Thermo-electrochemical cells enable efficient and flexible power supplies: From materials to applications

Low-grade waste heat recovery is a promising pathway to achieving the goal of carbon neutrality. In recent years, thermo-electrochemical cells (also known as thermocells or thermogalvanic cells) driven by low-grade heat have been emerging as a cutting-edge technology due to their ultrahigh Seebeck coefficient, high flexibility and low cost, and they possess large application prospects in wearable electronic devices, self-powered Internet-of-Thing sensors and industrial waste heat recovery. In the past years, a large deal of work has been conducted to improve the power density and conversion efficiency from the aspects of electrode materials, electrolyte materials, etc., and giant advances have been achieved. However, the commercial applications of thermocells are still hindered by their low power density and conversion efficiency. Given these issues, this work aims to give an overview of the fundamentals, materials, operating parameters, research methods, current applications and specify the corresponding underlying challenges, and conclude the prospects to provide valuable guidelines for further design and optimization of thermocells.