A flexible, robust, and high ion-conducting solid electrolyte membranes enabled by interpenetrated network structure for all-solid-state lithium metal battery

Poly(vinyl alcohol)/poly(ethylene glycol) (PVA/PEG) semi-interpenetrating networks (s-IPN) were synthesized for the application of solid electrolyte membranes of lithium metal batteries. Thermal, mechanical and dimensional stability, lithium-ion conductivity, interfacial compatibility, and cell performance were evaluated to assure their application. As this s-IPN structure suppressed the crystallinity by formation of network structure, both the lithium-ion conductivity and mechanical strength were simultaneously enhanced. The PVA/PEG-3s-IPN showed the highest lithium-ion conductivity of 3.26 × 10−4 S cm−1 in a wide electrochemical window (5.8 V vs. Li/Li+), maintaining the robust solid-state with the tensile strength beyond 16.2 MPa at room temperature. The synthesized solid electrolyte membranes exhibited quite high specific capacity over 122 mAh g−1 at 0.1 C from Li|PVA/PEG-3 s-IPN|LiFePO4 cell and the long-term stable lithium stripping/plating performance for 1000 cycles from Li symmetric cell.