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Vol. 18 (2026)

High-Performance Cu-Based Liquid Thermocells Enabled by Thermosensitive Crystallization and Etched Carbon Cloth Electrode

https://doi.org/10.1007/s40820-025-01977-w
Wei Fang
MOE Key Laboratory of Low‑Grade Energy Utilization Technologies and Systems, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People’s Republic of China
Zeping Ou
MOE Key Laboratory of Low‑Grade Energy Utilization Technologies and Systems, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People’s Republic of China
Yifan Wang
MOE Key Laboratory of Low‑Grade Energy Utilization Technologies and Systems, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People’s Republic of China
Zhe Li
MOE Key Laboratory of Low‑Grade Energy Utilization Technologies and Systems, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People’s Republic of China
Qian Huang
MOE Key Laboratory of Low‑Grade Energy Utilization Technologies and Systems, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People’s Republic of China
Pengchi Zhang
MOE Key Laboratory of Low‑Grade Energy Utilization Technologies and Systems, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People’s Republic of China
Xinzhe Li
MOE Key Laboratory of Low‑Grade Energy Utilization Technologies and Systems, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People’s Republic of China
Yujie Zheng
MOE Key Laboratory of Low‑Grade Energy Utilization Technologies and Systems, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People’s Republic of China
Lijun Hu
Hunan Key Laboratory for the Design and Application of Actinide Complexes, School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, Hunan, People’s Republic of China
Chen Li
MOE Key Laboratory of Low‑Grade Energy Utilization Technologies and Systems, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People’s Republic of China
Jianyong Ouyang
Department of Materials Science and Engineering, National University of Singapore, Singapore 117574, Singapore
Kuan Sun
MOE Key Laboratory of Low‑Grade Energy Utilization Technologies and Systems, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People’s Republic of China

Corresponding Author: Kuan Sun

kuan.sun@cqu.edu.cn

Nano-Micro Letters, Vol. 18 (2026), Article Number: 131

Abstract

Thermocells are garnering increasing attention as a promising thermoelectric technology for harvesting low-grade heat. However, their performance is often limited by the scarcity of high-performance redox couples that possess both high thermopower and rapid redox kinetics. This work addresses this challenge by leveraging our recently developed copper (I/II) (Cu+/Cu2+) redox couple. We significantly enhance the performance of Cu-based liquid thermocells by integrating a thermosensitive crystallization process with etched carbon cloth electrodes, achieving synergistic improvements in thermodynamic and kinetic performance. The thermosensitive crystallization process establishes a persistent Cu2+ concentration gradient, boosting the thermopower from 1.47 to 2.93 mV K−1. Moreover, the etched carbon cloth electrodes provide a larger electroactive surface area and demonstrate a higher current density. Consequently, the optimized Cu+/Cu2+ system achieved an exceptional normalized power density Pmax (ΔT)−2 of 3.97 mW m‒2 K−2. A thermocell module comprised of 20 cells directly power various electronic devices at a temperature difference of 40 K. This work successfully exhibits potential of Cu+/Cu2+ redox couple in thermoelectric conversion and introduces a valuable redox couple for high-performance thermocells.


Highlights:
1 A novel Cu+/Cu2+ redox couple was introduced to enable a thermosensitive crystallization process, significantly enhancing thermopower from 1.47 to 2.93 mV K‒1.
2 A readily fabricated etched carbon cloth electrode offered an enlarged electroactive surface area, demonstrating superior current density through improved kinetics.
3 The optimized Cu+/Cu2+ system, achieved through synergistic enhancements in thermodynamic and kinetic performance, delivered an outstanding normalized power density Pmax (ΔT)‒2 of 3.97 mW m‒2 K‒2.

Keywords

Thermocell Thermosensitive crystallization Porous carbon electrode Power density Low-grade heat harvest
Fang, Wei, Zeping Ou, Yifan Wang, Zhe Li, Qian Huang, Pengchi Zhang, Xinzhe Li, Yujie Zheng, Lijun Hu, Chen Li, Jianyong Ouyang, and Kuan Sun. 2026. “High-Performance Cu-Based Liquid Thermocells Enabled by Thermosensitive Crystallization and Etched Carbon Cloth Electrode”. Nano-Micro Letters 18 (January):131. https://doi.org/10.1007/s40820-025-01977-w.
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