Redox Targeting‐Based Thermally Regenerative Electrochemical Cycle Flow Cell for Enhanced Low‐Grade Heat Harnessing
Hang Zhang, Feifei Zhang, Juezhi Yu, Mingyue Zhou, Wei Luo, Yann Mei Lee, Mayan Si, Qing Wang
Abstract
Abstract A large amount of low‐grade heat (<100 °C) is produced in electrical devices and mostly wasted. This type of heat without effective dissipation also causes compromised device performance, reliability, and lifespan. To tackle these issues, a redox targeting (RT)‐based flow cell with judiciously designed thermoelectrically active redox materials is demonstrated for the first time for efficient heat‐to‐electricity conversion through a thermally regenerative electrochemical cycle (TREC). Compared with the conventional TREC systems, the RT‐based flow cell not only reveals considerably enhanced thermoelectric efficiency, but the flow of redox fluids also provides a cooling function to the system. In this work, solid material Ni 0.2 Co 0.8 (OH) 2 and redox mediator [Fe(CN) 6 ] 4−/3− , both of which have negative temperature coefficient and share identical redox potential, are paired via RT‐reactions to boost the capacity and meanwhile thermoelectric efficiency of a [Fe(CN) 6 ] 4−/3− /Zn 0/2+ ‐based flow cell. Upon operating over the TREC cycle, the RT‐based flow cell converts heat to electricity at an unprecedented absolute thermoelectric efficiency of 3.61% in the temperature range of 25–55 °C.