Glutaronitrile, CN[CH2]3CN, is evaluated as a co-solvent in thermally and (anodically) electrochemically stable electrolyte mixtures suitable for high energy/power Li-ion batteries. Linear sweep voltammetry scans indicate an electrochemical anodic stability of more than 6V versus Li+/Li for the 1M LiTFSI electrolytes. Glutaronitrile and its ethylene carbonate electrolyte solutions show high ionic conductivities and low viscosities reaching 5mScm−1 and 7cP, respectively, at 20°C. Aluminum corrosion tests of the solutions showed an improved protective resistance up to 4.4V. Lithium ion batteries incorporating graphite as an anode and LiCoO2 as the cathode material were assembled using a glutaronitrile electrolyte mixture, whose stability on graphite was greatly enhanced by the use of ethylene carbonate as a co-solvent and Li (bioxalatoborate) (LiBOB) as a co-salt, and these cells showed moderately good discharge capacities with low capacity fade up to the 100th cycle.