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

To mitigate the high corrosivity of weakly solvating solvent-based electrolytes toward lithium metal, a composite material forming a Li⁺ space charge is introduced at the lithium metal-electrolyte interface. The Li⁺ space charge generated at the interface between the single-ion-conducting ceramic and polymer electrolyte interacts weakly with anions, thereby delaying the depletion of liquid electrolytes in lithium metal batteries.

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_0.8Co_0.1Mn_0.1O₂ (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.