Partially Solvated Cosolvent Induced Reconfiguration of Solvation Structure and Helmholtz Layer for Lithium Metal Battery

Reconfiguring the electrolyte microstructure containing Li+ solvation structure in bulk electrolyte and Helmholtz layer (HL) near the interface presents a compelling strategy in the design of electrolytes. In this work, ionic liquids (ILs) and partially solvated fluorobenzene (FB) build the unique Li+ coordination state modulated by FB and dominated by anions as well as a HL enriched in non-sacrificial cations on charging. As an important part to regulate the micro environment, FB not only enhances the iontransport kinetics of electrolyte and promotes the interaction of Li+-FSI-,but alsoparticipate in constructing a robust solid electrolyte interphase (SEI). Interestingly, FBindirectly promotes the enrichment of ILs' cations at the HL, which is beneficial foruniform Li metal deposition due to its electrostatic shielding effect. Li metal batteriesutilizing this electrolyte demonstrate impressive cycling performance at a high rate(approximately 89% capacity retention after 2,500 cycles at 5C). Furthermore, thesecells show excellent high-temperature performance, maintaining 71% of the initialcapacity after 1,000 cycles at 70°C and 10C rate.