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.