Gel-based thermocells for low-grade heat harvesting

Thermocell, as a novel thermoelectric conversion device based on redox reaction or ion diffusion, has exhibited great advantages like high thermopower coefficient, cost effectiveness and good scalability for low-grade heat harvesting. Compared to the liquid-based thermocell, the gel-based version has garnered more and more attention because of its merits in leakage prevention, flexibility and integration, and significant achievements have been made in recent years. In this perspective, we briefly summarize the state-of-the-art progress on the gel-based thermocells. The basic working principle of thermocells is firstly introduced, followed by the discussion on the nuts and bolts for further system optimization. The emerging strategies on the performance improvement are highlighted as well as the underlying physics. Finally, the challenges and future directions in this field are prospected. Copyright (C) 2021 EPLA