Insights into the Thermopower of Thermally Regenerative Electrochemical Cycle for Low Grade Heat Harvesting

The thermally regenerative electrochemical cycle (TREC) is a promising technology for converting low-grade heat (<100 degrees C) to electrical power. In this work, the TREC with the NiHCF cathode and Zn anode achieves a markedly high thermopower (alpha) of -1.575 mV K-1 and a heat-to-electricity efficiency of 2.41% at the temperature difference of 30 degrees 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 a to a record-high value of -2.270 mV K-1. The proposed thermodynamic framework advances the understanding on the origin of alpha and electrochemical potential, which will guide people to engineer TRECs.

Automated summary

Thermally regenerative electrochemical cycle (TREC) technology converts low-grade heat into electrical power using NiHCF cathode and Zn anode. By introducing mixed membranes and mixed pH electrolytes, the thermopower of the system was effectively improved. This work advances the understanding and design of TREC systems.