Melt-Infusion-Induced Electrolyte Surface Coating Stabilized Sulfide-Based All-Solid-State Lithium Metal Batteries

Sulfide-based all-solid-state lithium metal batteries (ASSLBs) are a potentially safe and high-energy electrochemical storage technology. The continuous interfacial degradation within sulfide solid-state electrolytes (SSEs) and Li metal however hinders Li⁺ transport and induces inhomogeneous Li deposition. Herein, we propose a melt-infusion method to introduce lithium trifluorosulfonylimide (LiTFSI) on Li_5.5PS_4.5Cl_1.5 (LPSCl) particles as an artificial coating. This artificial coating can mitigate interfacial side reactions and induce the generation of the LiF/Li₃N-rich solid electrolyte interphase (SEI). The combined experimental and theoretical results reveal that this LiF/Li₃N-rich SEI has the merits of accelerating Li⁺ transport and suppressing Li dendrites. It enables the Li anode to reach a high critical current density (CCD) up to 3.1 mA cm^–2. In conjunction with coated sulfide SSEs, Li-symmetric cells operate stably for 900 h at 2 mA cm^–2. The ASSLBs using this coated sulfide SSEs can reversibly charge/discharge at 2C over 1000 cycles with a 90.2% capacity retention. A high LiCoO₂ loading of 28.5 mg cm^–2 is further demonstrated in this ASSLB with cycling stability over 100 cycles at 0.2C.