Thermally depolymerizable polyether electrolytes for convenient and low-cost recycling of LiTFSI

Solid polymer electrolytes (SPEs) with LiTFSI (lithium bis(trifluoromethane sulfonimide)) are promising candidates for solid-state batteries, owing to their good interfacial contact with solid electrodes. Here, three copolymerized polyethers were prepared as SPEs, using the catalysts of SnF${}_2$ or SnF${}_2$-LiPF${}_6$. The thermal depolymerization of these polyethers was observed at elevated temperatures, which limits their operating temperature ranges. Once the catalyst is removed, the thermal degradation temperatures of these SPEs are raised by 30-55 °C, together with improved thermal performance in cells. For SPEs, the high price of LiTFSI is an obstacle for their large-scale application, and it's recycling is hindered by the strong interaction with polymers. By the thermal depolymerization of polyethers, LiTFSI can be easier reclaimed from above mentioned SPEs and even the commercial PEO(poly(ethylene-oxide)) based SPE in rates of 70-80 %, providing a low-cost strategy for the recycling of LiTFSI. (© 2022 Wiley‐VCH GmbH)