LAUSR

Thermocells convert waste heat to electricity without any pollution; however, the high cost and the corrosivity of redox species hinder their commercialization. In this work, we report the first demonstration of a thermocell that utilize abundant polysulfide as redox species. 1-Butyl-1-methylpyrrolidinium polysulfide (P14S3) is synthesized and the redox species are prepared by the addition of sulfur to the P14S3 solution in DMSO. In thermoelectric measurement, the sign of the Seebeck coefficient changes from -0.68 to +0.5 mV/K by the addition of sulfur in the cell. Operando UV-vis spectroscopy, as well as open circuit voltage analysis revealed that the change in the sign is attributed to the change in the dominating redox reactions by the addition of sulfur. This result also provides a thermodynamic aspect on polysulfides electrochemistry, which is of high importance in lithium-sulfur battery.