Improving thermal stability and kinetical properties through polymer brushes towards wide-temperature solid-state lithium metal batteries

Abstract

The operation of solid-state lithium metal batteries (SSLMBs) under wide temperature ranges have been considered as the final stage of commercialization of SSLMBs. However, hard Li-ion transport at low temperatures and inferior interfacial stability at high temperatures remains challenging issues. Herein, to solve both the aforementioned issues, we introduce copolymer brushes (PASLi-PEG) comprised of poly-(lithium 2-acrylamido-2-methylpropanesulfonic acid) and poly(ethylene glycol) diacrylate onto PE separators into the succinonitrile polymer electrolyte (SNPE). The designed PASLi-PEG brushes facilitate the formation of stable SEI layer, thereby enhancing the high-temperature stability of the resulting batteries. Moreover, the PASLi-PEG brushes offer fast and continuous Li-ion channels to overcome the high Li-ion transfer barrier. As a result, the resulting solid-state Li||LiFePO₄ battery exhibits a long cycling life of 1600 cycles at 60 °C and at 5 C. Notably, the Li||LiFePO₄ battery delivers high capacities of 124.9 mAh g⁻¹ at −15 °C as well as 108.4 mAh g⁻¹ at −20 °C and at the rate of 0.1 C. This strategy effectively enhances thermal stability and Li-ion transport kinetics at wide temperatures, which can be extended to other solid-state batteries under extreme conditions.