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) ‖LiNi0.8Co0.1Mn0.1O2 (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 LiNi0.8Co0.1Mn0.1O2‖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.