Lithium bis(oxalate)borate crosslinked polymer electrolytes for high-performance lithium batteries

Abstract Solid electrolytes play a vital role in solid-state Li secondary batteries, which are promising high-energy storage devices for new-generation electric vehicles. Nevertheless, obtaining a suitable solid electrolyte by a simple and residue-free preparation process, resulting in a stable interface between electrolyte and electrode, is still a great challenge for practical applications. Herein, we report a self-crosslinked polymer electrolyte (SCPE) for high-performance lithium batteries, prepared by a one-step method based on 3-methoxysilyl-terminated polypropylene glycol (SPPG, a liquid oligomer). It is worth noting that lithium bis(oxalate)borate (LiBOB) can react with SPPG to form a crosslinked structure via a curing reaction. This self-formed polymer electrolyte exhibits excellent properties, including high room-temperature ionic conductivity (2.6 × 10-4 S cm-1), wide electrochemical window (4.7 V), and high Li ion transference number (0.65). The excellent cycling stability (500 cycles, 83%) further highlights the improved interfacial stability after the in situ formation of SCPE on the electrode surface. Moreover, this self-formation strategy enhances the safety of the battery under mechanical deformation. Therefore, the present self-crosslinked polymer electrolyte shows great potential for applications in high-performance lithium batteries.