Energy Density in Ionic Thermoelectric Generators by Prussian Blue Electrodes

Solid-state ionic thermoelectric generators have emerged as promising solutions for efficient harvesting of low-grade waste heat. However, the main challenge in achieving continuous power supply is the low efficiency of thermoelectric conversion. In this work, substantial achievements have been made in improving the thermoelectric conversion characteristics by introducing redox pairs on the electrode surfaces. This approach takes advantage of the synergistic effect of thermal diffusion and thermoelectric effects to maximize the conversion efficiency. To improve the thermoelectric storage and output power performance, Prussian blue was attached to a carbon woven fabric and used as an electrode. The incorporation of Prussian blue/carbon woven fabric electrodes results in an increase in current density output and an instantaneous power density of 3.7 mW/m²·K². Furthermore, under a temperature gradient of 10 K, the output energy density for 2 h is 194 J/m², and the Carnot relative efficiency is as high as 0.12% at a hot side temperature (T_H) of 30 ℃ and a cold side temperature (T_C) of 20 ℃. Our findings validate the efficacy of integrating thermal diffusion and redox reactions in ionic thermoelectric generators, paving the way for the progress of thermocharged devices and their potential commercial applications.