To distinct lithium diffusive species for polymer gel electrolytes containing LiBF_4, propylene carbonate (PC) and PVDF

摘要

Polymer gel electrolytes have been prepared using lithium tetrafluoroborate (LiBF_4), propylene carbonate (PC) and polyvinylidene fluoride (PVDF) at 20% and 30% concentration by mass. Self diffusion coefficients have been measured using pulse field gradient nuclear magnetic resonance (PFG-NMR) for the cation and anion using ~7Li and ~(19)F resonant frequencies respectively. It was found that lithium ion diffusion was slow compared to the much larger fluorine anion likely resulting from a large solvation shell of the lithium. Lithium ion diffusion measurements exhibited two distinct diffusive species, whereas the fluorine ions exhibited only a single diffusive species.