《Nonafluorobutyl Ether Enhancing Stability of Fluorobenzene-based Diluted High-Concentration Electrolyte in High-Voltage Lithium Metal Batteries》

The development of stable electrolytes for high-voltage lithium metal batteries (LMBs) is crucial for advancing battery technology. Diluted high-concentration electrolytes (DHCE) have shown promise in enhancing interfacial stability, yet challenges persist due to the thermodynamic instability associated with conventional hydrofluoroether diluents and the interphase issues of monofluoroaromatic hydrocarbon diluents under high voltage conditions. In this study, we propose the incorporation of methyl 1,1,2,2,3,3,4,4,4-nonafluorobutyl ether (CNFE) as an additive to fluorobenzene (FB)-based DHCE for high-voltage LMBs. The CNFE with molecular structure devoid of β-hydrogen guarantees thermodynamic stability of FB-based DHCE compared to conventional hydrofluoroethers-based DHCE. Moreover, CNFE promotes the forming of a LiF-rich and stable solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI). Consequently, Li||LiNi0.8Co0.1Mn0.1O2 (NCM811) cell demonstrates a remarkable capacity retention of 84.8% at 700th cycle at a high cutoff voltage of 4.4 V.