Enhancing heat-to-electricity conversion performance of the thermally regenerative electrochemical cycle using carbon-copper composite electrodes

Abstract

Low-grade heat is ubiquitous but difficult to be recovered. Thermally regenerative electrochemical cycle (TREC) system is expected to be one of the technologies for efficient recovery of low-grade heat. However, due to the limited temperature coefficient and temperature difference, it is difficult to further improve the heat-to-electricity conversion performance of TREC system. Therefore, a TREC system with carbon-copper composite negative electrode is proposed. By studying various factors (acid treatment, current density, and electrolyte concentration) for the deposition of copper metal on carbon cloth, suitable conditions for the preparation of carbon-copper composite electrodes were determined. The proposed method increased the electrode reaction contact area, reduced the electrical energy charged during the TREC system cycle, and increased the heat-to-electricity conversion efficiency of the system to 1.3 times (from 2.97% to 3.86%) compared with the conventional system with copper sheet negative electrode.