Fig. 3. Schematic illustration of surface pretreatment using liquid-phase pathways.

(A) Surface processing strategies via various solution casting methods, including slurry casting, immersion, dripping, and spray casting. (B) High-polarity DMSO was selected to dissolve sufficient metal fluorides (e.g., SnF₂, InF₃, and ZnF₂), which is crucial to forming the uniform and robust BSLs on Li metal. (C) Design of a polymer-inorganic SEI using the RPC precursor rather than the electrolyte to trigger a chemical reaction with Li. (D) Potentiostatic stripping and galvanostatic plating for polishing of and formation of SEI on metal anode (MA) surface. (E) Ex situ SEI construction on the Li plate by electrochemical methods in 1.0 M LiTFSI-DOL/DME electrolyte with 0.02 M Li₂S₅–5.0 wt % LiNO₃ hybrid additives.