Dual Interface Compatibility Enabled via Composite Solid Electrolyte with High Transference Number for Long-Life All-Solid-State Lithium Metal Batteries.

The development of solid-state electrolytes (SSEs) effectively solves the safety problem derived from dendrite growth and volume change of lithium during cycling. In the meantime, the SSEs possess non-flammability compared to conventional organic liquid electrolytes. Replacing liquid electrolytes with SSEs to assemble all-solid-state lithium metal batteries (ASSLMBs) has garnered significant attention as a promising energy storage/conversion technology for the future. Herein, a composite solid electrolyte containing two inorganic components (Li 6.25 Al 0.25 La 3 Zr 2 O 12 , Al 2 O 3 ) and an organic polyvinylidene difluoride matrix is designed rationally. X-ray photoelectron spectroscopy and density functional theory calculation results demonstrate the synergistic effect among the components, which results in enhanced ionic conductivity, high lithium-ion transference number, extended electrochemical window, and outstanding dual interface compatibility. As a result, Li||Li symmetric battery maintains a stable cycle for over 2500 h. Moreover, all-solid-state lithium metal battery assembled with LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode delivers a high discharge capacity of 168 mAh g -1 after 360 cycles at 0.1 C at 25 °C, and all-solid-state lithium-sulfur battery also exhibits a high initial discharge capacity of 912 mAh g -1 at 0.1 C. This work demonstrates a long-life flexible composite solid electrolyte with excellent interface compatibility, providing an innovative way for the rational construction of next-generation high-energy-density ASSLMBs.