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

The lithium metal anode is regarded as a promising candidate in next-generation energy storage devices. Lithium nitrate (LiNO₃) 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 LiNO₃ is rarely utilized in the high-voltage window provided by carbonate electrolyte. Dissolution of LiNO₃ in carbonate electrolyte is realized through an effective solvation regulation strategy. LiNO₃ can be directly dissolved in an ethylene carbonate/diethyl carbonate electrolyte mixture by adding trace amounts of copper fluoride as a dissolution promoter. LiNO₃ protects the Li metal anode in a working high-voltage Li metal battery. When a LiNi_0.80Co_0.15Al_0.05O₂ cathode is paired with a Li metal anode, an extraordinary capacity retention of 53 % is achieved after 300 cycles (13 % after 200 cycles for LiNO₃-free electrolyte) and a very high average Coulombic efficiency above 99.5 % is achieved at 0.5 C. The solvation chemistry of LiNO₃-containing carbonate electrolyte may sustain high-voltage Li metal anodes operating in corrosive carbonate electrolytes.