Prolonged Life Lithium Metal Batteries Enabled by Introducing Abundant Lithium Nitrate in Commercial Carbonate Electrolytes

Carbonate electrolytes have been extensively used as commercial electrolytes in lithium-ion batteries (LIBs) because of its high oxidative stability. However, the organic-inorganic solid electrolyte interphase (SEI) formed on the lithium (Li) metal surface is too fragile to endure huge volume fluctuation during Li plating/stripping cycles in carbonate electrolytes. Herein, a chemically stable inorganic-rich SEI was constructed on Li metal anodes by dissolving 5.5 M LiNO3 in N,N-dimethylformamide (DMF) into carbonate electrolytes as an additive. The Li+ solvation structure coordinated with NO3- and DMF molecules favors the formation of LixNy, LiNxOy, and LiF in the SEI film, which have been proved to increase the interfacial energy and improve the ionic diffusion as well as the mechanical strength of the SEI. Therefore, the designed carbonate electrolyte enhances the stable cycling of Li symmetric cells up to 700 h, with a high Coulombic efficiency (CE) of 99.0 % by Aurbach CE test. When paired with LiFePO4 cathode, the coin cells achieve an outstanding average CE of 99.5 % and 86.5 % retention of initial capacity after 300 cycles.