Lithium Nitrate Solvation Chemistry in Carbonate Electrolyte Sustains High‐Voltage Lithium Metal Batteries

Abstract The lithium metal anode is regarded as a promising candidate in next‐generation energy storage devices. Lithium nitrate (LiNO 3 ) is widely applied as an effective additive in ether electrolyte to increase the interfacial stability in batteries containing lithium metal anodes. However, because of its poor solubility LiNO 3 is rarely utilized in the high‐voltage window provided by carbonate electrolyte. Dissolution of LiNO 3 in carbonate electrolyte is realized through an effective solvation regulation strategy. LiNO 3 can be directly dissolved in an ethylene carbonate/diethyl carbonate electrolyte mixture by adding trace amounts of copper fluoride as a dissolution promoter. LiNO 3 protects the Li metal anode in a working high‐voltage Li metal battery. When a LiNi 0.80 Co 0.15 Al 0.05 O 2 cathode is paired with a Li metal anode, an extraordinary capacity retention of 53 % is achieved after 300 cycles (13 % after 200 cycles for LiNO 3 ‐free electrolyte) and a very high average Coulombic efficiency above 99.5 % is achieved at 0.5 C. The solvation chemistry of LiNO 3 ‐containing carbonate electrolyte may sustain high‐voltage Li metal anodes operating in corrosive carbonate electrolytes.