Thermally Regenerative Electrochemical Cycle for Low-Grade Heat Harvesting

Tremendous low-grade heat (i.e., <130 °C) exists in solar thermal, geothermal, and industrial waste heat. Efficient conversion of low-grade heat to electricity can recover these wasted resources and reduce energy consumption and carbon footprint. Along with thermoelectrics and thermogalvanic cells, thermally regenerative electrochemical cycle (TREC) has attracted wide attention recently, because it has a high temperature coefficient (>1 mV/K), high efficiency, and low cost. In TREC, conversion to electricity is realized by charging–discharging an electrochemical cell at different temperatures. In this Perspective, we will discuss the principle of TREC and recent progress, such as new material systems and mechanisms. More importantly, we will give our opinions on the challenges and future directions of this field, including fundamental understanding, material design, and system engineering.