The functional electrolyte containing 2-fluorobenzenesulfonyl fluoride (2FF) additive enhances the performance of LiNi0.8Co0.1Mn0.1O2/graphite batteries by stabilizing the cathode interface

Abstract

A functional electrolyte containing conventional carbonate esters solvents, LiPF6 salt, and novel 2-fluorobenzenesulfonyl fluoride (2FF) additive is developed to stabilize the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode interface and enhance the performance of NCM811/graphite lithium-ion batteries (LIBs). It is indicated that due to the unique C-F and sulfonyl fluoride groups of 2FF, the NCM811/Li half batteries containing 2% 2FF electrolyte show the highest cycling performance, a coulombic efficiency of 98.4% and a capacity retention of 89.4% are obtained after 100 cycles at 0.5C. And compared to the pouch NCM811/graphite full batteries with blank electrolyte, the long cycle performance of the batteries with 2% 2FF is also increased after 500 cycles at 45 °C, the discharge capacity retention rate retains at 80.04% and the coulombic efficiency closes to 100%. The spectroscopic characterization and theoretical calculation demonstrate that the electrolyte with 2FF additive preferentially react and generate uniform CEI film. These results show that this 2FF-containing electrolyte can stabilize NCM811 cathode interface, revealing a promising prospect of the commercial application of high-nickel LIBs.