New polymer electrolytes based on polyethylene glycol diacrylate–LiBF4–1-ethyl-3-methylimidazolium tetrafluoroborate with the introduction of alkylene carbonates

Abstract

Polymer gel electrolytes based on polyethylene glycol diacrylate (PEG DA), salt LiBF4, and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) were synthesized and studied in the presence of propylene carbonate and ethylene carbonate as solvents. The mechanism of ionic transport in the system was studied using electrochemical impedance spectroscopy, liquid mass spectrometry, pulse-field-gradient spin echo NMR spectroscopy. The range of operating temperatures of the gel electrolytes was determined by DSC. The total conductivity at room temperature in these systems is about 10–3 S cm–1. The self-diffusion coefficients on 7Li nuclei in the systems with a solvent attain the values about 10–10 m2 s–1, and in the PEG DA–LiBF4–EMIBF4 system they range from 10–13 to 10–12 m2 s–1. Ternary associates [(EMI)2(BF4)]+ and [Li+(BF4)2]– were found by liquid mass spectrometry to be the main charge carriers.