Insights into the Thermopower of Thermally Regenerative Electrochemical Cycle for Low Grade Heat Harvesting
Chun Cheng, Sijia Wang, Peng Tan, Yawen Dai, Jie Yu, Rui Cheng, Shien‐Ping Feng, Meng Ni
Abstract
The thermally regenerative electrochemical cycle (TREC) is a promising technology for converting low-grade heat (<100 °C) to electrical power. In this work, the TREC with the NiHCF cathode and Zn anode achieves a markedly high thermopower (α) of −1.575 mV K–1 and a heat-to-electricity efficiency of 2.41% at the temperature difference of 30 °C (equivalent to 25.15% of Carnot efficiency), surpassing all the existing TREC systems. For the first time, the mixed membranes with mixed pH electrolytes are introduced in the TREC systems to boost α to a record-high value of −2.270 mV K–1. The proposed thermodynamic framework advances the understanding on the origin of α and electrochemical potential, which will guide people to engineer TRECs.