LiNO3), which forms an inorganic compound (Li2O) instead of a soluble product (Li2S) on a lithium surface, exhibits a >20% higher coulombic efficiency than lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium perchlorate, regardless of the loading current density. Moreover, the stable cycling of Li anodes in DMSO-based electrolytes depends critically on the salt concentration. The highly concentrated electrolyte 4.0 M LiNO3/DMSO displays enhanced and stable cycling performance comparable to that of carbonate-based electrolytes, which had not previously been achieved. We suppose this enhancement is due to the absence of free DMSO solvent in the electrolyte and the promotion of the desolvation of Li ions on the solid electrolyte interphase surface, both being consequences of the unique structure of the electrolyte.
Nara, Hiroki; Mukoyama, Daikichi; Yokoshima, Tokihiko; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya; Osaka, Tetsuya
Journal of the Electrochemical Society163(3)p.A434 - A4412016年01月-2016年01月
概要：© The Author(s) 2015.Electrochemical impedance spectroscopy (EIS) using an equivalent circuit is a powerful tool in the diagnosis of lithium-ion batteries (LIBs). However, LIBs have been increasingly used in applications requiring power higher than that used for conventional LIBs for portable electric devices. Considering this demand for LIBs, the ionic resistances in the electrodes, which raise a reaction distribution under high-power operation, are important. This consequently means EIS analysis should include ionic resistances in the electrodes in equivalent circuits. Additionally, the impedance response of LIBs are too complicated to be analyzed in detail because the impedance response consists of overlapping elemental processes such as chemical reactions and ion migration. This paper therefore presents an analysis of impedance responses, which are independently obtained by a micro reference electrode, by using a transmission line model (TLM) that possesses the ability to count the ionic resistances in the electrodes. Similar to the conventional Randles equivalent circuit, the equivalent circuit with TLM could fit the impedance responses simulated by the equivalent circuit with measured responses. This paper discusses the potential of EIS using an equivalent circuit coupled with a TLM for diagnosis of LIBs in power applications.
Nara, Hiroki; Morita, Keisuke; Yokoshima, Tokihiko; Mukoyama, Daikichi; Momma, Toshiyuki; Osaka, Tetsuya
AIMS Materials Science3(2)p.448 - 4592016年01月-2016年01月
Nakamura, Natsuki; Wu, Yunwen; Yokoshima, Tokihiko; Nara, Hiroki; Momma, Toshiyuki; Osaka, Tetsuya
Journal of the Electrochemical Society163(5)p.A683 - A6892016年01月-2016年01月
Nara, Hiroki; Morita, Keisuke; Yokoshima, Tokihiko; Mukoyama, Daikichi; Momma, Toshiyuki; Osaka, Tetsuya
AIMS Materials Science3(2)p.448 - 4592016年01月-2016年01月
Jeong, Moongook;Ahn, Seongki;Yokoshima, Tokihiko;Nara, Hiroki;Momma, Toshiyuki;Osaka, Tetsuya
NANO ENERGY28p.51 - 622016年-2016年
概要：© 2016 Elsevier LtdThe poor electrical conductivity of Si-based anode materials is a critical challenge for the development of high-performance Li secondary batteries. We propose a new approach for enhancing the electrical conductivity of an electrodeposited Si–O–C composite anode via self-incorporation of nano Cu metal (n-Cu) using a facile and inexpensive electrochemical synthetic method. The Si–O–C composite with n-Cu (Cu/Si–O–C composite) shows stable cycle performance with a fairly high specific capacity. Since Cu precursor ions for the electrodeposition of n-Cu are directly dissolved from a Cu substrate used as the current collector for the anode, electrical conducting additives that causes increase in the weight and volume of the electrode are not unnecessarily supplemented. In the synthesis process, the n-Cu metal and Si–O–C composite are electrodeposited simultaneously. The n-Cu/Si–O–C composite anode results in improved electrochemical performance, including enhancement of areal and specific capacity; coulombic efficiency; and rate capability. Electrochemical impedance spectroscopy suggests that such improvements in performance are due to the enhanced electrical conductivity resulting from the conductive network of the incorporated n-Cu. Moreover, the electrical conductive properties of the incorporated n-Cu suppress electrochemical degradation of the n-Cu/Si–O–C composite anode.
Ahn, Seongki;Jeong, Moongook;Yokoshima, Tokihiko;Nara, Hiroki;Momma, Toshiyuki;Osaka, Tetsuya
JOURNAL OF POWER SOURCES336p.203 - 2112016年-2016年
概要：© 2016 Elsevier B.V.In this study, we report the preparation of carbon nanotubes (CNTs) anchor layer on a Cu substrate (CNTs/Cu) by using electrophoretic deposition technique. The CNTs anchor layer increases adhesion strength between Si-O-C composites and Cu substrate, as a result, it is possible to improve deposited Si amounts and areal capacity. The electrodeposited Si-O-C composites on CNTs/Cu (Si-O-C/CNTs/Cu) show homogenously coated surface morphology without cracks even large passing charge for electrodeposition of 15 C cm−2, resulting in 0.21 mg cm−2 of deposited Si amounts. On the other hand, Si-O-C composites deposited on as-received Cu substrate (Si-O-C/Cu) begin to peel off from substrate at 8 C cm−2 of passing charge, resulting in 0.13 mg cm−2 of deposited Si amounts, and decrease down to 0.10 mg cm−2 at 15 C cm−2 of passing charge. As a results, the improved Si amounts deposited on CNTs/Cu substrate achieve higher areal capacity, delivering 0.24 mA h cm−2, which attains increase in 84.6% in comparison to Si-O-C/Cu, which has areal capacity of 0.13 mA g cm−2 at 8 C cm−2 of passing charge. Moreover, the Si-O-C/CNTs/Cu shows improved anode performances including discharge capacity and C-rate performance of the Si-O-C composites than Si-O-C/Cu without CNTs anchor layer.
Yokoshima, Tokihiko;Mukoyama, Daikichi;Nakazawa, Kazuhiro;Gima, Yuhei;Isawa, Hidehiko;Nara, Hiroki;Momma, Toshiyuki;Osaka, Tetsuya
Electrochimica Acta180p.922 - 9282015年10月-2015年10月
概要：© 2015 Published by Elsevier Ltd. To realize electrochemical impedance spectroscopy (EIS) using a simple measurement system, application of a square potential/current waveform to the input signals of EIS was investigated. The impedance of a simple redox reaction of [Fe(CN)
Journal of Power Sources294p.588 - 5922015年07月-2015年07月
概要：© 2015 Elsevier B.V. All rights reserved. The effect of the solid electrolyte interphase (SEI) on a Li anode on the charge-discharge cycling performance in 1 M LiTFSI/dimethylsulfoxide electrolyte solution is examined by using charge-discharge cycling. The chemical structure of the surface and interior of the SEI strongly affects the cycling performance of the anode. The observed coulombic efficiency is low (<45%) when organic compounds such as lithium alkyl carbonates and polycarbonate form predominantly on the surface and interior. However, when inorganic compounds such as Li
Journal of Power Sources286p.540 - 5502015年07月-2015年07月
概要：© 2015 Elsevier B.V. All rights reserved. We report micrometre-thick porous Si-Cu anodes that are rapidly co-deposited on Cu current collectors in 1 min. This rapid deposition is realized by heating Si and Cu powders to ∼2000 °C and elevating their vapour pressures, while the porous and amorphous anode structure is realized by keeping the substrates at 100 °C. The films spontaneously form a 2-4.5-μm-thick composition gradient that changes from a Cu-rich region at the bottom to a Si-rich region at the top of the film, because of the higher vapour pressure for Cu than Si. A small addition of 5 wt% Cu to the Si source enhances the cycle performance of the film remarkably in a half-cell test, yielding a gravimetric capacity of 1250 mAh g
Chen, Chun Yi; Chen, Chun Yi; Yokoshima, Tokihiko; Yokoshima, Tokihiko; Nara, Hiroki; Nara, Hiroki; Momma, Toshiyuki; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya; Osaka, Tetsuya; Osaka, Tetsuya
Electrochimica Acta183p.78 - 842015年02月-2015年02月
概要：© 2015 Elsevier Ltd. Novel three-dimensional hierarchical heterostructures composed of two-dimensional SnS
Liu, Jun; Nara, Hiroki; Yokoshima, Tokihiko; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya; Osaka, Tetsuya
Electrochimica Acta183p.70 - 772015年02月-2015年02月
概要：© 2015 Elsevier Ltd. A facile and scalable method is proposed to prepare microscale Li
Journal of Power Sources275p.525 - 5302015年02月-2015年02月
概要：© 2014 Elsevier B.V. All rights reserved. The electrodeposited Sn-O-C composite anode cycling with LiClO4 delivered stable cycle performances showing discharge capacity of 473 mA h g of Sn -1 with 95% of coulombic efficiency at 100th cycle. However, the anode showed poor cycle performances with LiPF6 delivering discharge capacity of 69 mA h g of Sn -1 at 100th cycle with 70% of coulombic efficiency. Electrochemical investigation performed by cyclic voltammetry and differential capacity plots revealed that the Sn-O-C composite cycling with LiPF6 suffered from retarded phase transition reaction between Li and Sn during charge/discharge process. X-ray photoelectron spectroscopy declared the existence of fluorinated-Sn and LiF. Moreover, energy dispersive X-ray spectroscopy found increase in their amount with repeated cycles. The morphologies of the Sn-O-C composite cycled with LiPF6 showed aggregated particles containing the chemical state of fluorinated-Sn and LiF on its surface. Furthermore, the significant pulverization and aggregation of the active material were observed from the Sn-O-C composite cycled by LiPF6 rather than that of LiClO4, which was probably promoted by the generated HF strongly corroding metallic component.
Journal of the Electrochemical Society162(10)p.A2008 - A20152015年01月-2015年01月
概要：© The Author(s) 2015. The electrode surfaces of degraded lithium-ion batteries (LIB) were analyzed by liquid chromatography-quadrupole time of flight mass spectrometry (LC-QTOF/MS). The solid-electrolyte interphase (SEI) layer influences the performance of LIBs. Therefore, we conducted a study aimed at clarifying the deterioration mechanism of LIBs by examining the components in the SEI before and after degradation due to cycling.We believe that the change in the mass transfer characteristics at the electrode interface influenced by SEI deterioration can be clarified via LC-QTOF/MS, which would allow elucidation of the deterioration mechanism. The analysis results showed that the degradation products contain multiple components, including polymers of carbonate compounds and phosphate esters, which are formed via electrochemical and chemical reactions, resulting in remarkably reduced capacity. The results suggest that LC-QTOF/MS is a valuable technique for the degradation analysis of LIBs.
Journal of Power Sources274p.1263 - 12662015年01月-2015年01月
概要：© 2014 Elsevier B.V. In order to solve the problem of polysulfide dissolution into the electrolyte on sulfur-based cathodes, we propose a novel method of modifying the S cathode by coating it with a polypyrrole (PPy) film, which is prepared by oxidative electropolymerization using a solution consisting of, 1-methyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and pyrrole. The PPy film demonstrates a high Li+ transport number. The film also exhibits a superior ability to inhibit polysulfide dissolution into the electrolyte during the charge-discharge cycles. Furthermore, the charge-discharge properties of the coated cathode is evaluated using an electrolyte consisting of 1.0 M LiTFSI in a mixture of 1,2-dimethoxyethane (DME) and 1,3-dioxolane (DOL), which is known to easily dissolve polysulfides. Because of the surface modification with the PPy film, the cathode exhibits excellent specific capacities of 823 and 354 mAh g-1 at C-rates of 0.1 and 1.0 C, respectively, with high coulombic efficiency. Thus, the strategy of coating the S cathode with PPy is successful in inhibiting the polysulfides dissolution even in electrolytes known to easily dissolve polysulfides, besides allowing high C-rate operation. Further, the modification of the S cathode allows the selection of a suitable electrolyte based on the anode, rather than being limited by the cathode.
Journal of Power Sources273p.1136 - 11412015年01月-2015年01月
概要：© 2014 Elsevier B.V. All rights reserved. Polyvinylpyrrolidone (PVP) is used with polyethylene oxide (PEO) as a mixed binder for mechanically milled Li2S. PVP demonstrates its advantage in terms of increasing the capacity of Li2S, but boosts the potential barrier at the beginning of the first charge. It is also revealed that PVP retards the charge-transfer kinetics of Li2S. In Li2S-C prepared by mechanical milling, carbon compensates for the electrochemical insulation of the PVP binder and improves the cycle stability. As a result, the Li2S-C-PVP electrode with 60 wt% Li2S content displays a low potential barrier at the onset of charge and a stable capacity of about 460 mAh g-1 at 0.1 C.
Tochihara, Misako;Nara, Hiroki;Mukoyama, Daikichi;Yokoshima, Tokihiko;Momma, Toshiyuki;Osaka, Tetsuya
JOURNAL OF THE ELECTROCHEMICAL SOCIETY162(10)p.A2008 - A20152015年-2015年
Journal of Power Sources261p.23 - 272014年09月-2014年09月
概要：The effects of a small amount of H2O with and without CO 2 in an electrolyte of 1 M LiPF6/ethylene carbonate and diethyl carbonate on the cycling life of a Li metal anode is investigated in this paper using charge-discharge cycling. A low cycling performance, which is less than 55%, is observed with the electrolyte with trace H2O but without CO2; however, when the trace H2O is accompanied by CO2, performance drastically improves and coulombic efficiency reaches a maximum of 88.9%. In the presence of CO2, the cycling performance is found to be strongly affected by the H2O content in the electrolyte, and increases with an increase in H2O content of up to 35 ppm. From an X-ray photoelectron spectroscopy analysis, trace H 2O is found to affect the compounds of the solid electrolyte interphase (SEI) on the lithium surface and produces an Li2CO 3 and LiF layer on the upper part of the SEI, both known to be good passivation layers for preventing side reactions during charge-discharge cycling. © 2014 Elsevier B.V. All rights reserved.
Electrochimica Acta137p.41 - 482014年08月-2014年08月
概要：The nitrogen-doped carbon nanocapsules (NCNCs) were explored as catalyst support for oxygen reduction reaction (ORR) in acid electrolyte. The deposition of Pt particles on NCNCs support was characterized using various physico-chemical techniques, such as scanning electron microscope, transmission electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy. The high resolution transmission electron microscopy reveals that Pt particles are uniformly dispersed onto the NCNCs and particles size of about 2.2 nm was observed. The electrochemical ORR activities of the Pt supported on NCNCs catalysts were studied and compared with a commercial catalyst. Pt/NCNC showed enhanced ORR activity and better stability than a commercial Pt/C catalyst. The enhanced performance of Pt supported NCNCs can be attributed to the better dispersion and utilization of Pt nanoparticles. © 2014 Elsevier Ltd.
ACS Applied Materials and Interfaces6(14)p.10924 - 109282014年07月-2014年07月
概要：In this paper, we report a lithium-ion battery employing a lithium sulfide cathode and a silicon-based anode. The high capacity of the silicon anode and the high efficiency and cycling rate of the lithium sulfide cathode allowed optimal full cell balance. We show in fact that the battery operates with a very stable capacity of about 280 mAh g-1 at an average voltage of 1.4 V. To the best of our knowledge, this battery is one of the rare examples of lithium-metal-free sulfur battery. Considering the high theoretical capacity of the employed electrodes, we believe that the battery here reported may be of potential interest as high-energy, safe, and low-cost power source for electric vehicles. © 2014 American Chemical Society.
Journal of Power Sources256p.226 - 2322014年06月-2014年06月
概要：The impedance behaviors of Si-O-C composite film electrodeposited on Cu microcones-arrayed current collector have been investigated to understand the electrochemical process kinetics that influences the cycling performance when used as a highly-durable anode in a lithium battery. The impedance was measured by using impedance spectroscopy in equilibrium conditions at various depths of discharge and during several hundred charge-discharge cycles. The measured impedance was interpreted with an equivalent circuit composed of solid electrolyte interphase (SEI) film, charge transfer and solid state diffusion. The impedance analysis shows that the change of charge transfer resistance is the main contribution to the total resistance change during discharge, but an abrupt augmentation of diffusive resistance at high depth of discharge is also observed which cannot be explained very well by the presented model. The impedance evolution of this electrode during charge-discharge cycles suggests that the slow growth of the SEI film as well as the increase of the electrode density are responsible for the capacity fading after long term cycling. © 2014 Elsevier B.V. All rights reserved.
Electrochimica Acta131p.195 - 2012014年06月-2014年06月
概要：Symmetric cells were prepared with a newly designed separable cell module, which enabled ca. 70 mm by 70 mm electrode sheets to be used for a pouch type 5 Ah class Li-ion battery (LIB). Impedance analysis of the LIB as a full cell state was successfully performed with electrochemical parameters obtained by an impedance analysis of symmetric cells of anodes and cathodes obtained from the operated Li-ion batteries. While the charge transfer resistance of the cathode was found to increase after reassembling the cells symmetrically, other electrochemical parameters were found not to change when comparing the values obtained for full cells with symmetric cells. Eelectrodes degraded by charge/discharge cycling of the battery were also investigated, and the parameter change caused by the degradation was confirmed. © 2014 Elsevier Ltd.
ACS Applied Materials and Interfaces6(19)p.16545 - 165552014年01月-2014年01月
概要：© 2014 American Chemical Society. Nitrogen-doped/undoped thermally reduced graphene oxide (N-rGO) decorated with CoMn2O4 (CMO) nanoparticles were synthesized using a simple one-step hydrothermal method. The activity and stability of this hybrid catalyst were evaluated by preparing air electrodes with both primary and rechargeable zinc-air batteries that consume ambient air. Further, we investigated the relationship between the physical properties and the electrochemical results for hybrid electrodes at various cycles using X-ray diffraction, scanning electron microscopy, galvanodynamic charge-discharging and electrochemical impedance spectroscopy. The structural, morphological and electrocatalytic performances confirm that CMO/N-rGO is a promising material for safe, reliable, and long-lasting air cathodes for both primary and rechargeable zinc-air batteries that consume air under ambient condition.
Journal of the Electrochemical Society161(7)p.D3025 - D30312014年01月-2014年01月
概要：Sn-O-C composites were electrodeposited using organic carbonate solvents and their electrochemical mechanism was thoroughly investigated to achieve desired anode performances, such as high capacity and cycle durability for lithium secondary batteries. Cyclic voltammetry study clarified the multiple stages of electrochemical mechanism during the Sn-O-C composite deposition process. It was revealed that Sn deposition, decomposition of organic electrolytes, and reaction between Li+ and deposited Sn were consecutively carried out. X-ray photoelectron spectroscopy and field emission scanning electron microscopy were performed to characterize how each stage contributes to the formation of the Sn-O-C composite. The results showed increase in metallic Sn composition and dense coating with fine particle sizes with a higher overpotential stage. Afterward, different Sn-O-C composite anodes were prepared by varying charge quantities passing through each deposition stage and their electrochemical performances as anode materials were investigated. Discharge capacities were obtained from the lowest value of 33 mAh g of Sn-1 to the highest value of 429 mAh g of Sn-1 at the 100th cycle by varying deposition conditions. Consequently, it was suggested that anode performance was significantly influenced by an electrodeposition process consisting of three consecutive stages with different overpotential regions and reactions of Li ion with deposited Sn. © 2014 The Electrochemical Society.
RSC Advances4(51)p.26872 - 268802014年01月-2014年01月
概要：Electrodeposition was conducted from an organic carbonate solvent via the potentiostatic technique through three consecutive steps in order to synthesise Sn-O-C composite, which delivered a discharge capacity of 596 mA h g of Sn -1 after 50 cycles. However, the composite anode suffered from a significantly low initial discharge capacity, delivering a discharge capacity of 79 mA h g of Sn -1 until the 5th cycle. It was deduced that the improbably low initial capacity was induced by the deposition of Li-rich compounds, which were formed by electrolyte decomposition accompanied by the reduction product of supporting electrolyte salts during the electrodeposition process, on the surface layer. In order to improve the poor initial capacity, we modified the chemical composition of the surface layer by means of implementing the agitation of the electrolyte during the deposition process. This gave rise to varying the diffusion-layer thickness during the deposition process due to the enhancement of convection by movement of the electrolyte itself. As a result, we achieved improvement of the initial discharge capacity, delivering 572 mA h g of Sn -1 at the 1st cycle and 586 mA h g of Sn -1 at the 50th cycle. It was revealed that the surface layer was composed of a decomposition product of the organic carbonate solvent. Furthermore, a smaller particle size of the Sn-O-C composite was obtained via electrolyte agitation, giving rise to homogeneous shell formation on the Sn compound core. Herein, we thoroughly examined the influence of varying diffusion-layer thickness during the deposition process on the properties of the Sn-O-C composites from an electrochemical standpoint. This journal is © the Partner Organisations 2014.
Journal of Materials Chemistry A2(4)p.883 - 8962014年01月-2014年01月
概要：Silicon is one of the most promising materials for lithium secondary battery anodes. However, silicon anodes have a critical drawback to their practical application, which is capacity degradation due to pulverization of the active material by the large volume change of silicon during charge-discharge cycles. This paper reviews recent studies on silicon-based anodes that have attempted to overcome this poor cycle durability through structural control such as through thin films, porous structures, core-shell structures, and by alloying with other metals, and by application of proper binders. Among them, binder-free Si-O-C composite films prepared by electrodeposition exhibit outstanding cycle durability. The origin of this excellent durability is discussed in depth from the standpoint of chemical and morphological changes. Consequently, the combination of active materials such as Si and Li 2Si2O5 and inactive materials such as Li 2O, Li2CO3, and organic compounds is suggested to result in outstanding properties as a lithium secondary battery anode. © 2014 The Royal Society of Chemistry.
Chemistry Letters43(6)p.901 - 9032014年01月-2014年01月
概要：A carbon-coated Li2S was prepared through an adsorption and successive annealing process by using poly(vinylpyrrolidone) (PVP) and acetylene black (AB) as carbon source with Li2S powder. The coating layer was composed of amorphous carbon and embedded AB particles. The carbon coating was found to effectively alleviate the dissolution of polysulfide and the discharge capacity at the first 15 cycles was 800mAh g-1 with gradual fading afterward. © 2014 The Chemical Society of Japan.
Electrochimica Acta113p.720 - 7292013年12月-2013年12月
概要：A common understanding of polymer electrolyte fuel cells (PEFCs) is important to promote the development of PEFCs. This understanding is crucial because complicated phenomena such as chemical reactions, ion transport, and gas diffusion occur during the operation of PEFCs. Electrochemical impedance spectroscopy (EIS), which can separate reactions into elementary processes, is a powerful tool for the analysis of PEFCs without requiring disassembly of the cell. In this study, the effect of flooding in the cathode catalyst layer of PEFCs was analyzed by EIS using the transmission line model (TLM) to determine the distribution of catalytic reactions in the primary and secondary pores. The analysis was conducted by varying experimental conditions such as the relative humidity of the gases supplied into the anode and cathode, the flow rate, and the partial pressure of oxygen in the gas mixture supplied to the cathode channel. The EIS analysis suggests that the resistance to the catalytic reaction in the primary pores drastically increased with the current density. The results suggest that the flooding preferentially occurred in the primary pores, resulting in the reduction of active sites by generated water. The EIS method is a powerful tool for developing membrane electrode assemblies (MEAs) with effective porosity and tortuosity for gas diffusion and ionic transportation, and furthermore, it is a useful tool for judging the process of MEA preparation. © 2013 Elsevier Ltd. All rights reserved.
Electrochimica Acta110p.403 - 4102013年08月-2013年08月
概要：The structure of the highly durable silicon-based anode prepared by electrodeposition was investigated for volume change and chemical structure. With repeated charge-discharge cycles, the volume change resulting from the anode film thickness decreased, and, after 100 cycles, essentially no difference was observed between the charged and discharged states. The buffering effect of the volume change was considered to be achieved by the formation of Li 2O, Li2CO3, and lithium silicates such as Li4SiO4, whose existence were supported by STEM, EELS, and XPS analyses. From the structural analyses, the main reactions related to the capacity of the silicon-based anode were considered to be the formation of LixSi and Li2Si2O5. LixSi and Li2Si2O5 can be delithiated into Si and SiO2, respectively. © 2013 Elsevier Ltd. All rights reserved.
Journal of Power Sources242p.527 - 5322013年06月-2013年06月
概要：The Sn-O-C composite anode for the Li secondary battery was synthesized by electrodeposition using an organic carbonate solvent. The composite of Sn with organic/inorganic compounds was prepared by the simultaneous reaction of the reduction of Sn2+ ions and electrolysis of the mixture of ethylene carbonate and propylene carbonate. The galvanostatic potential transients for the electrodeposition of the Sn-O-C composite indicate that multiple steps of reactions corresponding to the electrochemical reduction of the tin precursor and the decomposition of organic solvents are involved. The morphology, crystalline structure and chemical composition of the as-deposited Sn-O-C composite anode were characterized to elucidate the mechanism of the synthesis of the buffering matrix enduring volume expansion. The electrochemical behavior of the Sn-O-C composite anode was investigated by cyclic voltammetry and galvanostatical charge/discharged tests. The discharge capacity of 465 mAh (g of Sn)-1 was obtained at the 100th cycle showing 80% of the capacity retention after the 100th cycle. The discharge capacity was stable after the 50th cycle, where the phase transformation of the Sn element from Sn to Li 0.4Sn at the discharged state was found. © 2013 Elsevier B.V. All rights reserved.
Journal of Power Sources222p.503 - 5092013年01月-2013年01月
概要：Electrodeposition methods were developed for the fabrication of Si composite anodes with nickel micronanocones hierarchical structure (MHS) current collectors for Li secondary batteries. This unique structured nickel current collector is electrodeposited in a simple process to create a complex high surface area conductive substrate, as well as to enhance the interfacial strength between active materials and substrate during cyclic lithiation/delithiation. The MHS supported Si composite anode demonstrated outstanding Li+ storage properties with reversible capacity over 800 mAh g-1 (600 μAh cm-2) after 100th cycle with superior retention of 99.6% per cycle. The improved performance of nickel MHS supported Si thick films indicate the potential for their application as electrode materials for high performance energy storage. © 2012 Elsevier B.V. All rights reserved.
Journal of Power Sources222p.442 - 4472013年01月-2013年01月
概要：The impedance of Li-ion battery using a Li4Ti5O12 (LTO) anode for high-power applications was measured at various depths of discharge and temperatures during chargeedischarge cycles. The measured impedance was interpreted with an equivalent circuit made up of anode and cathode, in which the cathode component was composed of two particle size factors. The values obtained for equivalent circuit elements by modeling were in good agreement with the results measured by other techniques, and indicated that the capacity fade of this Li-ion battery due to cycling is mainly caused by the increase of interfacial resistance and a decrease in the capacity of the LiCoO2 cathode. These results suggest that the cyclability of this LIB was improved by using an LTO anode, and show the validity of the equivalent circuit for interpreting the causes of capacity fade. © 2012 Elsevier B.V. All rights reserved.
Nara, Hiroki; Yokoshima, Tokihiko; Otaki, Mitsutoshi; Momma, Toshiyuki; Osaka, Tetsuya
Electrochimica Acta110p.403 - 4102013年01月-2013年01月
CHEMISTRY LETTERS42(3)p.318 - 3202013年-2013年
Journal of Power Sources216p.304 - 3072012年10月-2012年10月
概要：Ac impedance spectra of electrochemical systems are analyzed by considering adequate equivalent circuits, while the differentiation of responses for each elemental step is sometimes difficult. In this study, enlarged impedances were measured by lowering the temperature of a lithium ion battery (LIB) to make the separation of confusing responses easier. The impedance spectra obtained at the temperatures between -20 °C and 20 °C showed drastic change in sizes with shifting of the characteristic frequency. The analysis of impedance spectra using an equivalent circuit revealed changes in resistance of each component and shifting of the time constant for each elemental step. The frequency domain of impedance response of solid electrolyte interphase (SEI) was found to overlap with that of the inductive component of the outer electric lead at 20 °C in our study. The impedance measurement at the low temperatures is considered to be useful for the detection of the SEI and the accurate evaluation of LIB. © 2012 Elsevier B.V.
Journal of Power Sources205p.483 - 4862012年05月-2012年05月
概要：To analyze impedance response of an electrochemical system, it is important to model the system with an adequate equivalent circuit. In the present work, an equivalent circuit was designed for the analysis of lithium ion batteries with the contributions of a variety of diffusion parameters resulting from the various particle sizes for the cathode and the solid-electrolyte interphase formed on the anode particles, as well as electrochemical reactions and inductive components. Residual errors resulting from the data fitting was investigated for a variety of equivalent circuits used. The electrochemical impedance of the electrodes in commercial lithium ion batteries at various states of charge was analyzed to evaluate the proposed circuit. © 2012 Elsevier B.V. All rights reserved.
Chemistry Letters41(4)p.444 - 4462012年04月-2012年04月
概要：The degradation of the commercial Li ion battery was analyzed by electrochemical impedance spectroscopy, where our previous proposed equivalent circuit was applied. The degradation with the cycling was clearly explained by the main parameters of capacitive and resistive components, i.e., it responded until 300 cycles to the decrease in capacitive component, while after 300 to 550 cycles to the increase in resistive component. © 2012 The Chemical Society of Japan.
Energy and Environmental Science5(4)p.6500 - 65052012年01月-2012年01月
概要：A highly durable SiOC composite anode was prepared for use in lithium secondary batteries. The SiOC composite was synthesized by electrodeposition of SiCl
ELECTROCHIMICA ACTA82p.1 - 22012年-2012年
表面技術 = The journal of the Surface Finishing Society of Japan62(12)p.720 - 7222011年12月-2011年12月
Electrochemistry Communications13(9)p.969 - 9722011年09月-2011年09月
概要：A novel SiOC composite anode material for a Li battery was realized by electrochemical co-deposition of Si, C, and O elements. The composite was deposited by reduction of SiCl4 in a propylene carbonate based solution. After the initiation process by reduction of the composite in a Li+ containing electrolyte solution, the SiOC composite was found to be about 3.3 μm in average thickness and the composite performed as a Li battery anode with over 1000 mAh g- 1 of Si for more than 2000 cycles, and moreover have continued for 7000 cycles with gradual degradation. © 2011 Elsevier B.V. All rights reserved.
Journal of the Electrochemical Society158(9)p.B1184 - B11912011年08月-2011年08月
概要：A novel transmission line (TML) model is proposed for the impedance analysis, which is nondestructive measurement, on degraded cathode catalyst layers in polymer electrolyte fuel cells (PEFCs). The test PEFC consisted of 1.0 mg/cm2 of Pt-Ru as an anode catalyst, 1.0 mg/cm2 of Pt as a cathode catalyst, and Nafion 212 as an electrolyte. The model counts the distribution of the oxygen reduction reaction (ORR) at the inside and outside of agglomerates of the carbon supported catalysts. We demonstrated the importance of the distribution of the ORR for achieving excellent agreement between the calculated and experimental data. The change in parameters obtained by impedance analysis with the TML model was verified by destructive tests, such as transmission electron microscopy, field emission scanning electron microscopy, cyclic voltammetry, micro-Fourier transform infrared spectroscopy and nitrogen adsorption-desorption measurements. Variations of the parameters such as the charge transfer resistance, the double layer capacitance, and the ionic resistance inside and outside the agglomerates of the carbon supported catalysts could be explained by multiple considerations of these destructive test results. Impedance analysis with the TML model offers the possibility understanding the state of degraded cathode catalyst layers in membrane electrode assemblies without the need for disassembling PEFCs. © 2011 The Electrochemical Society.
Journal of Power Sources196(15)p.6483 - 64872011年08月-2011年08月
概要：Many efforts have been paid to realize the superior anodes for future Li batteries in either the dry Ar atmosphere or the dry air atmosphere. In this work, in order to clarify the effects of such atmospheres, the most reactive anodes of Li were freshly electrodeposited under the dry Ar or under the dry air condition. The Solid Electrolyte Interface (SEI) formed during the electrodeposition of Li anodes is revealed to have a different chemical composition and protective feature. The Li deposited under the dry air was revealed to have longer cycle life in the electrolyte than that deposited in Ar, even in the electrolyte containing ionic liquid. From the XPS results, the SEI formed in dry air is proved to be different from that formed in Ar gas atmospheres, that is, the SEI formed in dry air consists of Li 2CO3 and Li nitride. In order to improve the performance of the anodes, the atmosphere for the initial preparation of the anode/electrolyte interface should be tuned. © 2011 Elsevier B.V. All rights reserved.
Modern Electroplating: Fifth Editionp.421 - 4322011年02月-2011年02月
Journal of Power Sources195(13)p.4065 - 40712010年07月-2010年07月
概要：Sulfated zirconia is an inorganic solid superacid having sulfate groups covalently bonded to its surface. In this work, sulfated zirconia is synthesized by a solvent-free method to obtain it in the nanoparticle form. This nanostructured sulfated zirconia has been evaluated in terms of (i) chemical stability to hydrolysis and to hydrogen peroxide by thermogravimetric analysis, and (ii) influences on Pt catalyst activity by cyclic voltammetry using sulfated-zirconia dispersion as a supporting electrolyte solution. The results demonstrate that our sulfated zirconia is stable almost perfectly to hydrolysis but partly decomposed by a Fenton reagent containing hydrogen peroxide and Fe2+. In addition, we show that oxygen reduction activity of Pt catalyst in a sulfated-zirconia dispersion is comparatively high (specific activity at 0.9 V vs. RHE, i0.9: ca. 17 μA cm-2) compared to that in a 0.5 M sulfuric acid solution (i0.9: ca. 15 μA cm-2). Finally, we demonstrate that sulfated zirconia does not influence hydrogen oxidation reaction. These results lead us to conclude that sulfated zirconia is a promising proton conductor for fuel cells. © 2010.
Tominaka, Satoshi;Goto, Kazuya;Momma, Toshiyuki;Osaka, Tetsuya
Journal of Power Sources192(2)p.316 - 3232009年07月-2009年07月
概要：Catalyst layers of direct methanol fuel cells (DMFCs) are modified by in situ electropolymerization of m-aminobenzenesulfonic acid. By using electrochemical impedance spectroscopy and porosimetry, this modification is found to add polymer electrolyte into primary pores (<10 nm), where ionic resistance is high for lack of polymer electrolyte (i.e., Nafion), and the additional electrolyte successfully decreases the ionic resistance by 10-15% compared to the plain carbon surface with a slight ion-conductivity (>40 kΩ cm). In view of methanol oxidation characteristics, this modification decreases the resistance by ca. 25% (from 5.1 Ω cm2 to 3.7 Ω cm2) at 0.6 V vs. DHE, resulting in the increase in the cell voltage of DMFC test by ca. 20 mV. The clear relation between the performance and the microstructures is concluded to be helpful to understand the performance of fuel cell electrodes in detail. © 2009 Elsevier B.V. All rights reserved.
Momma, Toshiyuki; Park, Jong Eun; Park, Jong Eun; Kim, Jandee; Yamazaki, Yohtaro; Osaka, Tetsuya
Electrochemistry77(6)p.465 - 4672009年06月-2009年06月
概要：Non-platinum nanoparticles (Pd, Au, PdAu) have been prepared by sonochemical synthesis. The nanoparticle-modified electrodes showed improved catalytic activity for oxygen reduction compared with Pt nanoparticles in alkaline solution even in the presence of methanol.
Tribology International42(6)p.779 - 7912009年06月-2009年06月
概要：As potential high capacity anode materials for lithium ion batteries, the Sn and Ni-Sn alloy coatings have been investigated by many electrochemical researchers. However, their mechanical properties have not been extensively studied, despite the fact that such anode films may fail mechanically during service. Thus, in this study nanoindentation and nanowear tests have been performed. Nanoindentation tests reveal that the ability to carry the load dramatically reduces in the Sn coating after one charge-discharge cycle which makes the plastic strain accumulation in the copper substrate play a greater contribution to crack formation and propagation in repeated charge-discharge cycling. Upon the nanoindentation analysis, it also shows that the pores formed by lithiation/delithiation can easily collapse at low loads. Furthermore, nanowear tests explore that the damage resistance of the Sn-Ni alloy film significantly improves after one charge-discharge cycle but it decreases in the Sn film after the same charge-discharge cycle; this explains why the degradation rate of the Ni-Sn alloy is slow after the first charge-discharge cycle and why the high capacity is maintained in further cycling. The links between the mechanical characterization and the degradation in charge-discharge cycling are also discussed. © 2008 Elsevier Ltd. All rights reserved.
Kim, Jandee;Park, Jong-Eun;Momma, Toshiyuki;Osaka, Tetsuya
Electrochimica Acta54(12)p.3412 - 34182009年04月-2009年04月
概要：Nanoparticles of Pd-Sn were prepared under various conditions by applying ultrasonic irradiation, and their electrocatalytic activity for oxygen reduction was evaluated in 0.5 M KOH. The average size of Pd-Sn nanoparticles thus prepared was about 3-5 nm. The Pd in Pd-Sn nanoparticles was found to be mostly in the metallic state. The electrocatalytic activity of the Pd-Sn nanoparticles for the oxygen reduction reaction (ORR) is greater than Pt or Pd nanoparticles in alkaline media. The molar ratio of Pd to Sn metal ions in the synthesizing solution, their initial concentrations, the concentration of ethanol, which increases primary hydrogen radicals during sonolysis, and the concentration of citric acid were found to affect the size distribution of the Pd-Sn nanoparticles, and therefore, those factors controlled the electrocatalytic activity for ORR. Particularly, the concentration of citric acid was found to be important for controlling the surface property on Pd-Sn particles to adjust the electrocatalytic activity for ORR. © 2009 Elsevier Ltd. All rights reserved.
Kim, Jandee;Momma, Toshiyuki;Osaka, Tetsuya
Journal of Power Sources189(2)p.909 - 9152009年04月-2009年04月
概要：Carbon-supported Pd-Sn (Pd-Sn/C) catalyst was prepared under ultrasonic irradiation, and its electrocatalytic activity for oxygen reduction reaction (ORR) was evaluated in 0.5 M KOH. TEM images showed that the prepared Pd-Sn/C catalyst particles are smaller in average size than carbon-supported Pd (Pd/C) catalyst particles. XRD and XPS results indicated the small particle size and the electronic interaction between Pd and Sn for the Pd-Sn/C catalyst. The Pd-Sn/C catalyst has a higher ORR activity than the Pd/C catalyst in alkaline media. In addition, the Pd-Sn/C catalyst showed a lower Tafel slope and a larger number of electrons transferred for ORR, compared with those of the Pd/C catalyst. These results indicate that Sn influences both the kinetics and the mechanism of ORR. Based on these results, the Pd-Sn/C catalyst prepared by using ultrasonic irradiation can be expected as a promising ORR catalyst in alkaline media. © 2009 Elsevier B.V. All rights reserved.
Kim, Jandee;Momma, Toshiyuki;Osaka, Tetsuya
Journal of Power Sources189(2)p.999 - 10022009年04月-2009年04月
概要：Direct methanol alkaline fuel cell (DMAFC) using anion exchange membrane (AEM) was operated in passive condition. Cell with AEM exhibits a higher open circuit voltage (OCV) and superior cell performance than those in cell using Nafion. From the concentration dependences of methanol, KOH in fuel and ionomer in anode catalyst layer, it is found that the key factors are to improve the ionic conductivity at the anode and to form a favorable ion conductive path in catalyst layer in order to enhance the cell performance. In addition, by using home-made Pd-Sn/C catalyst as a cathode catalyst on DMAFC, the membrane electrode assembly (MEA) using Pd-Sn/C catalyst as cathode exhibits the higher performance than the usual commercially available Pt/C catalyst in high methanol concentration. Therefore, the Pd-Sn/C catalyst with high tolerance for methanol is expected as the promising oxygen reduction reaction (ORR) catalyst in DMAFC. © 2009 Elsevier B.V. All rights reserved.
Journal of Power Sources185(2)p.656 - 6632008年12月-2008年12月
概要：Sulfated zirconia nanoparticles are evaluated as a possible alternative for a solid proton conductor in a fuel-cell catalyst layer. Two methods are applied for the synthesis of the nanoparticles, i.e.: (i) a conventional method treating ZrO2 particles in sulfuric acid, and (ii) a solvent-free method directly synthesizing sulfated zirconia nanoparticles through the thermal decomposition of a mixture of ZrOCl2 and (NH4)2SO4. The nanoparticles synthesized by the solvent-free method have a size of 5-10 nm and an amorphous structure, and moreover their properties are promising in view of the application. In particular, the proton conductivity of the nanoparticles is high enough, i.e. of the 10-2 S cm-1 order, to be comparable to that of Nafion. Even though they possibly reduce the activity of Pt catalyst, layers containing sulfated zirconia as a proton conductor prove to be active as catalyst in fuel cell prototypes. Compared with conventional, Nafion-based cells, the maximum power density of the cells using sulfated zirconia is about one third. We believe that improvement in the preparation procedures for catalyst layers and membrane electrode assemblies will improve the cell performance. Therefore sulfated zirconia can be a valid proton conductor for fuel cell application. © 2008 Elsevier B.V. All rights reserved.
Journal of the American Chemical Society130(32)p.10456 - 104572008年08月-2008年08月
概要：This paper proposes a novel design for a microfuel cell as an on-chip power source and demonstrates its fabrication and operation to prove the concept. Its simple design is important from the viewpoints of fabrication (e.g., replication), integration, and compatibility with other microdevices. In testing, the prototype cell was able to generate electric power (maximum: ca. 1.4 μW) on methanol without pumps under both neutral and acidic conditions. As for the size, the electrode part of the cell (two cathodes and one anode) is 400 μm in width and 6 mm in length. The evaluation demonstrated that the proposed design is a promising on-chip power source for miniature devices. Copyright © 2008 American Chemical Society.
Journal of Materials Chemistry18(30)p.3581 - 35872008年07月-2008年07月
概要：Polyether chains have been successfully grafted onto the interlayer surface of a Dion-Jacobson-type layered perovskite, HLaNb2O 7·xH2O, by a reaction between an n-decoxy-derivative of HLaNb2O7·xH2O and CH3(OCH2CH2)mOH (1 ≤ m ≤ 4). After the reaction, the interlayer distance decreases from 2.73 nm to 1.58 (m = 1), 2.07 (m = 2), 2.28 (m = 3), and 2.69 (m = 4) nm. Solid-state 13C CP/MAS NMR spectroscopy indicates that the CH3(OCH2CH 2)mO- groups are bound to the interlayer surface of HLaNb2O7·xH2O. The n-decoxy groups are completely removed by the reaction with CH3(OCH2CH 2)mOH (m = 2 and 3), while a part of the n-decoxy groups remain after the reaction with CH3(OCH2CH 2)mOH (m = 1 and 4). Upon treatment of the CH 3(OCH2CH2)mO-grafted HLaNb 2O7·xH2O (m = 2 or 3) with a CH 3(OCH2CH2)mOH solution of LiClO 4, the interlayer distance decreases further to 1.78 (m = 2) and 2.01 (m = 3) nm. Inductively coupled plasma emission spectrometry reveals the presence of lithium (0.22 (m = 2) and 0.24 (m = 3) per [LaNb2O 7]). The presence of ClO4 - ions is demonstrated by Raman spectroscopy, and the position of the ν1(A1) band indicates the presence of isolated ClO4 - ions in the interlayer space. After treatment with a LiClO4 solution, CH 3(OCH2CH2)mO-grafted HLaNb 2O7·xH2O (m = 2 and 3) exhibits ionic conductivity, and no clear temperature dependence is observed. © 2008 The Royal Society of Chemistry.
Chemical Communications(25)p.2888 - 28902008年06月-2008年06月
概要：A perpendicular mesoporous platinum electrode with a flat surface is successfully synthesized by electrodeposition using titania nanopillars as template, and the electrochemical studies indicate that this material is a promising catalytic electrode for fuel cells because of its high surface area and perpendicular nanopores. © The Royal Society of Chemistry.
Tominaka, Satoshi;Momma, Toshiyuki;Osaka, Tetsuya
Electrochimica Acta53(14)p.4679 - 46862008年05月-2008年05月
概要：Pd-Co alloy has been recently proposed as a catalyst for the cathode of direct methanol fuel cells with both excellent oxygen reduction activity and methanol tolerance, hence electrodeposition of this alloy is an attractive approach for synthesizing porous metal electrodes with high methanol tolerance in direct methanol fuel cells. In this study, we electrodeposited two types of Pd-Co films onto Au substrates by applying different current density (-10 or -200 mA cm-2); and then characterized them in terms of morphology, composition, crystal structure, and catalytic activity. Pd-Co deposited at -10 mA cm-2 was smooth and possessed smaller particles (ca. 10 nm), while that at -200 mA cm-2 was dendritic (or rough) and possessed larger particles (ca. 50 nm). Both the Pd-Co alloys were found to be almost the same structure, i.e. a solid solution of ca. Pd7Co3 with Pd-skin, and also confirmed to possess comparable activity in oxygen reduction to Pt (potential difference at 1.0 μA cm-2 was 0.05 V). As for methanol tolerance, cell-voltage was not influenced by addition of 1 mol dm-3 methanol to the oxidant solution. Our approach provides fundamental technique for synthesizing Pd-Co porous metal electrodes by electrodeposition. © 2008 Elsevier Ltd. All rights reserved.
Momma, Toshiyuki; Momma, Toshiyuki; Nara, Hiroki; Osaka, Tetsuya
Electrochemistry76(4)p.270 - 2752008年04月-2008年04月
概要：A simple numerical simulation of current flowing through electronic devices was examined for a hybrid power supply system composed of a DMFC and a capacitor connected in parallel. The simulation was investigated by representing a combination of ohmic resistance, charge transfer reaction resistance, mass transfer resistance and double layer capacitance of a DMFC as a simple ideal resistor, based on measured data when DMFC was generating electricity. The simulation result was found to agree with experimental measured current flowing through the DMFC and the capacitor, although a slight disagreement was observed because of the presence of ohmic resistance between circuit components. The simulation of DMFC-capacitor hybrid power supply system indicated the importance of the inner resistance of the capacitor. The hybrid simulation was also applied to a system assumed to consist of μDMFC and micro electrochemical capacitor (MECC) system. The effect of applying a DC-DC converter to the system was indicated. The simulation allows to predict the degree of improvement required without performing actual fabrication of μDMFC and MECC.
Nara, Hiroki; Momma, Toshiyuki; Osaka, Tetsuya
Electrochemistry76(4)p.276 - 2812008年04月-2008年04月
概要：The feasibility of a di-block copolymer, composed of a polyethylene oxide (PEO) chain and a polystyrene (PS) chain covalently bonded, as the gel electrolyte for lithium secondary batteries was investigated. The PEO-PS di-block copolymer gel electrolyte showed a high ionic conductivity of∼ 1 mS/cm at room temperature. Moreover, it retained good mechanical strength within a co-continuous phase separated structure, and it suppressed the dendritic deposition of Li. Indications were that the interface between the electrolyte and the Li metal was chemically stable, as a result of the PEO phase fixed to PS by covalent bonding. In addition, it was indicated that the Li/PEO-PS di-block copolymer gel electrolyte/LiFeP04 cell had a high charge-discharge efficiency of∼99% during 30 cycles, while maintaining a discharge capacity of 124 mAh/g.
Chemistry Letters37(2)p.142 - 1432008年02月-2008年02月
概要：A mesoporous Sn anode was electrodeposited in the presence of lyotropic liquid crystals made of nonionic surfactants. The introduction of mesoporous structure was effective for the accommodation of volume change of Sn during charge and discharge cycling of Li ions. The discharge capacity of the mesoporous Sn anode at 1 C rate was as high as 425mA h g-1 at the 100th cycle, and that was as high as 320mA h g-1 at the 100th cycle even though at 5 C rate. Copyright © 2008 The Chemical Society of Japan.
Journal of Physics D: Applied Physics41(2)2008年01月-2008年01月
概要：In lithium ion batteries, it has previously been shown that Ni-Sn thin film anodes containing 62 at.% Sn show outstanding electrochemical characteristics, e.g. good capacity and endurance, during charge-discharge cycling. However, their mechanical response, which is likely related to their lifetime in service, has so far received relatively little attention. To address this, nanoindentation and nanowear techniques have been used to characterize the mechanical properties of thin Ni-Sn films electrodeposited on a copper substrate. In situ morphology analysis together with in situ stress measurement has been performed to assess the properties of Ni-Sn thin film anodes during electrochemical cycling. The change in mechanical properties, residual stress and fracture behaviour of the anodes is related to the phase changes which occur during charge-discharge cycling. The correlation between the mechanical properties of the films and their charge-discharge characteristics serves as a useful indicator for optimized design of a Sn-based intermetallic anode film for lithium ion secondary batteries. © 2008 IOP Publishing Ltd.
Tominaka, Satoshi;Akiyama, Naohisa;Croce, Fausto;Momma, Toshiyuki;Scrosati, Bruno;Osaka, Tetsuya
JOURNAL OF POWER SOURCES185(2)p.656 - 6632008年-2008年
Tominaka Satoshi;Wu Chia-Wen;Momma Toshiyuki;Kuroda Kazuyuki;Osaka Tetsuya
Chemical communications (Cambridge, England)(25)2008年-2008年
概要：:A perpendicular mesoporous platinum electrode with a flat surface is successfully synthesized by electrodeposition using titania nanopillars as template, and the electrochemical studies indicate that this material is a promising catalytic electrode for fuel cells because of its high surface area and perpendicular nanopores.
Tominaka Satoshi;Ohta Sousuke;Obata Hiroyuki;Momma Toshiyuki;Osaka Tetsuya
Journal of the American Chemical Society130(32)2008年-2008年
概要：:This paper proposes a novel design for a microfuel cell as an on-chip power source and demonstrates its fabrication and operation to prove the concept. Its simple design is important from the viewpoints of fabrication (e.g., replication), integration, and compatibility with other microdevices. In testing, the prototype cell was able to generate electric power (maximum: ca. 1.4 microW) on methanol without pumps under both neutral and acidic conditions. As for the size, the electrode part of the cell (two cathodes and one anode) is 400 microns in width and 6 mm in length. The evaluation demonstrated that the proposed design is a promising on-chip power source for miniature devices.
Electrochimica Acta53(2)p.604 - 6092007年12月-2007年12月
概要：Nanostructured Pt particles are directly deposited onto a Ni foam by utilizing displacement plating after a lyotropic liquid crystalline phase including Pt species was prepared within macropores of the Ni foam. The EDS mapping of Pt after deposition corresponds to the macroscopic framework of the Ni foam, indicating the uniform displacement plating of Pt on the surface of the Ni foam. The Pt particles of 150-250 nm in size are formed over the entire area of the surface of the Ni foam. The TEM images prove that the nanoscale rods (width: about 3 nm) are aggregated with each other to form nanoscale porosity. The active area of Pt can be estimated to be ca. 12 m2/g by using the cyclic voltammogram in sulfuric acid. Our method realizes one-step production of hierarchical macro-meso type porous electrodes. © 2007 Elsevier Ltd. All rights reserved.
ECS Transactions11(1 PART 2)p.1369 - 13772007年12月-2007年12月
概要：Pd-Co was electrodeposited as a rough cathode catalyst for a direct methanol fuel cell fabricated using micro-electromechanical systems technology. Pd-Co was electrodeposited at -10 mA/cm2 for 60 s or -200 mA/cm 2 for 5 s. The deposits were evaluated with respect to microstructures, electrochemical characteristics, and fuel cell performances. As a result, oxygen reduction activity of the sample prepared at -200 mA/cm 2 was higher than that prepared at 10 mA/cm , while the electrochemically active surface areas were almost the same. Microstructures of the former and the latter were observed dendritic and flat, respectively. We conclude that the difference of oxygen reduction activity is attributed to the difference of the microstructure. In addition, we modified the dendritic sample by depositing Pd-Co at -0.75 V vs. Ag/AgCl. The modification increased open circuit potential for oxygen reduction by 30 mV from 0.70 to 0.73 V. ©The Electrochemical Society.
Tominaka, Satoshi;Akiyama, Naohisa;Momma, Toshiyuki;Osaka, Tetsuya
Journal of the Electrochemical Society154(9)p.B902 - B9092007年08月-2007年08月
概要：An impedance analysis method for the catalyst layers of a direct methanol fuel cell is evaluated through demonstrating analyses and comparison of two types of the catalyst layers. The catalyst layers were prepared with different dispersing solvents: ethyleneglycol dimethyl ether or isopropyl alcohol aqueous solution. Methanol oxidation current of the catalyst layer prepared with the former solvent was more than twice that with the latter. The proposed method was revealed to have the potential for analyzing the difference clearly in terms of parameters, using our transmission-line equivalent circuit for the catalyst layers based on the assumption of primary and secondary pores. The parameters indicate that the main drawback of the catalyst layer prepared with the latter solvent is 85 times larger ionic resistance in the secondary pores. Moreover, precise analyses on the parameters indicate the microstructures of the catalyst layers, which correspond to a model reported previously. We conclude that this method is effective in analyzing the catalyst layer of the fuel cell. © 2007 The Electrochemical Society.
Park, Jong-Eun;Momma, Toshiyuki;Osaka, Tetsuya
Electrochimica Acta52(19)p.5914 - 59232007年05月-2007年05月
概要：Different shapes (nanosphere or nanorod) of gold nanoparticles (Au-NPs) were synthesized with and without ultrasonic irradiation in the presence of citric acid. Spherical-shaped and rod-shaped Au-NPs showed different surface plasmon resonance (SPR) absorption bands. The Au-NPs with different shapes were immobilized on a monolayer of 3-aminopropyltriethoxysilane (APS) coated on an indium-tin oxide (ITO) electrode. The potential dependence of the SPR band of different shaped Au-NPs in an aqueous solution was explored. The SPR band and intensity changes of the Au-NPs were found to depend on the applied potential. The spherical-shaped and rod-shaped Au-NPs showed different SPR absorption behaviors when potential was applied. These behavior changes were interpreted as the result of the potential-induced changes of the local dielectric environment around the nanoparticles due to molecular absorption/desorption and the charging/discharging of the particles. © 2007 Elsevier Ltd. All rights reserved.
Mukaibo, H.;Momma, T.;Shacham-Diamand, Y.;Osaka, T.;Kodaira, M.
Electrochemical and Solid-State Letters10(3)p.A70 - A732007年02月-2007年02月
概要：The stress of the electrodeposited pure Sn and the Ni-62 atom % Sn alloy thin film electrodes during cycling was measured in situ using an optical cantilever method. The results revealed that the Ni-62 atom % Sn alloy electrode with better cycle endurance actually experiences larger stress compared to the pure Sn electrode. Furthermore, the stress-release phenomenon during the open-circuit period has been confirmed for the first time. This paper demonstrates that the cantilever bending method is effective for the in situ study of the stress development, transition, and hence the phenomena taking place within the Sn-based electrodes. © 2007 The Electrochemical Society.
Yamauchi, Yusuke;Komatsu, Masaki;Takai, Azusa;Sebata, Ryusuke;Sawada, Makoto;Momma, Toshiyuki;Fuziwara, Minekazu;Osaka, Tetsuya;Kuroda, Kazuyuki
ELECTROCHIMICA ACTA53(2)p.604 - 6092007年-2007年
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers45(10 A)p.7944 - 79482006年10月-2006年10月
概要：High-efficientcy micro-electrochemical devices are realized by increasing electrode surface areas while maintaining keeping chip size. The use of three dimensional (3-D) electrodes instead of planar electrodes is effective for this purpose. To realize a metal pattern on 3-D structures, spray coating was utilized and the optimum condition for achieving a good photoresist step coverage was determined. A good step coverage of the photoresist was obtained on the obtuse corner formed by the anisotropic wet etching of (100) silicon and even on the vertical corner formed by deep reactive ion etching (RIE). We applied this method to fabricate a high-performance micro direct methanol fuel cell (μDMFC). An open circuit voltage of 548 mV and a maximum power density of 0.72 mW/cm2 were obtained at room temperature with 2 M methanol. © 2006 The Japan Society of Applied Physics.
Science and Technology of Advanced Materials7(5)p.395 - 3962006年07月-2006年07月
Science and Technology of Advanced Materials7(5)p.438 - 4452006年07月-2006年07月
概要：We have developed an excellent process for selective deposition of mesoporous Pt through tailored microfabrication steps via the "Solvent-Evaporation-mediated Direct Physical Casting (SEDPC)" method. The direct observation by high-resolution scanning microscopy (HR-SEM) shows the formation of an ordered mesoporous structure in a very confined area. The cyclic voltammogram of the mesoporous Pt reveals a typical feature of Pt surface. The surface morphology and ordering of the mesostructure strongly depend on the electrodeposition conditions (constant-current and constant-potential depositions). The roughness factors are greatly enhanced as the charge densities in the constant-current deposition are increased. These findings are important for the morphological design of mesoporous metals in a micrometer scale. © 2006 NIMS and Elsevier Ltd.
Journal of Materials Chemistry16(23)p.2229 - 22342006年06月-2006年06月
概要：Mesoporous intermetallic Pt-Ni alloys with various compositions have been produced by the chemical reduction of two metal (nickel and platinum) salts dissolved in aqueous domains of a lyotropic liquid crystalline (LLC) phase. The mesoporous Pt-Ni alloys are small particles less than 100 nm in size and exhibit high specific surface areas higher than 40 m2 g -1. The ordering of the mesostructure decreases with increasing Ni content in the alloys. The high resolution scanning electron microscopic (HR-SEM) images show that the porous nanostructures are indeed formed over the entire area on the external surface of the particles. The lattice parameters of the alloys decrease with the increasing Ni content, implying the incorporation of Ni. The X-ray photoelectron spectroscopic (XPS) data show that Ni atoms in the alloys are thought to be in the zerovalent metallic state (Ni0). The transmission electron microscopic (TEM) images prove that the lattice fringes assigned to a fcc structure are randomly oriented in the pore walls. The energy-dispersive X-ray spectroscopic (EDS) mapping shows uniform distribution of Ni atoms in the porous matrix. These results indicate the formation of mesoporous intermetallic Pt-Ni alloys. © The Royal Society of Chemistry 2006.
Shimizu, Takahiro; Shimizu, Takahiro; Mohamedi, Mohamed; Momma, Toshiyuki; Momma, Toshiyuki; Osaka, Tetsuya; Osaka, Tetsuya
Electrochemistry74(4)p.326 - 3312006年04月-2006年04月
概要：This paper describes characteristics of passive direct methanol fuel cell (DMFC), especially the effect of the thickness of electrolyte membrane. Cell performances were compared for membrane electrode assemblies (MEAs) made with Nafion 112, 115, and 117, whose typical thicknesses were 51 μm, 127 mu;m, and 183 mu;m, respectively. The MEA made with Nafion 112 showed performance inferior to the other MEAs with thicker membranes. It appears that the mass of methanol permeated to the cathode through Nafion 112 was large, resulting in the loss of a large quantity of fuel, because its thickness was the smallest among the membranes used in this experiment. The observation of fuel level in the reservoir during open circuit stand indicated that most of the fuel was lost by methanol crossover and evaporation due to the rise in cell temperature. Also, the relationship between the concentration of methanol and the electrode potential at open circuit was investigated with a pseudo dynamic hydrogen electrode calibrated against an Ag/AgCl reference electrode. We found that it is essential to overcome the loss of fuel by methanol crossover and evaporation, which decreases the performance of the anode significantly even when the cell is in the stand-by mode.
Chemistry Letters35(1)p.10 - 112006年01月-2006年01月
概要：On the evaluation of catalyst layers in direct methanol fuel cell (DMFC), we applied the proposed electrochemical cell which enabled to evaluate the catalyst layers without an electrolyte solution circumstance. In addition, properties of polymer electrolytes, such as ionic conductivities inside or outside agglomerates of catalysts were evaluated separately by electrochemical impedance spectroscopy with an analysis using the proposed equivalent circuit. This method also suggested its possibility for evaluating a distribution of the electrolytes in catalyst layers. Copyright © 2006 The Chemical Society of Japan.
Chemistry of Materials17(25)p.6342 - 63482005年12月-2005年12月
概要：Two-dimensional hexagonally ordered mesoporous Pt particles are prepared by Pt deposition in the aqueous domains of lyotropic liquid crystals (LLC) by chemical reduction with Zn powders. Interestingly, the framework is composed of connected nanoparticles of about 3 nm in size. Moreover, it is proved that the lattice fringes on the atomic crystallinity are coherently extended across the several nanoparticles in the framework. Such a framework composed of connected nanoparticles with extended crystallinity is uniquely created by using LLC as a soft template, which is not attainable by a traditional approach using mesoporous silica as a hard template. Through the structural identification, the formation mechanism of mesoporous Pt in the presence of LLC is thought to be continuous deposition of Pt nanoparticles from one nanoparticle. © 2005 American Chemical Society.
Digest of Technical Papers - International Conference on Solid State Sensors and Actuators and Microsystems, TRANSDUCERS '052p.1437 - 14402005年11月-2005年11月
概要：High efficient micro electrochemical devices are realized by the increase of the electrode surface areas keeping the chip size. Use of the 3-D electrodes instead of the planar electrodes is quite effective for this purpose. To realize a metal pattern on 3-D structures, spray coating method was utilized and the optimum condition to achieve good step coverage was observed. Good step coverage of photoresist was obtained on the obtuse corner formed by anisotropic wet etching of (100) silicon and even vertical comer formed by deep RIE. We applied this method to fabricate a high performance micro direct methanol fuel cell (μDMFC). The open circuit voltage of 548mV and the maximum power density of 0.72mW/cm2 were obtained at room temperature with 2M methanol. ©2005 IEEE.
Mukaibo, H;Momma, T;Osaka, T
Journal of Power Sources146(1-2)p.457 - 4632005年08月-2005年08月
概要：We have reported in our past work that electrodeposited Sn-Ni alloy with different composition show considerably different performance as anode materials for Li-ion batteries, and the performance was remarkably well (ca. 650 mAh g-1 at 70th cycle) when the composition was controlled to Sn 62Ni38. In this work, structural changes during charge discharge cycling of Sn-Ni alloy with different composition were investigated to evaluate their differences in the cycle performance. From the XRD result, Ni3Sn4 phase was the main phase seen in Sn 62Ni38, and its reversible reactivity with Li was confirmed. We suggest that this is the key phase for its high capacity and lengthened cycle life. From Sn54Ni46, which showed low capacity, only a metastable phase close to the structure of SnNi was confirmed. The results from Sn84Ni16 indicated the presence of pure Sn and Sn rich metastable phase would lead to relatively fast electrode degradation. © 2005 Elsevier B.V. All rights reserved.
Yamauchi, Y.; Yamauchi, Y.; Nair, S. Sadasivan; Nair, S. Sadasivan; Yokoshima, T.; Momma, T.; Momma, T.; Osaka, T.; Osaka, T.; Osaka, T.; Kuroda, K.; Kuroda, K.; Kuroda, K.; Kuroda, K.
Studies in Surface Science and Catalysis156p.457 - 4642005年07月-2005年07月
概要：This article summarizes our recent studies on the synthesis of highly ordered mesostructured Ni and Ni-Co alloys by electroless deposition method. We propose that a careful control over the nucleation as well as the grain growth by reducing agents can lead to the formation of a highly ordered mesostructure from a lyotropic liquid crystalline phase (LLC). The sophisticated combination of dimethylamineborane (DMAB) and sodium borohydride (SBH) in an electroless plating bath produces highly ordered mesoporous Ni, and this technique can be extended to prepare a series of mesostructured Ni-Co alloys with various compositions. The composition of the alloys can be varied easily by controlling the metal compositions in the plating bath. © 2005 Elsevier B.V. All rights reserved.
Journal of Materials Chemistry15(20)p.1987 - 19942005年05月-2005年05月
概要：Mesostructured Ni and Co particles are formed by metal deposition in the aqueous domains of lyotropic liquid crystals (LLC) using different reducing agents. We have investigated the role of reducing agents in metal deposition for the synthesis of highly-ordered mesoporous metals by electroless deposition. Slow metal deposition accompanied by the autocatalytic reaction of dimethylamineborane (DMAS), caused by the combination of Ni and DMAB, led to the formation of highly-ordered mesostructured Ni. © The Royal Society of Chemistry 2005.
Motokawa, S;Mohamedi, M;Momma, T;Shoji, S;Osaka, T
Electrochemistry73(5)p.346 - 3512005年05月-2005年05月
概要：This work studied the design, fabrication, and performance evaluation of a novel micro direct methanol fuel cell (μDMFC). A μ-DMFC of 0.018 cm 2 active area was prepared using a series of fabrication steps from micromachined silicon wafer including photolithography, deep reactive ion etching, and electron beam deposition. The novelty of this structure is that we have integrated the anodic and cathodic micro-channels arranged in plane onto a single silicon substrate. This architecture eliminates the need for the membrane electrode assembly (MEA) used in traditional polymer electrolyte-based fuel cells. Another original aspect is the successful electroplating of Pt and Pt-Ru catalysts in the microchannels. In addition, quasi-reference electrodes could be built in the prototype cell. The experimental trials were to verify the feasibility of this novel structure on basis of MEMS technology. The fuel and oxidant were supplied to the unit cell at a rate of 10 μL/min. Preliminary test results were able to confirm that this new concept of μDMFC generates electricity. At ambient temperature under atmospheric pressure, the maximum power density was 0.44 mW/cm2 at 3 mA/cm2 with Pt anode catalyst, while the maximum power density reached 0.78 mW/cm2 at 3.6 mA/cm2 for cell with Pt-Ru anode catalyst.
Mukaibo, H;Momma, T;Mohamedi, M;Osaka, T
Journal of the Electrochemical Society152(3)p.A560 - A5652005年04月-2005年04月
概要：Nanosized electrodeposited 62 atom % Sn-Ni alloy was tested to highlight the effects of volume changes on the cycling life of the electrode during lithiation and delithiation. X-ray diffraction showed that the Ni 3Sn4 was the main phase of the as-deposited alloy. A unique feature of the 62 atom % Sn-Ni is that it exhibited a capacity recovery upon cycling. When cycled galvanostatically, the Sn62Ni38 offers low capacity fade while reversibly incorporating lithium up to 600 mAh/g. At the first charge LiSn alloy phases are formed. This led to volume expansion of the electrode causing the formation of cracks. At the following cycles the Ni3Sn4, phase was restored and preserved over extensive cycling revealing the reversibility of the reaction between Ni 3Sn4, and Li+. As to the reasons of the capacity recovery noticed with this alloy, scanning electron microscopy images provided evidence of modifications of the surface condition accompanying a volume change during cycling. The chemical diffusion coefficient (D Li) value determined from electrochemical impedence spectroscopy measurements during lithium insertion was within 10-9 to 10 -10 cm2 s-1. © 2005 The Electrochemical Society. All rights reserved.
Micro Total Analysis Systems - Proceedings of MicroTAS 2005 Conference: 9th International Conference on Miniaturized Systems for Chemistry and Life Sciences1p.1212 - 12142005年01月-2005年01月
概要：A MEMS based micro direct methanol fuel cell (μ DMFC) was realized on the plastic substrate. Hot embossing is utilized to fabricate the polymer micro channels, and spray coating method is applied to fabricate 3-D micro electrodes structure on the polymer substrate. Power generation was conformed with the first prototype μ DMFC device. Copyright © 2005 by the Transducer Research Foundation, Inc.
Yamauchi, Y;Momma, T;Kitoh, H;Osaka, T;Kuroda, K
ELECTROCHEMISTRY COMMUNICATIONS7(12)p.1364 - 13702005年-2005年
概要：We have proposed a novel convenient pathway via solvent-evaporation- mediated direct physical casting (SEDPC) for the fabrication of mesoporous metals in a micrometer scale. We have presented the successful deposition of highly ordered mesoporous Pt into micrometer channels prepared by lithography. The direct observation by a high-resolution scanning microscope (HR-SEM) showed the formation of highly ordered 2D-hexagonal (p6mm) mesoporous metals onto such substrates. The cyclic voltammogram of the mesoporous Pt in sulfuric acid revealed a typical feature which can identify the clean Pt surface. Moreover, mesoporous Pt exhibits an effective reduction of dissolved dioxygen molecules. It is proved that mesoporous Pt deposited in a very confined area via the SEDPC method possesses electrocatalytic performance owing to Pt. © 2005 Elsevier B.V. All rights reserved.
Yamauchi, Y;Yokoshima, T;Momma, T;Osaka, T;Kuroda, K
ELECTROCHEMICAL AND SOLID STATE LETTERS8(10)p.C141 - C1442005年-2005年
概要：Nickel particles with a highly ordered mesostructure are prepared by electroless deposition of Ni salts dissolved in aqueous domains of lyotropic liquid crystalline (LLC) media made of a nonionic surfactant (Brij 56) at a high concentration. The mesostructure inside the Ni particles after the electroless deposition has a macroscopic alignment of mesochannels derived from the LLC media which are composed of crystalline domains on a micrometer scale. It is proved that the arrangements of rod-like self-assemblies in the LLC indeed work as a scaffold to direct the grain growth of Ni. This is the first direct evidence of direct physical casting from LLC. © 2005 The Electrochemical Society. All rights reserved.
Motokawa, S;Obata, H;Mohamedi, M;Momma, T;Shoji, S;Osaka, T
ELECTROCHEMISTRY73(5)p.352 - 3552005年-2005年
概要：In this paper, we discussed the fabrication of micro-channel electrodes for very small DMFC (direct methanol fuel cell), i.e., μ-DMFC, where the channels composed of a current collector and a catalyst layer. The micro-channel electrodes were fabricated on a silicon wafer with a combination of photolithography, chemical etching with potassium hydroxide, spray coating, and electrodeposition method. The catalyst layer formation of Pt and PtRu was achieved by combining pulse electrodeposition with direct current electrodeposition. From these new processes, the μ-DMFC single unit cell was able to be operated for longer time operation compared with that of prototype test cell which was already reported in the previous paper.
Chemistry Letters33(12)p.1576 - 15772004年12月-2004年12月
概要：By a contact plating technique using a galvanic reaction between Al and Au in the presence of Pt complex, we have for the first time succeeded in the formation of a highly ordered mesostructured Pt film on a Au surface by reduction of Pt ions in the presence of lyotropic liquid crystals. Copyright © 2004 The Chemical Society of Japan.
Journal of Materials Chemistry14(19)p.2935 - 29402004年10月-2004年10月
概要：Mesostructured binary Ni-Co alloys with various compositions are prepared for the first time by the electroless deposition of metal salts (nickel and cobalt) dissolved in aqueous domains of the lyotropic liquid crystalline phases of a non-ionic surfactant (Brij 56) at high concentrations. Mesostructured alloys with various Ni/Co ratios are easily obtained by changing the composition of the baths, leading to the control of saturation magnetization. The composition of the alloys affects the ordering of the mesostructure; higher Co content lowers the ordering.
Shimizu, T;Momma, T;Mohamedi, M;Osaka, T;Sarangapani, S
Journal of Power Sources137(2)p.277 - 2832004年10月-2004年10月
概要：This work studied the design, fabrication, and performance evaluation of a 36 cm2, passive, air-breathing, room-temperature, direct methanol fuel cell (DMFC). The cell is completely passive with no external pumps or other ancillary devices. It takes oxygen from the surrounding air, and the methanol solution is stored in a built-in reservoir. The fuel cell runs successfully with methanol concentration ranging from 0.5 to 4 M. It produced a power density of 11 mW cm-2 reached with 4 M methanol at current densities as high as 36 mA cm-2 and at a voltage of 0.3. © 2004 Elsevier B.V. All rights reserved.
Shimizu, T;Mohamedi, M;Momma, T;Osaka, T
Electrochemistry72(9)p.637 - 6402004年09月-2004年09月
概要：In this work, we describe the fabrication of a room temperature operating direct methanol fuel cell (DMFC) device for portable electronic devices and its performance as an electrical power source for portable phone. The cell stack is completely passive without external pumps or other ancillary devices. It takes oxygen from the surrounding air, whereas the methanol solution is stored in a built-in reservoir. We achieved a maximum power as high as 2 W, which is largely commensurate with cell phone requirements. The DMFC coupled to DC-to-DC converter was capable of powering a cell phone. The maximum power consumption for talk mode was of 1.2 W while 1.8 W was withdrawn from the stack when receiving a call.
Motokawa, S;Mohamedi, M;Momma, T;Shoji, S;Osaka, T
Electrochemistry Communications6(6)p.562 - 5652004年06月-2004年06月
概要：A design for a novel micro direct methanol fuel cell (μ-DMFC) of 0.018 cm2 active area is described. The μ-DMFC was prepared using a series of fabrication steps from micro-machined silicon wafer including photolithography, deep reactive ion etching, and electron beam deposition. The novelty of this structure is that we have fabricated the anodic and cathodic micro-channels arranged in plane, dissimilar to the conventional bipolar structure. The first objective of the experimental trials was to verify the feasibility of this novel structure on basis of MEMS technology. Preliminary testing results show that this new concept μ-DMFC generates electricity. © 2004 Elsevier B.V. All rights reserved.
Chemistry Letters33(5)p.542 - 5432004年05月-2004年05月
概要：Highly ordered mesoporous Ni particles have been prepared by electroless deposition using lyotropic liquid crystals as templates. The bath conditions, in particular the kind of the reducing agents, greatly affected the degree of the ordering of mesostructures. By using well chosen appropriate reducing agents and combining those agents, we have succeeded in synthesizing Ni particles with highly ordered mesoporosity.
Passerini, S;Lisi, M;Momma, T;Ito, H;Shimizu, T;Osaka, T
Journal of the Electrochemical Society151(4)p.A578 - A5822004年05月-2004年05月
概要：In this work, the co-continuous polymer blend was synthesized for use as the electrolyte in lithium batteries. Such electrolytes were characterized by a co-continuous morphology consisting of two three-dimensionally interpenetrated polymer networks simply formed by hot-mixing two nonmiscible polymers. A preliminary electrochemical characterization of the gelified co-continuous polymer blend as electrolyte for lithium batteries is also reported. © 2004 The Electrochemical Society.
Momma, T;Ito, H;Nara, H;Mukaibo, H;Passerini, S;Osaka, T
Electrochemistry71(12)p.1182 - 11862003年12月-2003年12月
概要：We propose a polymer blending method for preparing the PEO (polyethylene oxide)-LiBF 4 complex electrolyte for lithium secondary battery applying to the IPN (interpenetrated polymer network) gel electrolyte. The polymer blend mixture of PEO-PS (polystyrene)-LiBF 4 was prepared as a film by the hot-pressing method. The resulting IPN film was plasticized with the electrolyte solution of 0.5 M LiBF 4/EC(ethylene carbonate)-PC(propylene carbonate) (1 : 1 vol.), in which the formation of PEO-LiBF 4 complex was confirmed by the Raman spectroscopy. The basic properties as an electrolyte of Li metal batteries, i.e., ionic conductivity, chemical stability at the polymer gel electrolyte/lithium metal interface, and charge-discharge performance of the Li/(PEO-LiBF 4/PS) gel electrolyte/LiCoO 2 cell were studied and discussed.
Mukaibo, H;Sumi, T;Yokoshima, T;Momma, T;Osaka, T
Electrochemical and Solid-State Letters6(10)p.A218 - A2202003年10月-2003年10月
概要：Thin Sn-Ni alloy films containing various Sn/Ni ratios were prepared by electrodeposition and characterized as lithium-ion secondary battery anodes. The initial drop in discharge capacity varied with the Sn content of the sample; i.e., for samples with 54 atom % Sn and 62 atom % Sn, the drop was less than 100 mAh/g, whereas for those with 84 atom % Sn and 92 atom % Sn, the drop exceeded 500 mAh/g. Among these thin films, the 62 atom % Sn film showed the highest reversible capacity of ca. 650 mAh/g at about the 70th cycle, whereas the other samples (54 atom % Sn, 84 atom % Sn, 92 atom % Sn) showed a capacity of 300 mAh/g. © 2003 The Electrochemical Society.
Journal of Power Sources119-121p.60 - 632003年06月-2003年06月
概要：We have proposed SnS2 as promising Li-ion battery anode materials in our previous study. Nanoparticles of this material were synthesized by a sonochemical method. In this work, smaller SnS2 particles were obtained by diluting the starting solution of the synthesis, and particles of 30nm were observed in the Field Emission SEM (FE-SEM) images. From such SnS2 particles, higher discharge capacity of 620 mAh/g and suppressed electrode degradation were observed in charge-discharge experiments. This indicates that the enlargement of the surface area was effective in facilitating the Li-ion diffusion through the active material, in simplifying the electrochemical reaction and in restraining the stress within the electrode, caused during charge and discharge. The discharge capacity in the 30th cycle was improved from 319 to 404 mAh/g by annealing the sample. It is suggested that this may be due to the change in its structure. © 2003 Elsevier Science B.V. All rights reserved.
Osaka, T;Nakade, S;Rajamaki, M;Momma, T
JOURNAL OF POWER SOURCES119p.929 - 9332003年-2003年
概要：The impedance spectrum of prismatic commercial Li-ion batteries is measured at various states of charge before and after the charge-discharge cycles and storage. The measured impedance is interpreted with a previously proposed equivalent circuit made up of anode and cathode in which the cathode component is composed of two particle size factors. The values corresponding to the characteristics of both electrodes are obtained by a fitting technique. The obtained values suggest that the capacity fade of the Li-ion battery due to the cycles is mainly caused by the increase of interfacial resistance of the cathode and a decrease in the anode capacity. These results suggest the validity of the equivalent circuit to interpret the causes of capacity fade. © 2003 Elsevier Science B.V. All rights reserved.
Mukaibo, H;Yoshizawa, A;Momma, T;Osaka, T
JOURNAL OF POWER SOURCES119p.60 - 632003年-2003年
Momma, T;Naruhashi, T;Shimizu, T;Osaka, T
Electrochemistry70(12)p.994 - 9972002年12月-2002年12月
概要：In order to realize an electrolyte membrane for DMFC having low methanol permeability, addition of ionic conductivity by the introduction of polypyrrole into engineering polymers was attempted. By the chemical oxidation of pyrrole monomer inside the polymer matrix, the composite films of polypyrrole (PPy) and engineering plastics were prepared. By the PPy introduction to poly(ethyleneterephthalate) (PET) the ionic conductivity across the film was increased. Methanol permeability was also examined to assess the performance of the film as the DMFC electrolyte. The composite film of PPy/PET, which was formed by pyrrole oxidation, showed better performance of high ionic conductivity and low methanol permeability.
Shimizu, T;Naruhashi, T;Momma, T;Osaka, T
ELECTROCHEMISTRY70(12)p.991 - 9932002年-2002年
概要：In order to realize an electrolyte membrane for DMFC having low methanol permeability, suppression of methanol permeability of Nafion by introducing polyaniline (PAn) was attempted. The membrane obtained by the electropolymerization of aniline at Nafion-coated Pt electrode had bi-layered morphology, and it showed lower ionic conductivity and lower methanol permeability compared with those of Nafion, compared to PAn introduced Nafion membrane by the chemical oxidative polymerization of aniline in Nafion. The PAn introduced Nafion by chemical oxidative polymerization showed superior characteristics to Nafion from the viewpoint of conductivity and methanol permeability.
Journal of Power Sources97-98p.198 - 2002001年07月-2001年07月
概要：SnS2 powder made by sonochemistry was applied and examined for anode material of Li ion battery. The annealed SnS2 at 400°C showed a higher capacity of 600 mAh g-1 than the non-annealed SnS2. The cell with annealed SnS2 anode and LiCoO2 cathode worked well. From the results, SnS2 material was revealed to be one of the candidates of the anode materials for future Li ion batteries. © 2001 Elsevier Science B.V.
Osaka, T;Momma, T
Journal of Power Sources97-98p.765 - 7672001年07月-2001年07月
概要：The recent technological trends in the field of lithium ion polymer battery are discussed. Since its introduction, the energy density of the Li ion battery has slowly grown. Simultaneous to this is the development of a new type of battery, known as the Li ion polymer battery, with flexible light features. Efforts are underway to realize a battery with the anode of Li metal, with particular emphasis on safety.
Kuwahara, T;Yamakawa, N;Momma, T;Osaka, T
ELECTROCHEMISTRY69(8)p.598 - 6022001年-2001年
概要：A potentiometric acetylcholine microsensor was fabricated by use of a composite film consisting of polyion complex (PIC), which consisted with acetylcholine esterase (AChE), and the electrochemically inactive poly-1-aminopyrrole (iPAPy). The iPAPy-PIC (AChE) composite film on Pt electrode displayed potential response to acetylcholine concentration owing to pH change during the enzymatic reaction, where the product contains weak acid CH3COOH. The sensitivity of the iPAPy-PIC (AChE) electrode clearly demonstrated higher sensitivity with low detection limit (1 × 10-6 mol dm-3) than that of the iPPy-PIC (AChE) electrode of detection limit (1 × 10-5 mol dm-3). The mechanism of increasing the sensitivity of iPAPy-PIC (AChE) electrode was discussed the interaction of -NH2 of iPAPy with CH3 COOH, which would accelerate the dissociation of weak acid CH3COOH.
Passerini, S;Alessandrini, F;Momma, T;Ohta, H;Ito, H;Osaka, T
ELECTROCHEMICAL AND SOLID STATE LETTERS4(8)p.A124 - A1262001年-2001年
概要：In this work we report the synthesis and characterization of gel-polymer electrolytes based on co-continuous polymer blends. Such blends are characterized by a bicontinuous morphology consisting of two three-dimensionally interpenetrated polymer networks. Co-continuous polymer blends are simply formed by hot-blending two immiscible polymers. The intrinsic advantage of co-continuous polymer blends consists in the possibility of selecting the polymers. One polymer (e.g., polystyrene) imparts the desired mechanical properties and the other polymer [e.g., poly(ethylene oxide)] enables the ionic conductivity via formation of a gel which contains the electrolytic solution.
Chusid, O;Gofer, Y;Aurbach, D;Watanabe, M;Momma, T;Osaka, T
JOURNAL OF POWER SOURCES97-8p.632 - 6362001年-2001年
概要：This paper describes studies of the interface between lithium electrodes and solid electrolyte systems using in situ FTIR spectroscopy in a single internal reflectance mode. In this method, the masking effect of the electrolyte matrix components is largely avoided. We studied gel electrolytes based on polyvinylidene difluoride-hexafluoropropylene with cyclic alkyl carbonates as plasticizers, suitable for ambient temperatures, and a solvent free polymer, derivatives of polyethylene oxide (PEO) with a branched structure: poly[ethyleneoxide-2-(2-methoxyethoxy)ethyl glycidyl ether] at elevated temperatures. We found that the surface chemistry of Li electrodes in contact with the gel matrixes is dominated by alkyl carbonate solvent reduction to ROCO2Li surface species. In the case of the PEO-based polymer, the surface reactions of Li electrodes are dominated by salt and trace water reduction. The polymer itself seems to be stable with lithium even at 60°C. © 2001 Elsevier Science B.V.
Momma, T;Shiraishi, N;Yoshizawa, A;Osaka, T;Gedanken, A;Zhu, JJ;Sominski, L
JOURNAL OF POWER SOURCES97-8p.198 - 2002001年-2001年
IEEE Transactions on Magnetics35(5 PART 1)p.2499 - 25011999年12月-1999年12月
概要：In order to increase the resistivity of electrodeposited high BS CoNiFe thin film, the effect of an organic additive such as diethylenetriamine (DET) added to the plating bath was investigated. The values of ρ and HC, were gradually increased as a function of DET concentration. The desirable soft magnetic CoNiFe thin film with ρ = 25-90 μΩ-cm under the conditions of BS > 1.9 T and HC < 2.5 Oe was developed as function of carbon in the deposited films. Additionally, the high resistivity CoNiFe thin film with ρ = 130 μΩ-cm was established under the conditions of BS= 1.7 T and HC < 6 Oe. © 1999 IEEE.
Electrochemistry67(12)p.1150 - 11521999年12月-1999年12月
概要：Formation of Ni microstructure with high aspect ratio without thicker photoresist was tried by an electrcdeposition method. The Ni microprobes thicker than photoresist thickness were electrodeposited on a patterned substrate using thin photoresist patterned with UV radiation. It was important for preparing Ni microprobe with high aspect ratio to keep the overpotential of patterned cathode higher, and moreover the agitation using a paddle plating cell system was so effective to form uniform microprobes.
Electrochemistry67(3)p.238 - 2421999年12月-1999年12月
概要：For alkaline batteries, it is important to investigate prospective materials with higher energy density and lower cost. We paid attention to the reaction of quinone compounds and investigated the electrochemical properties of these compounds in alkaline solution and discussed the possibility for a negative active material of alkaline secondary batteries. In alkaline solution, most of these materials, e.g. p-benzoquinone, dissolved, while only chloranilic acid (C6Cl2(OH)2O2) did not. We have found that chloranilic acid is the most possible candidate for the negative active materials of alkaline batteries because of its insolubility to alkaline solutions. There were three couples of peaks in cyclic voltammogram (-1.2 to approximately -0.1 V vs. Ag/AgCl) for the electrode of chloranilic acid. With cathodic scan of cyclic voltammogram on -0.8 V vs. Ag/AgCl, the color of solution changed. It seems that this change is caused by the influence of dissolved products, which was formed by electrochemical redox reaction of chloranilic acid around -1.0 V vs. Ag/AgCl. When the charge-discharge test was conducted in the potential range between -0.45 V and -0.8 V, no colored substance was formed in the solution and the discharge capacity reached to approximate 150 mAh g-1 at the first cycle. From these results, on chloranilic acid, it was suggested that there was a possibility of application for a negative active material of alkaline secondary batteries.
The 196th Meeting, Electrochemical Souity1999年10月-
The 50th Meeting, International Society of Elecctochemistry1999年09月-
The 2nd International Conference on Application of Conducting Polymers1999年07月-
Journal of the Electrochemical Society146(6)p.2092 - 20961999年06月-1999年06月
概要：The corrosion resistance of soft magnetic films is an important property to be considered in the manufacture of magnetic devices. We investigated the corrosion behavior of the electrodeposited CoNiFe film with desired soft magnetic properties by varying the crystalline structure and the amount of included sulfur. The corrosion property in 2.5% NaCl solution depends largely on the sulfur content and also on the structure of the film. Although the CoNiFe film contains more than 13 atom % Fe, the film of face-centered to body-centered cubic mixed crystals exhibits a high anticorrosion property because of very small grain size with essentially no sulfur inclusion (<0.1 atom %).
The 3rd Korea-Japan Joint Seminar on Advanced Batteries1999年06月-
1999 IEEE International Magnetics Conference（Intermag'99)1999年05月-
Electrochemical and Solid-State Letters2(5)p.215 - 2171999年05月-1999年05月
概要：The performance of a lithium metal anode was studied in a poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) gel electrolyte. By using the PVdF-HFP gel electrolyte, we obtained a higher coulombic efficiency (ca. 85%) and a more uniform morphology of the lithium metal anode than those obtained with the propylene carbonate liquid or the poly(ethylene oxide) gel system. Additionally, the CO2 addition to the PVdF-HFP gel system improved both the uniformity in morphology of the lithium anode and the coulombic efficiency further to ca. 95%.
Journal of Electrochemical Society.146;5, pp.1724-17291999年05月-
Osaka, T;Kitahara, M;Uchida, Y;Momma, T;Nishimura, K
JOURNAL OF POWER SOURCES81p.734 - 7381999年-1999年
Sugai, Y;Asa, F;Okada, Y;Yokoshima, T;Momma, T;Osaka, T;Ito, T
ELECTROCHEMISTRY67(12)p.1150 - 11521999年-1999年
Momma, T;Komaba, S;Osaka, T
Denki Kagaku65(2)p.115 - 1201997年12月-1997年12月
概要：The energy and power densities of electric double layer capacitor were calculated in order to estimate the possibility of its application to the pulse power supply for an electric vehicle. The model capacitor is composed of a stack of cell unit simply assembled with bipolar module with the physical and electrochemical properties of aqueous or organic electrolytes. The calculation was done with the variations of cell numbers and the roughness of electrode where the roughness is assumed to be the ratio of real surface area to flat surface area. The resultant energy densities of models showed that the capacitor using organic electrolyte had a merit of high energy density caused by the wide potential window of organic electrolyte. The results of power density under the 30 s full discharge suggested that aqueous electrolyte gave high power density to the capacitor while organic electrolyte lower power output because of the high resistance of the electrolyte solution. Moreover, the power densities of capacitors with organic and aqueous electrolytes showed maximum and sharp decline with an increase in cell stacked number due to the increase of capacitor resistance. From the results, it is suggested that the development of new components and cell construction should be demanded for capacitor with organic electrolyte.
Electronic and Parts Materials36;11,pp40-441997年11月-
Journal of Power Sources68(2)p.392 - 3961997年10月-1997年10月
概要：Poly (methylmethacrylate) (PMMA) - and poly (acrylonitrile) (PAN)-based gel electrolytes were applied to Li/polypyrrole ( PPy ) battery and its performance was investigated. These batteries showed excellent performance with 3 V output voltage and 90-100% coulombic efficiency. Using chemically more stable PMMA gel electrolyte, long charge/discharge cycle life more than 8000 cycles at 0.1 mA cm-2 was obtained. © 1997 Elsevier Science S.A.
The Electrochemical Society TC local section1997年06月-
Osaka, T;Momma, T;Matsumoto, Y;Uchida, Y
Journal of the Electrochemical Society144(5)p.1709 - 17131997年05月-1997年05月
概要：Electrodeposited lithium produced with and without CO2 in LiClO4/propylene carbonate electrolytes was investigated for charge-discharge cycleability, surface morphology, and composition of the surface layer. The addition of CO2 in the electrolyte enhances the cycleability, produces smoother surface morphology, and forms Li2CO3 in the inner region of the surface film. This paper describes experimental results showing those three different effects of CO2 addition, and discusses the interrelation among them.
191st Meeting of the Electrochemical Society1997年05月-
Osaka, T;Komaba, S;Fujihana, K;Okamoto, N;Momma, T;Kaneko, N
Journal of the Electrochemical Society144;2,pp742-748(2)p.742 - 7481997年02月-1997年
Osaka, T;Homma, T;Momma, T;Yarimizu, H
Journal of Electroanalytical Chemistry421(1-2)p.153 - 1561997年01月-1997年01月
概要：Deposition processes of lithium in solid polymer [poly(ethylene oxide) (PEO)8 + LiClO4] and gel [PEO8 + propylene carbonate(PC) + LiClO4] electrolytes, as well as in the liquid (PC + LiClO4) one, were observed in situ using an optical microscope and their difference is discussed. It was confirmed that the dendritic growth of lithium, which appeared in the liquid electrolyte, is suppressed in the solid polymer due to the immobility of the electrolyte molecules, although non-uniform coverage of the cathode was observed because of its low conductivity. In contrast, the gel electrolyte possessed advantages of both the liquid and solid electrolytes, resulting in a smooth and uniform deposition in the current density region up to 2.0mAcm-2.
Electrochemica Acta42(3)p.383 - 3881997年-
Osaka, T;Momma, T;Matsumoto, Y;Uchida, Y
JOURNAL OF POWER SOURCES68(2)p.497 - 5001997年-1997年
Komaba, S;Seyama, M;Momma, T;Osaka, T
ELECTROCHIMICA ACTA42(3)p.383 - 3881997年-1997年
Komaba, S;Momma, T;Usui, A;Osaka, T
DENKI KAGAKU65(3)p.204 - 2071997年-1997年
Liu, XJ;Momma, T;Osaka, T
Denki Kagaku64(7)p.831 - 8351996年12月-1996年12月
概要：Double layer capacitance of phenoric-resin based active carbon fiber (ACF) electrode was enhanced by a method of electrochemical treatment in various acidic electrolytes. Oxidic acids, especially perchloric acid solution, showed higher enhancement of the ACF capacitance by the electrochemical treatment. Thus, the capacitor was constructed with using 1.0 mol dnr3 HC1O4 electrolyte solution and ACF electrode oxidized at 1.0 V vs. SCE for 1 h. The capacitor gives charging-discharging characteristics better than that of HzSCh electrolyte system.
Chemistry Letters(8)p.625 - 6261996年12月-1996年12月
概要：Isotropic high density graphite (HDG) was used as the polarizable electrode of electric double layer capacitors (EDLC) with a solid electrolyte consisting of PEO/LiClO4([EO]/[Li+] = 8:1) at 80 °C or with a gel electrolyte consisting of PEO/ PC/LiClO4 ([EO]/[PC]/|Li+] = 8:8:1) at room temperature. The all-solid state capacitor with HDG electrodes works satisfactorily as a EDLC with a relatively high capacitance, as well as the EDLC with gel electrolyte PEO/PC/LiClO4. These EDLCs with solid polymer electrolyte PEO/LiClO4 and gel electrolyte PEO/PC/LiClO4 show good charge/discharge behavior when charged to 1.5 V at 80 °C and 20 °C, respectively.
Momma, T;Liu, XJ;Osaka, T;Ushio, Y;Sawada, Y
Journal of Power Sources60(2)p.249 - 2531996年06月-1996年06月
概要：Electrochemical oxidation of an active carbon fiber (ACF) electrode showed an enhancement effect of the electrode capacitance. The modification of ACF, however, increased the electrode inner resistance with an increase in the capacitance. Au deposition, the deaeration and the electrochemical reduction (discharge) after the modification showed a decrease in the inner resistance. Thus, the capacitor using the modified ACF electrodes with deaeration, Au deposition and/or discharge treatment showed an enhancement of capacitance with decreasing inner resistance.
Momma, T;Yamamoto, M;Komaba, S;Osaka, T
Journal of Electroanalytical Chemistry407(1-2)p.91 - 961996年05月-1996年05月
概要：By coating an electroactive polypyrrole (PPy) film electrode with a plasticized poly(vinyl chloride) (PVC) membrane containing valinomycin, an all-solid-state potassium-selective electrode was fabricated. The polymerizing conditions of the PPy film were optimized for stable ionic responses. The electrochemical characteristics of these electrode systems were evaluated by an a.c. impedance method with respect to the mechanism of potential drift. The steady-state response over several days, which depended on the electrode configuration, was related to the impedance behavior of the electrode systems.
Liu, XJ;Momma, T;Osaka, T
DENKI KAGAKU64(2)p.143 - 1481996年-1996年
Materials Research Society Symposium - Proceedings393p.223 - 2281995年12月-1995年12月
概要：The lithium metal anode electrodeposited on nickel was studied by charge-discharge test coupled with in-situ ac impedance measurement. The test gives information about lithium anode interface and the modified interface of electrodeposited lithium by CO2 is confirmed to enhance the lithium cycleability. Also the CO2 protects the lithium interface in the presence of H2O impurity during cycling test.
OGASAWARA, K;MOMMA, T;OSAKA, T
Journal of the Electrochemical Society142(6)p.1874 - 18801995年06月-1995年06月
概要：In a study of the electroluminescence (EL) of porous silicon on an n-type Si wafer using an S2O8 2- electrolyte solution, the addition of C2H5OH to the solution was found to enhance the intensity of EL from the porous silicon. The porous silicon structure was classified into two types which were prepared based on whether the anodizing current density for forming the porous n-Si was above or below the saturated photocurrent. A single layer of fine pores was formed galvanostatically with illumination at a current density below the saturated photocurrent density, and a double layer of fine and rough pores was formed under the same conditions but at a current density above the saturated photocurrent density. The electrochemical and enhanced electroluminescent properties of the two types of porous silicon were studied.
MOMMA, T;KAKUDA, S;YARIMIZU, H;OSAKA, T
Journal of the Electrochemical Society142(6)p.1766 - 17691995年06月-1995年06月
概要：Nafion(R) was introduced into a polypyrrole (PPy) matrix, and the redox performance of the PPy/Nafion electrode was investigated in a poly(ethylene oxide) (PEO)-LiClO4 electrolyte. A rougher interface between polymer cathode and polymer electrolyte is usually needed for an all-solid battery, however, the PPy/Nafion cathode works well regardless of the flat surface of the PPy/Nafion film. When compared to a PPy film doped with ClO4 - anions with a similar morphology, the PPy/Nafion film showed better redox performance. The results of ac impedance spectroscopy and potential-step chronoamperometry confirmed that the improvement in the redox reaction of the PPy/Nafion film was due to the enhancement of the ion diffusion rate in the film. Thus, the PPy/Nafion film showed good charging-discharging properties in a rechargeable Li/PEO-LiClO4/(PPy/Nafion) battery.
KAKUDA, S;MOMMA, T;OSAKA, T;APPETECCHI, GB;SCROSATI, B
Journal of the Electrochemical Society142(1)p.L1 - L21995年01月-1995年01月
概要：An ambient-temperature, all-solid lithium battery was fabricated by combining a poly(acrylonitrile), PAN-based polymer electrolyte with a lithium metal anode and a polypyrrole, PPy, film cathode. The influence of the morphology of the PPy film cathode on the battery performance was investigated. The results show that the electrode morphology does not considerably influence the charge-discharge cycling response and that the solid-state, Li/PPy battery exhibits high coulombic efficiency, approaching 90%. However, at the present time, the battery has a poor shelf life, and work is in progress for overcoming this drawback.
Osaka, Tetsuya; Momma, Toshiyuki; Taiima, Takayuki; Matsumoto, Yasuhiro
Journal of the Electrochemical Society142(4)p.1057 - 10601995年01月-1995年01月
OSAKA, T;MOMMA, T;TAJIMA, T;MATSUMOTO, Y
JOURNAL OF THE ELECTROCHEMICAL SOCIETY142(4)p.1057 - 10601995年-1995年
MOMMA, T;KOMABA, S;YAMAMOTO, M;OSAKA, T;YAMAUCHI, S
SENSORS AND ACTUATORS B-CHEMICAL25(1-3)p.724 - 7281995年-1995年
MOMMA, T;USUI, A;OSAKA, T
RUSSIAN JOURNAL OF ELECTROCHEMISTRY31(9)p.891 - 8951995年-1995年
MOMMA, T;NISHIMURA, K;OSAKA, T;KONDO, N;NAKAMURA, S
Journal of the Electrochemical Society141(9)p.2326 - 23311994年09月-1994年09月
概要：The performance of a composite film of polypyrrole (PPy) and poly(4-styrenesulfonate) (PSS) was studied in combination with an organic electrolyte as a possible lithium battery cathode. The composite film had a fairly flat morphology and exhibited electroactivity in organic electrolyte solutions using dimethylsulfoxide and propylene carbonate (PC) solvents. We confirmed that during the redox process the film charge was compensated with cations. A lithium cell consisting of the composite film as a cathode and an LiClO4-PC electrolyte worked as a rechargeable battery. The energy density of the PPy/PSS cathode was calculated to be 220 Wh liter-1 and the average output voltage of the rechargeable cell was 2.9 V.
OSAKA, T;MOMMA, T;KOMABA, S;KANAGAWA, H;NAKAMURA, S
Journal of Electroanalytical Chemistry372(1-2)p.201 - 2071994年07月-1994年07月
概要：Insulating and electroinactive polypyrrole (PPy(NaOH)) film can be synthesized by electropolymerization from an NAOH aqueous solution containing pyrrole at a highly positive potential. The synthesis of this electroinactive PPy(NaOH) was investigated using in situ UV and X-ray photoelectron spectroscopy, and was compared with the irreversible oxidation ("overoxidation") of electroactive PPy under a highly positive potential. Overoxidation made the PPy inactive. However, the formation of PPy (NaOH) started above 0.5 V vs. Ag/AgCl, and the "overoxidation" began simultaneously in the polymerizing solution. Overoxidation with nucleophilic hydroxide ions caused a structural change in the PPy molecule, which destroyed the original π-conjugated system. © 1994.
OSAKA, T;MOMMA, T;NISHIMURA, K;KAKUDA, S;ISHII, T
JOURNAL OF THE ELECTROCHEMICAL SOCIETY141(8)p.1994 - 19981994年-1994年
概要：An all solid-state lithium/polypyrrole (PPy) battery using polyethylene oxide (PEO)-LiClO4 as a solid polymer electrolyte was assembled, and the effects of the morphology of the PPy film and the concentration of LiClO4 on battery performance were investigated. Optimum conditions for the redox properties of PPy films in PEO-LiClO4 at 80 °C were obtained with an LiClO4 concentration of n = 8 approximately 20 (n = [EO]/[Li]) when using rough PPy film. A Li/PPy battery using PEO-LiClO4 with optimized conditions exhibited high coulombic efficiency, above 90% at 0.1 mA cm-2 at 80 °C. Cyclability of 1400 cycles with high coulombic efficiency was attained.
OSAKA, T;MOMMA, T;TAJIMA, T
DENKI KAGAKU62(4)p.350 - 3511994年-1994年
OSAKA, T;MOMMA, T;TAJIMA, T;MATSUMOTO, Y
DENKI KAGAKU62(5)p.451 - 4521994年-1994年
OSAKA, T;MOMMA, T;NISHIMURA, K;TAJIMA, T
Journal of the Electrochemical Society140(10)p.2745 - 27481993年10月-1993年10月
概要：Electrodeposited lithium was evaluated by ac impedance measurement and optical microscopy in two solutions containing LiClO4; a propylene carbonate (PC) solution and a blended solution consisting of PC and 1,2-dimethoxyethane (DME) (volume ratio=1.1). The ac impedance data analyzed in the higher frequency region, where the charge-transfer resistance (Rct) of Li++e-⇔ Li can be evaluated. The value of Rct was always larger in the PC electrolyte solution than in the PPC-DME(1:1) electrolyte solution, and Rct depended on the lithium deposition charge. Microscopic observation indicated that lithium deposited more uniformly in PC-DME (1:1) than in PC solution. The results of morphological evaluation of the electrodeposited lithium using optical microscopy corresponded to the variations in the value of Rct obtained from ac impedance measurements.
OSAKA, T;MOMMA, T
Electrochimica Acta38(14)p.2011 - 20141993年01月-1993年01月
概要：The electrochemically polymerized conductive polymers were evaluated by an ac impedance measurement for use in a Li/polymer battery. The validity and the limit of ac impedance analysis for this case are discussed. © 1993.
OSAKA, T;FUKUDA, T;KANAGAWA, H;MOMMA, T;YAMAUCHI, S
Sensors and Actuators: B. Chemical13(1-3)p.205 - 2081993年01月-1993年01月
概要：On the basis of a metal/insulator/metal (MIM) device using electroinactive polypyrrole (PPy) film as an insulator, an amperometric pH sensor device for a very small test solution (4 μl) was developed using the structure of Au/PPy/Au with a window hole. Electropolymerized thin PPy film formed from alkaline solution is used for the ion-selective membrane. The Au/PPy/Au device with a d.c. voltage supply from 0 to 0.2 V works well as an amperometric pH sensor, that is, the gradient of the Cottrell plot within 10 s corresponds exactly to the pH value. © 1993.
OSAKA, T;MOMMA, T;NISHIMURA, K
DENKI KAGAKU61(7)p.722 - 7231993年-1993年
OSAKA, T;MOMMA, T;SHIOTA, K;NAKAMURA, S
DENKI KAGAKU61(12)p.1361 - 13651993年-1993年
Thin Solid Films215(2)p.200 - 2021992年08月-1992年08月
概要：The electrical conduction mechanism for the indium tin oxide (ITO)/polypyrrole (PPy)/ITO sandwich type of metal-insulator-metal element was investigated, where electroinactive PPy polymerized in aqueous NaOH solution was used as an insulator. The ITO/PPy/Au element demonstrated a non-linear J-V response exactly the same as that of the ITO/PPy/ITO element, indicating that the carriers do not come from the interface but the bulk of an insulator. For the temperature dependence of the J-V responses of the ITO/PPy/ITO element, Poole-Frenkel emission is confirmed to be a dominant conduction mechanism. The activation energy of PPy electropolymerized for 60 min was calculated to be 0.46 eV on the basis of Poole-Frenkel emission. The activation energy and the conductivity of the PPy film were dependent on polymerization time. © 1992.
OSAKA, T;NAKAJIMA, T;SHIOTA, K;MOMMA, T
Journal of the Electrochemical Society138(10)p.2853 - 28581991年10月-1991年10月
概要：Electroactive polyaniline (PAn) films were deposited from PC (propylene carbonate)-EC (ethylene carbonate) and PC-DME (1,2-dimethoxyethane) mixed polymerization solutions containing aniline, CF3COOH, and LiClO4. Higher dielectric constant solvents are necessary to deposit the PAn film where protons, dissociated from the acid, initiate the polymerization of aniline. Various PAn films deposited in the PC, the PC-EC (50 mole percent), and the PC-DME (50 volume percent) solutions were used for the cathode materials of the rechargeable lithium batteries. Charge capacity and discharge ability of the Li/PAn batteries in the PC-LiClO4 electrolyte solution are almost the same, regardless of the polymerization solvents, such as PC ≈ PC-EC ≥ PC-DME and PC-EC ≥ PC-DME ≈ PC. The mixed solvent electrolyte solution effect on the Li/PAn (polymerized in the PC solution) batteries becomes much larger such as PC-DME > PC-EC > PC. Moreover, the electrochemical kinetic factors of the PAn films deposited in the various mixed polymerization solutions and also in the different electrolytes were experimentally determined by measuring the ac impedance. The results of the ac impedance analysis of each PAn film correlate well with the battery performances of Li/PAn cells.
Toshiyuki Momma and Tetsuya Osaka
Springer Science+Business Media2013年 11月-
1章 逢坂哲彌、門間聰之、奈良洋希 ２章 門間聰之
株式会社オ ー ム 社2010年 02月-
T. Osaka, S. Komaba, T. Momma
John Wiley &Sons, Inc.2010年-
T. Osaka, T. Momma
逢坂哲彌, 跡部真人, 加納健司, 桑畑進, 立間徹, 門間聰之編 部分執筆
みみずく舎2009年 11月-2009年 11月
H. Mukaibo, T. Momma
Springer2010年 01月-2010年 01月
3rd Asian Conference on Electrohcemical Power Sources2008年11月
3rd Asian Conference on Electrohcemical Power Sources2008年11月
214th Meeting of The Electrochemical Society2008年10月
3rd German-Italian-Japanese Meeting of Electrochemists2008年05月
JST ナノテクノロジー分野別バーチャルラボ成果報告会, 東京2007年11月
第48回電池討論会, 福岡国際会議場, 福岡2007年11月
第48回電池討論会, 福岡国際会議場, 福岡2007年11月
第48回電池討論会, 福岡国際会議場, 福岡2007年11月
第48回電池討論会, 福岡国際会議場, 福岡2007年11月
第48回電池討論会, 福岡国際会議場, 福岡2007年11月
212th Meeting of the Electrochemical Society (ECS), Washington D.C2007年10月
212th Meeting of the Electrochemical Society (ECS), Washington D.C2007年10月
212th Meeting of the Electrochemical Society (ECS), Washington D.C2007年10月
日本化学会 第一回関東支部大会(2007), 首都大学東京, 東京2007年09月
2007年 電気化学会秋季大会, 東京工業大学, 東京2007年09月
2007年 電気化学会秋季大会, 東京工業大学, 東京2007年09月
International Mini-Symposium of Secondary Battery, Chungbuk Nat'l Univ.2008年12月
International Conference on Advanced Capacitors (ICAC), Kyoto, Japan2007年05月
Imternational Meeting on Lithium Battery 2008(IMLB-14)2008年06月
International Meeting on “Polymer Batteries and Fuel Cells, (PBFC-2007), CNR building, Rome, Italy2007年05月
逢坂 哲彌, 門間 聰之
黒田 一幸, 逢坂 哲彌, 門間 聰之, 横島 時彦, 滋野 哲郎
逢坂 哲彌, 庄子 習一, 門間 聰之, 本川 慎二
門間 聰之, 山内 悠輔, 黒田 一幸, 逢坂 哲彌
逢坂 哲彌, 朴 秀吉, 門間 聰之, 朴 鍾殷, 清水 貴弘, 呉 美惠
逢坂 哲彌, 門間 聰之, 朴 鍾殷
逢坂 哲彌, 門間 聰之, 平澤 賢太
門間 聰之, ソリス ホルヘ, 逢坂 哲彌
逢坂 哲彌, 門間 聰之, 巽 智香, 奈良 洋希
逢坂 哲彌, 門間 聰之, 朴 鍾殷
逢坂 哲彌, 門間 聰之, 横島 時彦, 奈良 洋希
整理番号：1187リチウム二次電池用活物質、リチウム二次電池用負極、およびリチウム二次電池（日本, PCT, アメリカ）
横島 時彦, 奈良 洋希, 逢坂 哲彌, 門間 聰之
整理番号：1246電池システムおよび電池の評価方法（日本, PCT, アメリカ）
逢坂 哲彌, 門間 聰之, 横島 時彦, 向山 大吉, 奈良 洋希
整理番号：1320電池システム及び電池システムの評価方法（日本, PCT, アメリカ）
逢坂 哲彌, 門間 聰之, 横島 時彦, 向山 大吉, 奈良 洋希
逢坂 哲彌, 門間 聰之, 横島 時彦, 奈良 洋希
整理番号：1385電気化学システム（日本, PCT, アメリカ）
奈良 洋希, 逢坂 哲彌, 門間 聰之, 横島 時彦, 向山 大吉
奈良 洋希, 逢坂 哲彌, 門間 聰之, 横島 時彦
逢坂 哲彌, 門間 聰之, 横島 時彦, 奈良 洋希
門間 聰之, 逢坂 哲彌, ウ ユンエン, 横島 時彦, 奈良 洋希
門間 聰之, 逢坂 哲彌, 横島 時彦, 奈良 洋希
逢坂 哲彌, 門間 聰之, 横島 時彦, 向山 大吉, 奈良 洋希
逢坂 哲彌, 秀島 翔, 門間 聰之, 林 宏樹
逢坂 哲彌, 門間 聰之, 中村 夏希, 三栗谷 仁
研究成果概要：Li空気電池において大気中から侵入するH2O、CO2、N2、Ar等の影響を検討した。電解液中のH2O量が少ない場合のクーロン効率は55 %を示す一方、CO2およびH2Oが共存した場合、クーロン効率は最大約90 %に達した。Li空気...Li空気電池において大気中から侵入するH2O、CO2、N2、Ar等の影響を検討した。電解液中のH2O量が少ない場合のクーロン効率は55 %を示す一方、CO2およびH2Oが共存した場合、クーロン効率は最大約90 %に達した。Li空気電池の電解液として広く研究されているDMSOはLi負極のクーロン効率が低いとされているが、SEI表面および内部を無機層で構成することでクーロン効率が85 %以上になることも見出した。
|Graduation Thesis A||先進理工学部||2020||秋学期|
|Graduation Thesis B||先進理工学部||2020||春学期|
|Field work in Research Institutions and Industry||先進理工学部||2020||集中講義（秋学期）|
|Field work in Research Institutions and Industry||先進理工学部||2020||集中講義（秋学期）|
|Research on Applied Electrochemistry||大学院先進理工学研究科||2020||通年|
|Advanced Physical Chemistry A||大学院先進理工学研究科||2020||春学期|
|Seminar on Applied Physical Chemistry A||大学院先進理工学研究科||2020||春学期|
|Seminar on Applied Physical Chemistry B||大学院先進理工学研究科||2020||秋学期|
|Research on Electrochemical Nano-Systems||大学院先進理工学研究科||2020||通年|
|Experiments in Nanoscience and Nanoengineering||大学院先進理工学研究科||2020||通年|
|Seminar on Nano-Electrochemistry A||大学院先進理工学研究科||2020||春学期|
|Seminar on Nano-Electrochemistry B||大学院先進理工学研究科||2020||秋学期|
|Seminar on Nano-Electrochemistry C||大学院先進理工学研究科||2020||春学期|
|Seminar on Nano-Electrochemistry D||大学院先進理工学研究科||2020||秋学期|
|Master's Thesis (Department of Applied Chemistry)||大学院先進理工学研究科||2020||通年|
|Master's Thesis (Department of Nanoscience and Nanoengineering)||大学院先進理工学研究科||2020||通年|
|Assessment and Design of Chemical Technologies I||大学院先進理工学研究科||2020||集中講義（秋学期）|
|Assessment and Design of Chemical Technologies I||大学院先進理工学研究科||2020||集中講義（秋学期）|
|Assessment and Design of Chemical Technologies II||大学院先進理工学研究科||2020||集中講義（春学期）|
|Assessment and Design of Chemical Technologies II||大学院先進理工学研究科||2020||集中講義（春学期）|
|応用化学研究Ｂ 門間 聰之||大学院先進理工学研究科||2020||通年|
概要：電気化学の理論、測定法、応用に関する教科書を分担執筆。分担箇所 4章電気化学反応速度（p44-55）５章電気化学反応における物質移動（ｐ56-64）６章電気化学測定のうち6.1〜6.3および6.5（p65-77, 90-93）