Effect of ethylene carbonate concentration on the conductivity of carbonate-based electrolytes with LiPF6 for Li-ion batteries

A four-probe pouch-type cell was used to study the influence of carbonate-based electrolyte composition on the total conductivity of polyolefin separator impregnated with electrolyte through the electrochemical impedance spectroscopy. A frequency dispersion of separator with electrolyte is found to be dependent on the volume ratio of ethylene carbonate and ethyl methyl carbonate in an electrolyte solution. The origin of high- and low-frequency relaxation processes obtained from the impedance spectra is discussed. A correlation between the direct current resistance of separator with electrolyte and dissociation degree of electrolyte salt is found.