Silyl electrolytes are known to be safer alternatives to commercial carbonate electrolyte blends. Silyl solvents with nitrile functionalities have recently been investigated for their chemical stability and increased conductivity relative to those of analogous silyl molecules with oligo(ethylene oxide) substituents. We will report variable temperature ionic conductivity results on ten blends of silyl-nitrile solvents with cyclic carbonate (EC, PC), linear carbonate (EMC, DEC) and methyl butyrate (MB) solvents with LiPF6 or LiTFSA salt. The blending of solvents significantly improved the ionic conductivity over pure silyl-nitrile solvent electrolytes. Methyl butyrate blends exhibited significant increases in conductivity in the low temperature ranges as aided by its physical properties of low melting point and low viscosity, while cyclic carbonate blends maintained the highest conductivity at ambient temperature as previous literature indicates. The degree of ion dissociation, which compares the ionic conductivity and molar conductivity calculated by the Nernst-Einstein equation from ion diffusion measurements, was calculated for all the electrolyte blends over the temperature range of 295 K to 330 K. The degree of ion dissociation (α) was found to have a negative correlation with temperature. All the electrolytes studied surpassed an ambient conductivity of 1.6 mScm-1 and are viable for use in lithium ion batteries on the market.

Ionic conductivities of silyl and carbonate blend electrolytes

251st National Meeting (2016)

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