Non-fluorinated electrolytes with micelle-like solvation for ultrahigh energy density lithium metal batteries

Electrolyte engineering plays a critical role in enabling lithium (Li) metal batteries. However, the simultaneous realization of anion-rich solvation structure and high ionic conductivity of electrolytes via solvation structure design remains challenging. Here, we report a low-cost, non-fluorinated electrolyte with a micelle-like solvation structure by introducing amphiphilic n-butyl methyl ether (MNBE) into lithium bis(fluorosulfonyl)imide (LiFSI)/1,2-dimethoxyethane (DME) for stable Li metal batteries. MNBE can effectively promote Li+-FSI- coordination through steric crowding. Meanwhile, the inert alkyl chains of MNBE can mitigate the reaction between electrolyte and Li metal due to their lithiophobicity. Specifically, the micelle-like, non-fluorinated electrolyte exhibits an ionic conductivity as high as 12.55 mS cm-1 and its anion-rich solvation structure promotes the formation of LiF-rich solid-electrolyte-interphase. We constructed a 7.3 Ah Li||NMC811 pouch cell employing this electrolyte under harsh conditions, exhibiting ultrahigh specific energy of 503.7 Wh kg-1 with impressive cycling stability of 84.1% capacity retention after 100 cycles.