Design of a Teflon-Like Anion for Unprecedently Enhanced Lithium Metal Polymer Batteries

摘要

Rechargeable lithium metal polymer batteries (LMPBs) utilizing solid polymerelectrolytes (SPEs) have gained increasing attention during the past fivedecades, owing to the superior flexibility, good process-ability, and noleakageof SPEs versus traditional non-aqueous liquid and inorganic solidelectrolytes. Undoubtedly, among all of the SPE components, salt anionshave a significant impact on the overall performances of LMPBs. Yet, lithiumbis(trifluoromethanesulfonyl)imide, being commonly applied in the prevailingSPEs shows relatively poor interphasial stability toward lithium metal(Li°) anode, which greatly impedes the long-term cycling stability of LMPBs.Herein, a Teflon-like sulfonimide salt, lithium bis(n-nonafluorobutanesulfonyl)imide (LiNFSI), is ingeniously selected for modulating the properties of solid–electrolyte-interphases on the anode side, in view of the peculiar film-formingability of n-nonafluorobutanesulfonyl group. In-depth physical, chemical, andelectrochemical characterizations demonstrate that the incorporation of theTeflon-like anion, NFSI?, results in a remarkably enhanced electrochemicalstability between Li° anode and SPEs, with a negligible expense of ionic conductivities.The Teflon-like sulfonimide anion suggested in this work providesan elegant path toward the wider application of LMPBs in energy storage andelectric vehicles in the near future.