Selectively Wetted Rigid-Flexible Coupling Polymer Electrolyte Enabling Superior Stability and Compatibility of High-Voltage Lithium Metal Batteries

Solid polymer electrolytes (SPEs) are considered to be the key to solve the safety hazards and cycling performance of liquid high-voltage lithium metal batteries (HVLMBs), but still suffer from low conductivity and poor interfacial compatibility. Here, polyvinylidene fluoride-polyvinyl acetate-based (PVDF-PVAC) rigid-flexible coupling SPE selectively wetted by a tetramethylene sulfone (TMS) is prepared for high-performance and superior-safety HVLMBs. The intermolecular interactions in such SPE significantly facilitate lithium-ion conductivity and electrolyte/electrode interface wettability. Moreover, PVAC selectively wetted with the TMS enhances interface compatibility with Li anodes and high-voltage LiCoO2 cathodes. As a result, the as-assembled LiCoO2/lithium-metal solid-state batteries present excellent cyclability with 85% capacity retention after 200 cycles between 3.0 and 4.5 V at room temperature. Furthermore, pouch cells with the as-prepared SPE exhibit brilliant safety and superior interfacial compatibility. This study offers a promising and general selectively wetted design strategy to handle the compatibility and safety issues in HVLMBs.