The use of lithium-ion batteries to power electric vehicles (EVs) is all well and good until cold weather sets in. The liquid electrolyte transporting charge-carrying particles between electrodes starts to freeze at sub-zero temperatures, undermining EV charging.

A new electrolyte formulated by researchers from U.S. Argonne National Laboratory and University of California Berkeley doesn’t let freezing weather clamp down on the charging process. The fluorination position and the degree of fluorination of ethyl acetate solvent was optimized to yield an electrolyte that performs well even in sub-zero temperatures.

The fluorinated electrolyte was demonstrated to retain stable energy storage capacity for 400 charge-discharge cycles at -4° F during laboratory tests. Even at that sub-zero temperature, the capacity was equivalent to that of a cell with a conventional carbonate-based electrolyte at room temperature.

The low-temperature electrolyte described in Advanced Energy Materials can be applied to energy storage for electric grids and consumer electronics like computers and phones in addition to EV batteries. As an added bonus, the antifreeze electrolyte is much safer than the carbonate-based electrolytes currently in use, since it will not catch fire.