Multifunctional Interface for High-Rate and Long-Durable Garnet-Type Solid Electrolyte in Lithium Metal Batteries

Lithium dendrite growth in solid electrolytes is one of the major obstacles to the commercialization of solid-state batteries based on garnet-type solid electrolytes. Herein, we propose a strategy that can simultaneously resolve both the interface and electronic conductivity issues via a simple one-step procedure that provides multilayer protection at low temperature. We take advantage of the facile chemical conversion reaction, showing the wet-coated SnF₂ particles on the solid electrolyte effectively produces a multifunctional interface composed of LiF and Li–Sn alloy upon contact with lithium. We demonstrate the multifunctional interface enables the remarkably high critical current density up to 2.4 mA cm^–2 at 25 °C and the stable galvanostatic cycling for over 1000 h at 0.5 mA cm^–2 in the lithium symmetric cell. Moreover, the full cell delivers a robust cycle life of more than 600 cycles at 1.0 mA cm^–2, which is the highest performance at room temperature reported to date.