Modern generation of polymer electrolytes based on lithium conductive imidazole salts

In this paper the application of completely new generation imidazole-derived salts in a model polymer electrolyte is described. As a polymer matrix, two types of liquid low molecular weight PEO analogues e.g. dimethyl ether of poly(ethylene glycol) of 500 g mol−1 average molar mass (PEGDME500) and methyl ether of poly(ethylene glycol) of 350 g mol−1 average molar mass (PEGME350) were used. Room temperature conductivities measured by electrochemical impedance spectroscopy were found to be as high as 10−3–10−4 S cm−1 in the 0.1–1 mol dm−3 range of salt concentrations. Li+ transference numbers higher than 0.5 were measured and calculated using the Bruce–Vincent method. For a complete electrochemical characterization the interphase resistance stability over time was carefully monitored for a period of 30 days. Structural analysis and interactions between electrolyte components were done by Raman spectroscopy. Fuoss–Kraus semiempirical method was applied for estimation of free ions and ionic agglomerates showing that fraction of ionic agglomerates for salt concentration of 0.1–1 mol dm−3 is much lower than in electrolytes containing LiClO4 in corresponding concentrations.