Lithium Metal Batteries Enabled by Synergetic Additives in Commercial Carbonate Electrolytes

Abstract

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-Li 3 N SEI is designed in commercial 1 M LiPF 6 /EC-DMC electrolytes by introducing lithium nitrate (LiNO 3 ) 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 LiNO 3 . The comprehensive characterizations and simulations demonstrate that the synergistic interaction of LiNO 3 and FEC additives alters the solvation structure of 1 M LiPF 6 /EC-DMC electrolytes and forms additive-derived LiF-Li 3 N SEI, which increases the average Li CE up to 99.6% in 100 cycles. The designed carbonate electrolyte enables the Li/LiNi 0.80 Co 0.15 Al 0.05 O 2 (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.