p-n Conversion of Thermogalvanic Cells by Harnessing the Micellization of Thermoresponsive Diblock Copolymers

Thermoelectric energy conversion based on the Seebeck effect holds great potential for effectively mitigating economic and environmental impacts. In contrast to conventional solid semiconductor thermoelectric cells, liquid thermogalvanic cells (TGC) have 1 order of magnitude higher thermopower of approx. 1 mV K-1. However, very limited redox pairs were reported to generate outstanding thermopowers for TGCs. Therefore, achieving n-p or p-n conversion for expanding redox couples is highly promising to resolve the challenge for TGCs. Herein, the pn conversion of the I-/I-3(-) TGC with high thermopowers was accomplished by employing easily prepared and scalable thermoresponsive diblock copolymers. By combining the distinct anionpolymer interaction and the micellization of the diblock copolymer, variable concentrations of ions invert the redox reactions at hot and cold sides. As a result, the efficient p-n conversion and enhanced power conversion efficiency was achieved for the I-/I-3(-) TGC with the introduction of copolymers. Building on the different ion-polymer interactions, the strategy developed in this work is also highly expected to extend to other electrochemical processes and applications.