Study on Stable Lithiophilic Ag Modification Layer on Copper Current Collector for High Coulombic-Efficiency Lithium Metal Anode

Abstract

High energy-density lithium metal batteries will be crucial in improving the driving range and promoting electric vehicles. The lithophilic modification layer is usually introduced to improve CE and cycle stability. However, the stability of the lithophilic modified layer in long-term cycling and lithophilic modification strategies for anode current collectors in all-solid-state anode-free lithium batteries are rarely investigated. Here, we prove the failure process of the silver lithophilic modified layer towards lithium metal anode through electrochemical cycling in liquid electrolytes. Combined with EIS, SEM, and XPS analysis, the failure is due to the formation of SEI on the Ag surface and the silver particles’ peeling off from the current collector during cycling, which forms “dead silver.” And we construct carbon-incorporated lithium phosphorous oxynitride (LiCPON) -based all-solid-state Li/Cu half-cells to evaluate the stability of the lithophilic Ag layer. The introduction of Ag between solid electrolyte (LiCPON) and current collector enables the long-term cycle (367th) of all-solid-state Li/Cu half cells with high CE. Our work clarifies the issue of Ag deactivation and provides a method for evaluating modified layers’ use and building stable electrolyte/anode interfaces in all-solid-state anode-free lithium batteries.