Tri-functionalized electrolyte additive as an interfacial stabilizer for lithium metal anodes

Li metal has received noticeable interest as a post-anode material, however, many critical hurdles remain in its application in conventional batteries. Herein, we have designed and prepared an additive, the AF, that is functionalized by three individual functional groups: vinyl-, bis(fluorosulfonyl)imide-, and acetal functional groups. The AF-additive promotes forming solid-electrolyte interphase (SEI) layers at the Li metal interface via electrochemical reduction at a higher potential than that found in the carbonate-based electrolyte, which is predominately composed of inorganic species, such as lithium fluoride, rather than polycarbonate. The ionic conductivity of the electrolyte with the AF-additive is well retained even when the amount of AF-additive is increased because the acetal functional group may form acetal–Li+ complexes, which encourages Li+ migration. The AF-additive controlled electrolyte offers improved cycling retention in the both Li/Li symmetric cell and Li/NCM cell because the AF-additive not only effectively suppresses electrolyte decomposition at the interface of Li metal but also inhibits the formation of Li dendrites based on enhanced Li metal stability.