Books 【 display / non-display 】

Books 【 display / non-display 】

• Next Generation Batteries -Realization of High Energy Density Rechargeable Batteries-

  Kiyoshi Kanamura（編集）, Kazujde Ueno (Part： Contributor , Range: Fundamental Properties and Solubility Toward Cathode Active Materials )

  Springer Singapore  2021.03 ISBN: 978-981-336-667-1

• Ionic liquid devices, chapter 14 design and new energy application of ionic liquids

  Shiro Seki, Shimpei Ono, Nobuyuki Serizawa, Yasuhiro Umebayashi, Seiji Tsuzuki, Kazuhide Ueno and Masayoshi Watanabe (Part： Joint Work )

  Royal Society of Chemistry  2017.09 ISBN: 9781788011815

• Frontier of Ionic Liquid Research Toward Practical Use

  (Part： Contributor )

  2016.12 ISBN: 9784781312279

  Amazon

• Electrochemical Aspects of Ionic Liquids 2nd edition, Chapter 2 Physical chemistry of ionic liquids, inorganic and organic, protic and aprotic

  C. Austen Angell, Xu Wu, Masahiro Yoshizawa, Akitoshi Hayashi, Jean-Philippe Belieres, Pierre Lucas, Marcelo Videa, Zuofeng Zhao, Kazuhide Ueno, Younes Ansari, Jeffery Thomson, Dominic Gervasio (Part： Contributor )

  John Wiley & Sons, Inc.  2010.03

• Ionic Liquid III-Challenges to Nano-Bio Sciences-

  (Part： Contributor )

  2010.01 ISBN: 9784781302027

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Papers 【 display / non-display 】

Papers 【 display / non-display 】

• Highly Concentrated NaN(SO₂F)₂/3-Methylsulfolane Electrolyte Solution Showing High Na-Ion Transference Number under Anion-Blocking Conditions

  TATARA Ryoichi, OKAMOTO Yukihiro, UGATA Yosuke, UENO Kazuhide, WATANABE Masayoshi, DOKKO Kaoru

  Electrochemistry ( 公益社団法人　電気化学会 )    2021.09  [Refereed]

  Joint Work

  　View Summary

  <p>The performance of a sodium-ion (Na) battery is significantly influenced by its electrolyte characteristics. In particular, the transport properties of the electrolyte have considerable effects on the discharge rate capability. During discharging of a Na battery at high current densities, a concentration gradient of Na salt develops because both cations and anions are mobile in the liquid electrolyte. Concentration polarization can be suppressed by increasing the Na⁺ transference number (<i>t</i>_Na+) of the electrolyte. This study demonstrates that highly concentrated NaN(SO₂F)₂ dissolved in 3-methylsulfolane (MSL) exhibits a high <i>t</i>_Na+ value of >0.6 under anion-blocking conditions. Raman spectroscopy revealed that Na⁺ ions formed complexes with MSL and anions in the electrolyte. Na⁺ ions exchange ligands dynamically and move faster than the ligands, resulting in a high <i>t</i>_Na+. The high <i>t</i>_Na+ enables a high-rate discharge of the Na battery, despite the low ionic conductivity of the highly concentrated electrolyte.</p>

  DOI CiNii

• Design of Polymer Network and Li+ Solvation Enables Thermally and Oxidatively Stable, Mechanically Reliable, and Highly Conductive Polymer Gel Electrolyte for Lithium Batteries

  Kei Hashimoto, Ryoichi Tatara, Kazuhide Ueno, Kaoru Dokko, Masayoshi Watanabe

  Journal of The Electrochemical Society   168 ( 9 )   2021.09  [Refereed]

  Joint Work

  DOI

• Solvate electrolytes for Li and Na batteries: structures, transport properties, and electrochemistry

  Yosuke Ugata, Keisuke Shigenobu, Ryoichi Tatara, Kazuhide Ueno, Masayoshi Watanabe, Kaoru Dokko

  Physical chemistry chemical physics     2021.09  [Refereed]

  Single Work

  DOI

• Electrochemical Properties of Poly(vinylidene fluoride-<i>co</i>-hexafluoropropylene) Gel Electrolytes with High-Concentration Li Salt/Sulfolane for Lithium Batteries

  OCK Ji-young, FUJISHIRO Miki, UENO Kazuhide, WATANABE Masayoshi, DOKKO Kaoru

  Electrochemistry ( 公益社団法人　電気化学会 )    2021.08  [Refereed]

  Joint Work

  　View Summary

  <p>Combining highly concentrated electrolytes with a polymer network is a valid approach to simultaneously achieve fast Li⁺ ion transport, high thermal stability, and a wide electrochemical window in a quasi-solid-state form. In this work, flexible gel electrolytes comprising commercially available poly(vinylidene fluoride-<i>co</i>-hexafluoropropylene) (PVDF–HFP) and highly concentrated electrolytes of Li salts/sulfolane (SL) were prepared by a simple solution casting method. The anionic effects of the gel electrolytes on the Li-ion conductivity and charge transfer kinetics at the gel/electrode interface were investigated. The SL-based gel electrolyte with lithium bis(fluorosulfonyl)amide (LiFSA) showed an ionic conductivity of 0.7 mS cm⁻¹ and a high Li transference number (>0.5) at 30 °C. The charge transfer resistance in a [Li/gel/LiCoO₂] cell with LiFSA was lower than that of the cells with lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) or LiBF₄, indicating faster interfacial charge transfer kinetics in the gel electrolyte with FSA. The Li/LiCoO₂ cell with the LiFSA/SL gel electrolyte exhibited a higher capacity than that of the cells with the LiTFSA/SL and LiBF₄/SL gel electrolytes. Hence, rationally designed gel electrolytes containing highly concentrated SL-based electrolytes enable the high rate performance of Li batteries.</p>

  DOI CiNii

• Rate Performance of LiCoO₂ Half-cells Using Highly Concentrated Lithium Bis(fluorosulfonyl)amide Electrolytes and Their Relevance to Transport Properties

  KONDOU Shinji, DOKKO Kaoru, WATANABE Masayoshi, UENO Kazuhide

  Electrochemistry ( 公益社団法人　電気化学会 )  89 ( 4 )   389 - 394   2021.07  [Refereed]

  Joint Work

  　View Summary

  <p>For the rapid charge-discharge performance of Li-ion batteries (LIBs), ionic conductivity (<i>σ</i>) and Li ion transference number (<i>t</i>₊) are important parameters of electrolytes. Electrolytes with high <i>t</i>₊ alleviate the concentration polarization upon fast charge-discharge, and prevent the diffusion-limited mass transfer of Li⁺ ions. Recent studies have suggested that certain highly concentrated electrolytes exhibit better rate performances than conventional organic electrolytes despite their lower <i>σ</i>. However, the relationship between the transport properties (<i>t</i>₊ and <i>σ</i>) of highly concentrated electrolytes and the enhanced rate performance of LIBs is yet to be elucidated. To evaluate the rate performance of LIBs with highly concentrated electrolytes in terms of transport properties, we investigated the discharge rate capability of LiCoO₂ (LCO) half-cells using highly concentrated lithium bis(fluorosulfonyl)amide (Li[FSA]) electrolyte in γ-butyrolactone (GBL), acetonitrile (AN), dimethyl carbonate (DMC), and 1,2-dimethoxyethane (DME) solvents. There was a remarkable solvent dependence of <i>t</i>₊, and the highest <i>t</i>_Li⁺^current of 0.67 was observed for GBL-based electrolyte measured using the very-low-frequency impedance spectroscopy (VLF–IS) method. The LCO half-cell with GBL-based electrolyte delivered higher discharge capacities than the cells with DMC- and DME-based electrolytes at high current densities. The improved rate performance in GBL-based electrolytes was attributable to enhanced Li⁺ ion mass transfer derived from the high <i>t</i>_Li⁺^current. We demonstrated the importance of <i>t</i>_Li⁺^current on the rate capability of LCO half-cells with highly concentrated electrolytes for high-rate battery performance.</p>

  DOI CiNii

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Review Papers 【 display / non-display 】

Review Papers 【 display / non-display 】

• Electrochromic Gels That Change Their Structural Colors

  UENO Kazuhide,WATANABE Masayoshi

  Journal of Polymer Science ( The Society of Polymer Science, Japan )  55 ( 12 ) 934 - 937   2006.12  [Refereed]  [Invited]

  Introduction and explanation (scientific journal)   Joint Work

  DOI CiNii