Silyl and Silyl/Carbonate Blend Electrolytes for Lithium-Ion Battery Applications

Abstract

Silyl glycol molecules and silyl nitrile molecules were used to prepare electrolytes with the salts LiPF6 and LiTFSI, Ionic conductivities of silyl electrolytes at 298 K range from 1.0 to 2.3 mScm-1 for salt concentrations at 1 M. Ionic conductivities of the silyl solvent/carbonate blend electrolytes increase, achieving ionic conductivities at 298 K of 5-6 mScm-1. From PFG-STE NMR experiments we find higher lithium transference numbers in silyl electrolytes than those in analogous cyclic carbonate electrolytes. The lithium transference numbers increase with increasing temperature for PF6 - electrolytes while those based on TFSI- electrolytes decrease with increasing temperature. From both the ionic conductivity and NMR diffusion measurements, we have calculated the extent of ion dissociation in these electrolytes. Ion dissociation generally decreases with increasing temperature from 300-330 K.