Construction and application of thermogalvanic hydrogels

Low-grade heat (below 373 Kelvins) is abundant and ubiquitous, yet the lack of cost-effective recovery technologies frequently impedes its effective utilization. The advent of thermogalvanic hydrogel thermocells has garnered significant attention due to their high thermopower, inherent flexibility, low cost, and scalability. Thermogalvanic hydrogels have significantly enhanced their thermoelectric performance, resulting in the development of functional materials that exhibit flexibility, stretchability, self-healing, and frost resistance. However, there are substantial challenges in developing multifunctional thermogalvanic hydrogels that combine high power density and efficiency with practical applicability. This review discusses the synthesis of the novel redox couple, improving the performance of electrolytes to increase thermopower, creating electrodes with extensive surface areas for better current density and flexibility, and optimizing thermocell structure design to improve performance further. This comprehensive review aims to propel progress toward higher performance levels and broader applications of thermogalvanic hydrogel thermocells.