A Novel UV-Cured Semi-IPN Structure PEO@Nano-SiO2 Composite Polymer Electrolyte for Lithium Metal Batteries

Polymer electrolyte is an effective way to solve stability and security issues in lithium (Li) metal anode caused by nonuniform lithium deposition and unstable solid electrolyte interphase (SEI). However, it still remains a challenge to obtain an electrolyte that combines high ionic conductivity and mechanical properties. Herein, we used nano-SiO2 grafted with reactive groups as crosslinkers to cooperate with PEO to construct a composite polymer network. And this polymer network was further interpenetrated with PVDF-HFP to build a Semi-IPN gel composite polymer electrolyte (Semi-IPN-GCPE) by simple UV curing. The polymer electrolyte exhibited high ionic conductivity (2.71 × 10–3 S cm–1 at room temperature), wide electrochemical stable window (∼5 V vs. Li/Li+), considerable tensile strength (7.04 MPa), breaking strain (248.1%), good thermal stability up to 330 °C and excellent stability with lithium metal anode. The assembled Li/Semi-IPN-GCPE/LiFePO4 cell delivered specific capacities of 103 mAh g–1 at 10 C and presented above 90% capacity reten- tion after 300 cycles at 1 C. Our work provides a facile approach to preparing dendrite-suppressing polymer electrolytes with potential applicability in next-generation Li metal batteries.