Thermally-induced ion transport has been recently reported to exhibit extremely large thermally induced voltage in contrast to conventional thermoelectrics mainly utilizing thermally-driven electron transport. Here comparative experimental studies about the thermoelectric behaviors of different types of solid-state ionic conductors have been carried out. Their thermopower values have been found to be on the order of 1~10 mV/K. Based on the transport studies, novel methods for generating a large voltage from a temperature gradient and simultaneously storing electrical energy have been developed without losing the benefit of solid-state no-moving part devices like conventional thermoelectrics. Arrays of thermally chargeable supercapacitors have been batch-fabricated, and connected together to linearly raise the output voltage up to 2.1 V, suggesting excellent suitability for roll-to-roll mass manufacturing and practical implementation of thermal energy harvesting. The outcomes suggest that it may be feasible to eliminate needs for battery replacement and wired connections to power lines for various distributed electronic systems whenever and wherever a temperature gradient is present.
