Thermally Driven Energy Conversion and Storage Based on Organic Nanocomposites
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Thermoelectric (TE) energy conversion is very effective in capturing low-grade waste heat to supply electricity particularly to small devices such as sensors, wireless communication units, and wearable electronics. Conventional inorganic thermoelectric materials, however, are often inadequately brittle, expensive, toxic, and heavy. I have developed both p- and n-type fabric-like flexible light-weight materials by functionalizing the carbon nanotube (CNT) mats. The poor thermopower and only ptype characteristics of typical CNTs have been converted into both p- and n-type with high thermopower. With the optimized device design to maximally utilize temperature gradients, an electrochromic glucose sensor was successfully operated without batteries or external power supplies, demonstrating self-powering capability. In addition to the development of high performance organic thermoelectric devices, I studied a novel method of simultaneously generating a large voltage from a temperature gradient and storing electrical energy by utilizing thermally-driven ion diffusion (Soret effect) mechanism. I have observed extremely high output voltage (8 mV/K) in an ionic conducting film, polystyrene sulfonic acid (PSSH), which was utilized as a driving force of electrochemical reactions in electrodes, resulting in a charging behavior without an external power supply. With a small temperature difference (5 K) possibly created over wearable energy harvesting devices, the thermally chargeable supercapacitor (TCSC) produced 38 mV with a large areal capacitance (1200 F/m^2).
Kim, Suk Lae (2017). Thermally Driven Energy Conversion and Storage Based on Organic Nanocomposites. Doctoral dissertation, Texas A & M University. Available electronically from