Li-ion batteries (LIBs) have revolutionized the portable electronics industry and are transforming our transportation by electrifying vehicles. As one of the most important components in a LIB, the electrolyte is key to LIB's power performance, durability, and safety. Despite liquid electrolytes being mostly used in LIBs, in recent years solid electrolytes (SEs) emerge as promising due to their intrinsic non-flammability and better thermodynamic stability . The ion transport property of SEs, characterized by ionic conductivity or diffusivity, is one of the most important features of SEs because it governs the power performance and energy efficiency of solid-state LIBs. Another important property of SEs is their electrochemical stability window, which determines the voltage, therefore power and energy density of LIBs.