Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
早期公開論文
早期公開論文の12件中1~12を表示しています
  • Lu YIN, Ryoichi TATARA, Shogo YAMAZAKI, Rena TAKAISHI, Eisuke SHIIYAMA ...
    論文ID: 23-00048
    発行日: 2023年
    [早期公開] 公開日: 2023/06/06
    ジャーナル オープンアクセス 早期公開
    電子付録
  • Tatsuya OKAYAMA, Hiro MINAMIMOTO, Minoru MIZUHATA
    論文ID: 23-00047
    発行日: 2023年
    [早期公開] 公開日: 2023/05/23
    ジャーナル オープンアクセス 早期公開

    The Ni-Al layered double hydroxide materials with high crystallinity were synthesized by the room-temperature liquid process and applied as oxygen evolution reaction (OER) catalysts. It is interesting to note that the OER activity was found to be relatively high in comparison with the Ni-based materials. In addition, the structural analyses and the effects of interlayer anion specie on the OER activity were also evaluated. It was found that the changes in the interlayer anion species from F to OH resulted in the enhancement of the OER activity. The maintained crystallinity after the electrochemical measurements were also observed through the X-ray analyses. The present work provides the insights about the possibility of the well-defined structures as the electrodes which were prepared by the unique liquid phase process.

  • Yuki FUJII, Ryoichi TATARA, Daisuke IGARASHI, Tomooki HOSAKA, Rena TAK ...
    論文ID: 23-00051
    発行日: 2023年
    [早期公開] 公開日: 2023/06/03
    ジャーナル オープンアクセス 早期公開
    電子付録
  • Yoichiro KAWANO, Akihiko KATO, Hiroyuki USUI, Yasuhiro DOMI, Hiroki SA ...
    論文ID: 23-00023
    発行日: 2023年
    [早期公開] 公開日: 2023/05/18
    ジャーナル オープンアクセス 早期公開
    J-STAGE Data

    We have been developing sintered multilayer oxide-based all-solid-state batteries. Anode active material rutile-type TiO2 was not reacted with amorphous Na superionic conductor (NASICON)-type solid electrolyte Li1.5Al0.5Ge1.5(PO4)3 (LAGP) even after sintered at 600 °C in a nitrogen atmosphere from the XRD patterns. The charge/discharge behavior of the electrochemical measuring cell (when using a non-aqueous electrolyte) was not different from that of rutile-type TiO2. However, anatase-type TiO2 charge/discharge behavior changed after sintering process. Additionally, in the result of the input/output characteristics using multilayer oxide-based all-solid-state battery, rutile-type TiO2 as anode material was 3 times higher discharge capacity than anatase-type TiO2 at current value 25.6 µA mm−2. Finally, we successfully measured the Raman spectroscopy of all-solid-battery and rutile-type TiO2 Raman shift peaks were reversibility during charge/discharge. Based on these findings, we conclude that rutile-type TiO2 maintained a strong crystalline structure and high Li diffusivity even when sintered with amorphous LAGP. It suggested that rutile-type TiO2 is suitable as anode material for oxide-based all-solid-state batteries requiring the sintering process.

  • Xiankui WEN, Jingliang ZHONG, Xiang LI, Zhicheng LIN, Luyan WANG, Qian ...
    論文ID: 23-00038
    発行日: 2023年
    [早期公開] 公開日: 2023/05/27
    ジャーナル オープンアクセス 早期公開
  • Takeshi TONOYA, Yukiko MATSUI, Hidenori HINAGO, Masashi ISHIKAWA
    論文ID: 23-00037
    発行日: 2023年
    [早期公開] 公開日: 2023/05/12
    ジャーナル オープンアクセス 早期公開
    J-STAGE Data

    For lithium-sulfur (Li-S) batteries, high-concentration electrolyte that inhibits the dissolution of Li polysulfide has been widely studied; one such electrolyte contains sulfolane. This study investigates the conditions under which a microporous activated carbon cathode, derived from azurmic acid, operates stably in a sulfolane-based electrolyte. We expected this cathode to maintain a stable capacity in a sulfolane-based electrolyte because its micropores stabilize the S species. However, Li-S batteries containing this cathode and electrolyte exhibit significant capacity decay during cycling. The cutoff voltage during charge-discharge cycling is varied to suppress the capacity decay. At a discharge voltage of 1.4 V or lower, the cycle life of the Li-S batteries is significantly reduced. Conversely, increasing the cutoff voltage during discharge suppresses the capacity decay of Li-S batteries. On the other hand, increasing the upper voltage limit during charging increases the reversible capacity. Thus, the operating voltage range is optimized. This study indicates that the voltage range of Li-S batteries should be carefully determined depending on the type of cathode material and electrolyte.

  • Atsushi SAKUDA
    論文ID: 23-00030
    発行日: 2023年
    [早期公開] 公開日: 2023/05/10
    ジャーナル オープンアクセス 早期公開

    Lithium/transition-metal polysulfide batteries are candidate materials for next-generation batteries with high energy densities. Transition metal polysulfides and lithium- or sodium-containing transition metal sulfides exhibit large reversible capacities based on multi-electron processes, owing to the redox reactions of S in addition to the transition metal. This comprehensive paper aims to address the idea, research, and development of transition metal polysulfide electrode active materials and summarizes the author’s views on the concept of transition metal polysulfide electrodes. Furthermore, the diversity of coordination structures and unique structural changes during charging and discharging will be discussed.

  • Kentaro YAMAMOTO
    論文ID: 23-00032
    発行日: 2023年
    [早期公開] 公開日: 2023/04/26
    ジャーナル オープンアクセス 早期公開

    Electrode reactions in electrochemical devices often consist of charge transfer at electrode/electrolyte interface and charge compensation in electrode active material. Therefore, to design electrochemical devices with high electrochemical performance, it is important to understand electronic structures of the electrode/electrolyte interface and electrode bulk during electrochemical reactions, and to design electrode materials to control them. In this paper, certain phenomena at the electrode/electrolyte interface and electrode bulk in lithium-ion batteries are clarified by using synchrotron radiation X-ray analyses. The information obtained from those X-ray analyses are applied to control the structure of the electrode/electrolyte interface and electrode bulk. Moreover, new cathode materials for all-solid-state fluoride-ion with high power and cyclic performances have been developed, compared to simple metal/metal fluoride materials, by using the findings obtained from the synchrotron radiation X-ray analyses.

  • Yoshitaka AOKI
    論文ID: 23-00026
    発行日: 2023年
    [早期公開] 公開日: 2023/03/25
    ジャーナル オープンアクセス 早期公開

    In this paper, we describe new strategies to reduce the resistances related to cathode reactions and interfacial proton transfer in protonic solid oxide fuel cells (H+-SOFCs) based on proton-conducting BaZrxCe0.8−xM0.2O3−δ (M = Y, Yb, Sc etc.) by means of material and cell-structure design changes. First, an extension of the effective cathode reaction areas by employing the H+/O2−/e triple-conducting cathode is described. Cubic La0.7Sr0.3Mn1−xNixO3−δ (x = 0–0.3) can be hydrated under fuel cell conditions due to its large hydration enthalpy (∼100 kJ mol−1), whereas rhombohedral La0.7Sr0.3Mn1−xNixO3−δ does not exhibit hydration capabilities; hence, the porous anode cermet support fuel cells (PAFCs), which use the former as a cathode, possess significantly smaller cathode polarization resistances than the PAFCs that use the latter. Second, we describe a new thermodynamic mechanism for reducing the electrolyte and cathode reaction resistances in a hydrogen-permeable metal-support fuel cell (HMFC), which involves the blocking of the oxide ion minor conduction in the BaZrxCe0.8−xM0.2O3−δ electrolyte at metal/oxide heterointerfaces. The BaZrxCe0.8−xM0.2O3−δ membrane of HMFCs is forced to gain extra protons to compensate for the charge from the oxide ions accumulating near the heterointerfaces via blocking, resulting in extremely high proton conductivity. This promotes significant interfacial proton diffusion for cathode reactions.

  • Hazuki GOTO, Bungo OCHIAI, Yoshimasa MATSUMURA
    論文ID: 23-67008
    発行日: 2023年
    [早期公開] 公開日: 2023/02/17
    ジャーナル オープンアクセス 早期公開
    J-STAGE Data

    A reactive π-conjugated polymer, bromo-substituted polythiophene, was synthesized by constant potential electrooxidative polymerization of 3-bromo-4-dodecylthiophene in an acetonitrile solution of Bu4NPF6. The resulting polymer was applied as a reactive precursor for functional polythiophenes. The protonation via lithiation of the polybromothiophene proceeded quantitatively. The phenylation of the polybromothiophene by the Kumada-Tamao coupling reaction also proceeded with a 70 % efficiency. The changes in optical and electronic properties of the polymers by their reactions are discussed by the results of UV-vis absorption spectroscopy, photoluminescence spectroscopy, and cyclic voltammetric analysis. The emission colors of the bromo-substituted, protonated, and phenylated polymers were green, yellow, and blue, respectively, demonstrating the tunability of this approach.

  • Rumi IZUMIYA, Mahito ATOBE, Naoki SHIDA
    論文ID: 23-67010
    発行日: 2023年
    [早期公開] 公開日: 2023/02/16
    ジャーナル オープンアクセス 早期公開
    J-STAGE Data

    β-Scission from alkoxy radical enables selective Csp3-Csp3 bond cleavage under ambient conditions, offering a useful method for organic synthesis. Various photocatalytic systems for β-scission have been reported, where proton-coupled electron transfer (PCET) mechanism plays a key role in the generation of alkoxy radical and thus β-scission. Electrochemical β-scission has been mainly pioneered in the presence of mediator, and a direct electrochemical system has rarely been investigated. Here, we investigated the β-scission via direct electrochemical oxidation using a model compound with β-O-4 linkage. Synthetic experiments suggested smooth progress of β-scission in the presence of collidine as a base. Cyclic voltammetry measurement, voltammetric simulation, and quantum simulation suggested the PCET mechanism is responsible for the electrochemical reaction, which is followed by β-scission process. This report provides fundamental insights into the electrochemical β-scission via direct electron transfer on the electrode, which contribute to future applications such as biomass valorization.

  • Shohei YOSHINAGA, Mahito ATOBE, Naoki SHIDA
    論文ID: 23-67013
    発行日: 2023年
    [早期公開] 公開日: 2023/02/15
    ジャーナル オープンアクセス 早期公開

    Redox behavior is a fundamental and fascinating feature of polycyclic aromatic hydrocarbons (PAHs). Cyclic voltammetry (CV) measurements are commonly performed to estimate the electronic structure of PAHs and to determine the stability of their oxidation and reduction states. However, the influences of electrolytes on electrochemically oxidized/reduced PAHs have rarely been discussed. In this note, we report voltammetric analyses of five PAHs (anthracene, 9,10-dimethylanthracene, phenanthrene, pyrene, and perylene) in Bu4NB(C6F5)4/CH2Cl2 and Bu4NTfO/CH2Cl2, respectively, to highlight how the electrolyte-coordination affects the oxidative voltammetric behavior of PAHs. In most cases, reversible voltammetric responses were obtained with Bu4NB(C6F5)4/CH2Cl2, suggesting that this electrolyte is enough weakly coordinating to investigate its intrinsic oxidation behavior. On the other hand, irreversible voltammetric responses were obtained with Bu4NTfO/CH2Cl2, indicating that the presence of a relatively coordinating anion, TfO, destabilizes the radical cation species and induces further chemical and electrochemical processes. This study provides hints for rational electrolyte design to properly understand the redox behavior of molecules and maximize the potential of functional molecules for applications related to redox chemistry.

feedback
Top