An electrolyte composition includes (a) a solvent composition including at least one hydrofluoroether compound, the hydrofluoroether compound including two terminal fluoroalkyl groups and an intervening substituted or unsubstituted oxymethylene group, each of the fluoroalkyl groups including only one hydrogen atom and, optionally, at least one catenated (that is, in-chain) heteroatom, with the proviso that, when the oxymethylene group is unsubstituted, at least one of the terminal fluoroalkyl groups is branched and/or includes at least one catenated heteroatom; and (b) at least one electrolyte salt.