Polymeric concentrated electrolyte enables simultaneous stabilization of electrode/electrolyte interphases for quasi-solid-state lithium metal batteries

To achieve next-generation lithium metal batteries (LMBs) with desirable specific energy and reliability, the electrolyte shown simultaneously high reductive stability toward lithium metal anode and oxidative stability toward high-voltage cathode is of great importance. Here, we report for the first time that high-concentration lithium bis(fluorosulfonyl)imide (LiFSI) initiates ring-opening polymerization of 1,3-dioxolane in presence of ethylene carbonate and ethylmethyl carbonate to produce in-situ a novel polymeric concentrated quasi-solid electrolyte (poly-CQSE). The unique poly-CQSE with 10 M LiFSI forms a mixed-lithiophobic-conductive LiF-Li3N solid electrolyte interphase on lithium metal anode, and a F-rich conformal cathode electrolyte interphase on LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode simultaneously. As a result, the poly-CQSE not only enables stable Li plating/stripping of metallic Li anode at a sound Coulombic efficiency of 95.3% without dendrite growth, but also enables a stable cycling of the Li||NCM523 quasi-solid-state LMB at a capacity retention of 94% over 100 cycles.