Lithium Nitrate Regulated Sulfone Electrolytes for Lithium Metal Batteries

Abstract

The electrolytes in lithium metal batteries have to be compatible with both lithium metal anodes and high voltage cathodes, and can be regulated by manipulating the solvation structure. Herein, to enhance the electrolyte stability, lithium nitrate (LiNO 3) and 1,1,2,2‐tetrafuoroethyl‐2′,2′,2′‐trifuoroethyl(HFE) are introduced into the high‐concentration sulfolane electrolyte to suppress Li dendrite growth and achieve a high Coulombic efficiency of >99 % for both the Li anode and LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathodes. Molecular dynamics simulations show that NO 3− participates in the solvation sheath of lithium ions enabling more bis(trifluoromethanesulfonyl)imide anion (TFSI−) to coordinate with Li+ ions. Therefore, a robust LiNxOy−LiF‐rich solid electrolyte interface (SEI) is formed on the Li surface, suppressing Li dendrite growth. The LiNO 3‐containing sulfolane electrolyte can also support the highly aggressive LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathode, delivering a discharge capacity of 190.4 mAh g−1 at 0.5 C for 200 cycles with a capacity retention rate of 99.5 %.