Interface-Enabled Ion Conduction in Li₁₀GeP₂S₁₂–Poly(ethylene Oxide) Hybrid Electrolytes

Organic–inorganic hybrid solid electrolytes are expected to integrate the merits of both moieties for addressing the challenges in achieving fast ion conduction and high stability for energy storage applications. Li10GeP2S12 (LGPS)-poly(ethylene oxide) (PEO) (bis(trifluoromethane)sulfonimide lithium (LiTFSI)) hybrid electrolytes have been prepared, which exhibit ionic conductivities up to 0.22 mS cm–1 and good long-term cycling stability against Li-metal. High-resolution solid-state 6Li NMR is employed to examine the local structural environments of Li ions in the LGPS-PEO (LiTFSI) hybrids, which identifies Li ions from PEO (LiTFSI), in bulk LGPS, and at LGPS-PEO interfaces. Tracer-exchange Li NMR reveals that Li ions transport mainly through LGPS-PEO interfaces. The impact of LGPS and LiTFSI contents on the interface chemistry within LGPS-PEO hybrid electrolytes has been examined. The measured conductivities of LGPS-PEO hybrids positively correlate with the available Li ions at LGPS-PEO interfaces. This study provides insights for engineering interfaces in organic–inorganic hybrids to develop high-performance electrolytes for solid-state rechargeable batteries.