Charging-free electrochemical system for harvesting low-grade thermal energy

TLDR

Low‑grade heat is abundant in industrial processes and the environment, yet efficient and low‑cost utilization is essential for meeting energy and environmental challenges. The study proposes using a rechargeable electrochemical cell whose voltage varies with temperature to harvest low‑grade thermal energy. By carefully tuning electrode composition, the cell can be charged solely by thermal energy, eliminating the need for external electricity. The system achieves a 2.0 % heat‑to‑electricity conversion efficiency between 20 °C and 60 °C and offers a charging‑free solution potentially useful for remote low‑grade heat harvesting.

Abstract

Significance Tremendous low-grade heat is stored in industrial processes and the environment. Efficient and low-cost utilization of the low-grade heat is critical to imminent energy and environmental challenges. Here, a rechargeable electrochemical cell (battery) is used to harvest such thermal energy because its voltage changes significantly with temperature. Moreover, by carefully tuning the composition of electrodes, the charging process is purely powered by thermal energy and no electricity is required to charge it. A high heat-to-electricity conversion efficiency of 2.0% can be reached when it is operated between 20 and 60 °C. Such charging-free characteristic may have potential application for harvesting low-grade heat from the environment, especially in remote areas.