Novel Concentrated Li[(FSO2)(n-C4F9SO2)N]-Based Ether Electrolyte for Superior Stability of Metallic Lithium Anode

Lithium (fluorosulfonyl)(n-nonafluorobutanesulfonyl)imide [LiRFSO2)(n-C4F9SO2)N] (LiFNFSI)] is investigated as a conducting salt, which can form a relatively stable solid-electrolyte-interphase film in concentrated ether electrolyte to achieve favorable protection for lithium metal anodes. Li vertical bar Cu and Li vertical bar Li cells with concentrated LiFNFSI-based electrolyte have been demonstrated to display high average Coulombic efficiency (approximate to 97%) and excellent cycling stability (over 1,000 h) of metallic lithium anodes, compared to concentrated lithium bis(trifluoromethanesulfonyl)imide [Li[N(SO2CF3)(2)] (LiTFSI)]-based electrolyte. The morphologies and compositions of the lithium-metal anode surface are also comparatively analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Moreover, superior electrochemical performance in the concentrated LiFNFSI-based electrolyte for LiL vertical bar FePO4 cells is also presented herein. These results indicate that concentrated LiFNFSI-based electrolyte is a promising candidate for metallic lithium rechargeable batteries.