Lithium Metal Batteries Enabled by Synergetic Additives in Commercial Carbonate Electrolytes

The lithium metal anode is considered as the ultimate choice for high-energy-density batteries. However, the organic-dominated solid electrolyte interphase (SEI) formed in carbonate electrolytes has a low interface energy against metallic Li as well as a high resistance, resulting in a low Li plating/stripping Coulombic efficiency (CE) of less than 99.0% and severe Li dendrite growth. Herein, inorganic-enhanced LiF-Li3N SEI is designed in commercial 1 M LiPF6/EC-DMC electrolytes by introducing lithium nitrate (LiNO3) and fluoroethylene carbonate (FEC) through a small amount of sulfolane (SL) as a carrier solvent owing to the high solubility of SL for both carbonate solvents and LiNO3. The comprehensive characterizations and simulations demonstrate that the synergistic interaction of LiNO3 and FEC additives alters the solvation structure of 1 M LiPF6/EC-DMC electrolytes and forms additive-derived LiF-Li3N SEI, which increases the average Li CE up to 99.6% in 100 cycles. The designed carbonate electrolyte enables the Li/LiNi0.80Co0.15Al0.05O2 (NCA) cell with a lean lithium metal anode (∼50 μm) to achieve an average CE of 99.7% and a high capacity retention of 90.8% after 150 cycles. This work offers a simple and economical strategy to realize high-performance lithium metal batteries in commercial carbonate electrolytes.