Achieving a Practical High-Voltage Lithium Metal Battery by the Use of a High-Concentration Fluorinated Carbonate Electrolyte

Lithium metal batteries with ultrahigh-specific energy densities can be realized by combining lithium metal anodes with high-voltage and high-capacity lithium-rich manganese oxide cathodes. Their practical application is largely hindered by the notorious dendrite growth of lithium metal anode, fast structure degradation of cathode, and insufficient electrode–electrolyte interphase kinetics that arise from severe side reactions between conventional electrolytes and very active lithium metals. Here, the use of a high-concentration fluorinated carbonate electrolyte consisted of methyl 2,2,2-trifluoroethyl carbonate as solvents and lithium bis(fluorosulfonyl)imide as salts can significantly improve the electrochemical stability of the electrolytes and prohibit the structural failure of lithium metal. In Li||LR-NCM114 pouch cells, the cycling performance of the pouch cell was greatly improved (92.3% capacity retention over 100 cycles). Furthermore, a pouch cell with a capacity of 6.2 Ah is fabricated and achieves an ultrahigh energy density over 500 Wh kg^–1. Our work has explored the application of high-concentration fluorinated carbonate electrolytes in high-voltage lithium metal batteries with a high energy density.