An electrolyte for a battery comprises a lithium organoborate salt in a lactone and a low viscosity solvent. The lithium organoborate salt may comprise LiBOB, or a mono[bidentate]borate salt. The lactone may comprise gamma butyrolactone. The low viscosity solvent may comprise a nitrile, an ether, a linear carbonate, or a linear ester. The electrolyte is suitable for use in lithium ion batteries having graphite negative electrodes. Batteries using this electrolyte have high conductivity, low polarization, and high discharge capacity.