A battery electrolyte solution contains a lithium salt dissolved in a solvent phase comprising at least 10% by weight N of (2,2-difluoroethyl) ethyl carbonate. The solvent phase comprises optionally other solvent materials such as 4-fluoroethylene carbonate and other carbonate solvents. This battery electrolyte is highly stable even when used in batteries in which the cathode material has a high operating potential (such as 4.5V or more) relative to Li/Li+. Batteries containing this electrolyte solution therefore have excellent cycling stability.