Wearable Thermocells Based on Gel Electrolytes for the Utilization of Body Heat

Abstract Converting body heat into electricity is a promising strategy for supplying power to wearable electronics. To avoid the limitations of traditional solid‐state thermoelectric materials, such as frangibility and complex fabrication processes, we fabricated two types of thermogalvanic gel electrolytes with positive and negative thermo‐electrochemical Seebeck coefficients, respectively, which correspond to the n‐type and p‐type elements of a conventional thermoelectric generator. Such gel electrolytes exhibit not only moderate thermoelectric performance but also good mechanical properties. Based on these electrolytes, a flexible and wearable thermocell was designed with an output voltage approaching 1 V by utilizing body heat. This work may offer a new train of thought for the development of self‐powered wearable systems by harvesting low‐grade body heat.