Effect of nanosized SiO2 on the transport properties of solventless P(EO)20LIBETI polymer electrolytes: a solid-state NMR study

An extensive NMR investigation of filler-free and SiO2 nanoparticle-containing P(EO)20LiBETI polymer electrolytes prepared through a solvent-free procedure is reported. 7Li and 19F NMR spectra, spin-lattice relaxation times and self-diffusion coefficients were measured in the temperature range extending from 25 to 100 °C. There was essentially no difference in the DLi for filler-free and nanosized SiO2-containing P(EO)20LiBETI at T≥80 °C. The DF showed differences at T≤90 °C, with the SiO2-containing P(EO)20LiBETI having the greater DF. Discrepancies between calculated and measured ionic conductivity are attributed to variable length scale diffusion within heterogeneous media, rather than ion pairing effects.