Nonafluorobutane-1-Sulfonic Acid Induced Local High Concentration Additive Interface for Robust SEI Formation of High-Voltage (5 V-Class) Lithium Metal Batteries

摘要

To optimize anode and cathode degradation issues in high-voltage (5 V-class)lithium metal batteries (LMBs), robust solid–electrolyte interfaces (SEI)on the surface of both anode and cathode are highly desired. Here, anonafluorobutane-1-sulfonic acid (NFSA) additive is introduced to assistin the formation of the more stable and robust SEI to protect bothanode and cathode. Typically, local high concentrations of lithiumnonafluorobutane-1-sulfonate (NFSALi) and nonafluorobutane-1-sulfonateanion (NFSA?) could be achieved at the surface of anode and cathoderespectively, through spontaneous chemical processes. The lowestunoccupied molecular orbital energy of NFSALi is lower and the highestoccupied molecular orbital (energy of NFSA~? is higher than electrolytesolvents. Thus, conformal and dense SEI passivation films are generated onthe surface of both anode and cathode derived from electrochemicaldecomposition of NFSALi and NFSA~?, respectively. Consequently, stableoperation of Li metal anode and high-voltage cathode are realized. TheLiNi_(0.5)Mn~(1.5)O~4(LNMO)//Li LMBs with NFSA-containing electrolyte showgreat cycling stability with 93% capacity retention after 400 cycles and morestable Coulombic efficiency. This work specifies the double functions of NFSAas an interfacial layer forming additive to solve the degradation problems ofhigh-voltage (5 V-class) LMBs, enabling high-energy LMBs with significantlyimproved battery performance.