In situ -formed flexible three-dimensional honeycomb-like film for a LiF/Li₃N-enriched hybrid organic-inorganic interphase on the Li metal anode

The solid-electrolyte interphase (SEI) plays an important role in stabilizing lithium metal anodes for high-energy storage batteries. However, SEI between the lithium metal anode and liquid electrolyte is usually unstable due to nonuniform Li deposition. A stable SEI is considered to be an effective way to control the interfacial structure and improve the stability of lithium metal anodes. Herein, an in situ-formed flexible three-dimensional honeycomb-like poly(2,2,2-trifluoroethyl methacrylate) film (PTFEMA) fabricated by cross-linking lithium nitrate was designed to construct a LiF/Li3N-enriched hybrid organic-inorganic interphase. The predominant species in the hybrid organic-inorganic interphase should possess excellent chemical stability against the Li metal anode in theory according to the calculation results of the higher LUMO energy level and larger LUMO-HOMO gap, which can regulate uniform Li deposition and the growth of large crystalline grains of Li. As a result, the hybrid organic-inorganic interphase achieved excellent reversibility (>98% Coulombic efficiency over 400 cycles) and an ultralow overpotential (about 10 mV) over 1000 h. Meanwhile, the LFP cathode with the developed anode achieved an 89.6% capacity retention after 500 cycles even at a high rate of 10 C. Moreover, the PTFEMA-N film showed hydrophobic but electrolyte wettable features. We hope this study can be applied to next-generation high-energy storage batteries for practical applications in the foreseeable future.