Developing nonflammable organic electrolytes has been
regarded
as one of the most valuable strategies for tackling the safety issues
of rechargeable lithium batteries. However, a quantitative and precise
evaluation of electrolyte safety remains challenging mostly because
of the inconsistent measurement conditions and the lack of a basic
reference system. In this work, we performed a benchmark study on
the safety of organic electrolytes by characterizing with cone calorimetry
the thermochemistry of various types of single-solvent electrolytes.
An intrinsically safe organic electrolyte should show simultaneous
low total heat release, low maximum heat release rate, long time to
ignition, and short self-extinguishing time. Experimentally, a “cocktail”
therapy combining polyfluorinated solvents and high-boiling point
solvents is found to be the optimal choice for composing nonflammable
electrolytes. Our results help to identify promising electrolyte components
and shed light on the reasonable design of high-safety organic electrolytes
for advanced rechargeable batteries.