Efficient Harvesting Waste Heat by Zn‐Ion Battery Under Thermally Regenerative Electrochemical Cycles

Abstract Typical technologies that can convert waste heat into electricity include thermoelectrics, thermionic capacitors, thermo‐cells, thermal charge cells, and thermally regenerative electrochemical cycles. They have small thermal‐to‐electrical conversion efficiency or poor stability, severely hindering the efficient recovery of waste heat. Herein, a thermally regenerative electrochemical Zn‐ion battery to work under Carnot‐like mode to efficiently harvest waste heat into electricity is successfully developed. Through introducing Layered Double Hydroxides to modify the battery's anode reaction, a record absolute high temperature coefficient of 2.944 mV K −1 is achieved in NiHCF/Zn battery, leading to a high thermal‐to‐electrical conversion efficiency of 26.08% of the Carnot efficiency and an extraordinary energy efficiency of 104.11% when the battery is charged at 50 °C and discharged at 5 °C. This work demonstrates that thermally regenerative electrochemical batteries can effectively harvest waste heat to provide a powerful energy conversion technology.