Ultrathin thiol-ene crosslinked polymeric electrolyte for solid-state and high-performance lithium metal batteries

Solid polymer electrolyte (SPE) is a potential material for the next-generation safe battery system. However, the inability of SPEs to maintain mechanical strength and ionic conductivity is a bottleneck in further research. Here, a poly(ether-thioether) electrolyte with a thiol-ene crosslinked network was prepared by in situ click polymerization and supported on an electro-spun polyimide (PI) mat to provide an ultrathin membrane (19 µm in thickness). Combining a thiol-ene crosslinked network and the reinforcement of the electro-spun PI mat, this SPE membrane obtains high storage modulus (135 MPa), high ionic conductivity (2.24 × 10−4 S cm−1), and wide electrochemical window (up to 4.0 V) at 60°C. In addition, the Li-Li symmetrical cell based on the as-prepared electrolyte demonstrates stable cycling performance during Li plating/stripping, lasting more than 800 h at 0.1 mA cm−2. Such LiFePO4/Li cells with an ultrathin thiol-ene network SPE membrane achieve over 250-cycle stability at 0.5 C and 60°C. This work develops a new ultrathin polymer electrolyte for stable solid-state and high-performance lithium metal batteries.