New electrolytes based on glutaronitrile for high energy/power Li-ion batteries

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 6 V versus Li⁺/Li for the 1 M LiTFSI electrolytes. Glutaronitrile and its ethylene carbonate electrolyte solutions show high ionic conductivities and low viscosities reaching 5 mS cm⁻¹ and 7 cP, respectively, at 20 °C. Aluminum corrosion tests of the solutions showed an improved protective resistance up to 4.4 V. 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.