Inorganic/polymer hybrid layer stabilizing anode/electrolyte interfaces in solid-state Li metal batteries

Li1.5Al0.5Ge1.5(PO4)3 (LAGP) is a solid-state electrolyte with high ionic conductivity and air stability but poor chemical stability and high interfacial impedance when directly contacted with Li metal. In this work, we develop an inorganic/polymer hybrid interlayer composed of Li bis(trifluoromethylsulfonyl)imide/poly(vinylene carbonate) polymer electrolyte and SiO2 submicrospheres to stabilize the Li/LAGP interface. The polymeric component renders high ionic conductance and low interfacial resistance, whereas the inorganic component imparts flame retardancy and a physical barrier to the known Li-LAGP side reaction, together enabling stable Li stripping/plating for more than 1,500 h at room temperature. With this interlayer at both electrodes, all-solid-state Li∥LiFePO4 full cells with stable cycling performance are also demonstrated.