温度差から電気を生み出す分子の設計に新たな指針～電解液中の水素結合の「強さ」と「乱雑さ」が相関することを証明～

2026-01-21 東京大学

熱電変換に用いられる電解液中で形成される水素結合の強さと乱雑さは相関する

＜関連情報＞

• https://www.s.u-tokyo.ac.jp/ja/press/11047/
• https://pubs.acs.org/doi/10.1021/jacs.5c14655

電気化学的熱電変換における溶媒混合効果はエンタルピー・エントロピー補償によって制御される Enthalpy–Entropy Compensation Governs the Solvent-Mixing Effect in Electrochemical Thermoelectric Conversion

Hongyao Zhou,Nozomi Yoneda,Kakeru Nohara,Nathan Hartanto,Yusuke Wakayama,Hirotaka Inoue,Hideo Ando,Kazuhiko Matsumoto,and Teppei Yamada
Journal of the American Chemical Society  Published: January 20, 2026
DOI:https://doi.org/10.1021/jacs.5c14655

Abstract

Thermocells convert temperature gradients into electrical energy using the entropy change of a redox reaction. The performance of thermocells is governed by the temperature coefficient of electrochemical potential (α), and various strategies are reported to increase α. Solvent mixing has been recognized as one of the effective methods; however, the underlying mechanism remains elusive due to the absence of either systematic experimental or reliable theoretical validation. Herein, we demonstrate that enthalpy–entropy compensation provides a general framework for modeling solvent-mixing effects in thermocells. Variable-temperature electrochemistry reveals the linear relationship between hydrogen-bond entropy (ΔS_HB) and enthalpy (ΔH_HB) arising from the interactions between methanol and quinone dianions in acetonitrile. This enthalpy–entropy compensation principle enables the prediction of quinone derivatives with a large entropy change─and consequently a large α value─through DFT-based screening of ΔH_HB. Notably, tetramethyl-para-benzoquinone exhibits an α value of −3.1 mV K^–1, which is the highest absolute value in liquid-based all-organic thermocells. These findings show that enthalpy–entropy compensation is a general molecular design strategy for creating high-performance thermocells.