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Enthalpy-Entropy Compensation Governs the Solvent-Mixing Effect in Electrochemical Thermoelectric Conversion
Hongyao Zhou1, Nozomi Yoneda1,2, Kakeru Nohara1
1Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-0033, Japan.
Journal of the American Chemical Society
|January 20, 2026
Summary
Enthalpy-entropy compensation explains how solvent mixing enhances thermocell performance. This principle allows for designing high-performance organic thermocells by predicting molecular properties.
Area of Science:
- Electrochemistry
- Materials Science
- Chemical Engineering
Background:
- Thermocells generate electricity from temperature gradients via redox reactions.
- Performance depends on the temperature coefficient of electrochemical potential (α).
- Solvent mixing is known to improve α, but the mechanism is unclear.
Purpose of the Study:
- To elucidate the mechanism of solvent-mixing effects in thermocells.
- To establish a general framework for modeling these effects.
- To guide the molecular design of high-performance thermocells.
Main Methods:
- Variable-temperature electrochemistry to study methanol-quinone dianion interactions in acetonitrile.
- Density Functional Theory (DFT) for screening molecular properties.
- Analysis of enthalpy-entropy compensation.
Main Results:
- Demonstrated enthalpy-entropy compensation as a model for solvent-mixing effects.
- Identified a linear relationship between hydrogen-bond entropy (ΔSHB) and enthalpy (ΔHHB).
- Achieved the highest α value (-3.1 mV K⁻¹) in liquid organic thermocells using tetramethyl-para-benzoquinone.
Conclusions:
- Enthalpy-entropy compensation provides a predictive framework for thermocell solvent design.
- This principle enables the rational design of organic molecules for high-performance thermocells.
- The findings offer a general strategy for enhancing thermocell efficiency.
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