Direct Thermal Charging Cell Using Nickel Hexacyanoferrate (ΙΙ) Anode for Green Recycling of Low-Grade Heat

Direct thermal charging cell (DTCC) converts heat to electricity by thermal charging and electrical discharging at high temperature and self-regeneration at low temperature. In this work, DTCC adopts recyclable NiHCFeII anode and environmentally friendly KCl electrolyte, realizing the green recycling via chemical treatment for electrodes after long-term operation. The newly designed DTCC achieves the heat-to-electricity conversion efficiency of 3.59% (26.2% of Carnot efficiency) at 70 °C, leaping to the forefront of existing thermoelectrochemical and thermoelectric systems in the low-grade heat regime. The developed system has the advantages of green technology, flexibility, cost-effectiveness, and scalability, making it promising in practical applications for direct energy conversion from low-grade heat sources.