Polymeric ionic conductor networks enable stable cycling of high-voltage lithium metal batteries using solid-state poly-ether electrolytes

Integrating high-voltage oxide cathodes with solid electrolytes significantly advances energy storage devices. Although poly(1,3-dioxolane) (PDOL)-based solid-state electrolytes are easy to prepare and compatible with lithium anodes, they suffer from poor antioxidant properties without suitable organic additives or cross-linking polymers. Here, we report a scalable method incorporating 2,2,2-trifluoroethyl-methacrylate (TFEMA) monomer and lithium salt into a high-voltage LiCoO2 cathode. This process creates an ionic network among the electrode components through ultraviolet light and heat treatment. The coordination interactions between TFEMA and LiCoO2 ensure the uniform dispersion of the polymeric ionic conductor networks within the cathode. As an additional solid-state electrolyte, the poly-TFEMA layer provides sufficient Li+ transport pathways among active materials. Moreover, with a high electrochemical stability window (>5.0 V), the poly-TFEMA layer effectively prevents the oxidative decomposition of PDOL on the cathode surface, thus reducing interfacial degradation. The present approach is both facile and feasible for mass production, which extends the operating voltage of PDOL to 4.6 V and improves the capacity retention of LiCoO2|PDOL|Li cells to 80.62% after 100 cycles.