Solvation Structure Engineering via Inorganic–Organic Composite Layer for Corrosion‐Resistant Lithium Metal Anodes in High‐Concentration Electrolyte

Abstract High‐concentration electrolytes have been reported to form an anion‐derived, inorganic‐rich solid electrolyte interphase on lithium metal electrodes; however, these electrodes suffer from high Li corrosion by the coordinated anions and consequent anion depletion. Herein, the study reports a composite layer comprising single‐ion conducting ceramic (SICC) nanoparticles and a gel polymer electrolyte (GPE), which can suppress the Li corrosion in a high‐concentration electrolyte based on lithium bis(fluorosulfonyl)imide (LiFSI) and a weakly solvating solvent ( N , N ‐dimethylsulfamoyl fluoride, FSA). The lithium‐ion space charges formed at the SICC/GPE interface reduce the coordination of anions in the composite layer, suppressing their decomposition. A Li | LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) pouch bi‐cell with a composite layer‐coated thin lithium metal anode (N/P = 1, thickness: 20 µm) delivers projected gravimetric (316 Wh kg −1 ) and projected volumetric (1433 Wh L −1 ) energy densities and exhibits stable operation for 350 cycles, with 70% capacity retention at 1/3 C charge–discharge rate. The engineering of the solvation structure through the inorganic–organic composite layer represents a practical strategy for developing corrosion‐resistant lithium metal anodes in high‐concentration electrolytes.