Ultrastable Anode Interface Achieved by Fluorinating Electrolytes for All-Solid-State Li Metal Batteries

All-solid-state Li metal batteries (ASSLMBs) have attracted significant attention because of their high energy density and improved safety. However, the poor stability at the Li anode/solid-state electrolyte (SSE) interface is a long-standing problem that limits the current density and capacity, thus hindering the practical application of ASSLMBs. Herein, fluorination of an Argyrodite Li₆PS₅Cl (LPSCl) sulfide electrolyte is proposed to enhance the interfacial stability toward the Li metal anode. Because of the condensed and highly fluorinated interface that forms in situ with a self-healing essence, the Li metal symmetric cell employing the fluorinated LPSCl SSE enables ultrastable Li plating/stripping over 250 h at a superhigh current density of 6.37 mA cm^–2 and a cutoff capacity of 5 mAh cm^–2. Furthermore, the Li metal treated by the fluorinated LPSCl SSE is demonstrated to deliver good durability and rate capability in full cells. Fluorinating sulfide electrolytes provides a new strategy for realizing high-performance ASSLMBs.