Anti-corrosion lithium anode interface by Li6.4La3Zr1.4Ta0.6O12 modified buffer layer for stable cycling of room-temperature solid-state lithium metal batteries.

Non-flammable butanedinitrile (SN) is recognized as a highly prospective plasticizer for significantly reducing the operating temperature of polyethylene oxide (PEO)-based solid polymer electrolytes. However, the instability of the lithium anode interface severely hinders the practical application of PEO/SN-based solid polymer electrolytes in room-temperature solid-state lithium metal batteries. In this work, we propose fast-ion conductive Li6.4La3Zr1.4Ta0.6O12 (LLZTO) nanoparticles as corrosion inhibitors to constructure a multifunctional buffer layer on the surface of PEO/SN-based solid electrolyte (PSE@LLZTO) to stabilize the interface structure of Li anode via a facile spin-coating transfer technique. This LLZTO modified buffer layer with rigid inorganic LLZTO phase and soft organic PEO-LiTFSI phase, not only significantly homogenizes lithium deposition, but also effectively improves the resistance to dendrite formation. Impressively, the LLZTO phase is able to adsorb free SN molecules, preventing them from continuously corroding the Li anode, thereby significantly reinforcing the interface stability. Meanwhile, these rigid LLZTO ceramic particles effectively inhibit lithium dendrite growth. Consequently, the Li symmetric cell demonstrates consistent performance for 1600 h at room temperature, and the LiFePO4|PSE@LLZTO|Li cells exhibit a high reversible specific capacity of 146 mA h g-1 with a remarkable capacity retention of 98.4 % after 200 cycles under 0.5C at room temperature. This study offers a feasible approach for the practical utilization of PEO/SN-based solid electrolyte systems in long lifespan solid-state lithium metal batteries.