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.