Synthesizing an inorganic-rich solid electrolyte interphase by tailoring solvent chemistry in carbonate electrolyte for enabling high-voltage lithium metal batteries

High-voltage (>4.0 V) lithium metal battery (LBM) is considered to be one of the most promising candidates for next-generation high-energy batteries. However, the commercial carbonate electrolyte delivers a poor compatibility with Li metal anode, and its organic dominated solid electrolyte interphase (SEI) shows a low interfacial energy and a slow Li⁺ diffusion ability. In this work, an inorganic LiF-Li₃N rich SEI is designed to enable high-voltage LBM by introducing nano-cubic LiF and LiNO₃ into 1 M LiPF₆ ethylene carbonate (EC)/dimethyl carbonate (DMC) (v:v = 1:1) electrolyte. Specifically, the unique nano-cubic structure of as-synthetized LiF particles achieves its high concentration dissolution in carbonate electrolyte to enhance the interfacial energy of SEI. In addition, tetramethylene sulfolane (TMS) is used as a carrier solvent to dissolve LiNO₃ in the carbonate electrolyte, thereby deriving a Li₃N-rich SEI. As a result, the as-designed electrolyte shows a high average Li plating/striping CE of 98.3% after 100 cycles at 0.5 mA cm⁻²/0.5 mA h cm⁻². Furthermore, it also enables the ultrathin Li (∼50 μm) ‖LiNi_0.8Co_0.1Mn_0.1O₂ (NCM, 4.4 mA h cm⁻²) full cell to deliver a high-capacity retention of 80.4% after 100 cycles with an outstanding average CE of 99.7%. Notably, the practical application prospect of the modified electrolyte is also estimated in LiNi_0.8Co_0.1Mn_0.1O₂‖Li pouch cell with an energy density of 261.2 W h kg⁻¹. This work sheds light on the internal mechanism of Li⁺ transport within the inorganic dominated SEI and provides a simple approach to stabilize the high-voltage LMBs.