2026-05-26 東京大学
イオンの「硬さ・柔らかさ」の組み合わせで変わる電池反応の起こりやすさ
＜関連情報＞
- https://www.t.u-tokyo.ac.jp/press/pr2026-05-26-002
- https://www.nature.com/articles/s41557-026-02150-5
金属電極電位はイオン添加によって変化する Metal electrode potential diverges with ion additions
Qiu Zhang,Seongjae Ko,Taisei Sakata,Shin-ichi Nishimura,Norio Takenaka,Atsushi Kitada,Chunsheng Wang & Atsuo Yamada
Nature Chemistry Published:26 May 2026
DOI:https://doi.org/10.1038/s41557-026-02150-5
Abstract
The electrode redox potential, which varies substantially with the electrolyte, governs both the direction and thermodynamic driving force of electrochemical reactions. However, a comprehensive understanding and effective control of redox potential shifts remain unestablished. Here we report the pronounced effect of coordination-shell ions on the redox potential of metal electrodes. Cooperative interactions between the metal ion and surrounding anions and cations with large differences in hardness/softness amplify the redox potential shift, as corroborated by liquid Madelung potential. Specifically, in the Zn/Zn2+ system, the addition of soft anions paired with hard cations destabilizes the Zn2+ solution structure and upshifts the redox potential, whereas hard anions with soft cations stabilize the structure and induce a downshift. Following this principle, a potential gap exceeding 0.6 V was achieved—a remarkably large but reasonable value for a divalent system. This ion hardness/softness-based strategy also demonstrates practical benefits in Zn plating/stripping tests, where electrolytes with upshifted redox potentials enable an average Coulombic efficiency exceeding 99.9%.
