Synthesis of Fire-Extinguishing High-Voltage Electrolytes for Safe Batteries

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The lack of a suitable alternative solvent has hindered further exploration of new functional electrolytes. Herein we design and synthesize a fluorinated cyclic phosphate solvent, 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide (TFEP), for use in LIBs. An electrolyte formula composed of 0.95 M LiN(SO2F)2 in TFEP/2,2,2-trifluoroethyl methyl carbonate shows excellent non-flammability with zero self-extinguishing time and enables the highly stable operation of graphite anodes (ca. 0.1 V vs lithium) and high-voltage LiNi0.5Mn1.5O4 cathodes (ca. 4.7 V vs lithium), thereby outperforming the traditional electrolytes. This work opens new frontiers in electrolyte developments toward safe LIBs with higher energy densities, which was recently accepted for publication on Nature Energy.