Benchmarking the Safety Performance of Organic Electrolytes for Rechargeable Lithium Batteries: A Thermochemical Perspective

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.