Dynamics in a poly(ethylene oxide)-based nanocomposite polymer electrolyte probed by solid state NMR

Novel nanocomposite polymer electrolytes have been synthesized by intercalation of poly(ethylene oxide) into various layered silicates. In this work we use solid state NMR to probe dynamics associated with both the cations and the polymer over a broad temperature range. Spin-lattice relaxation studies reveal the influence of the polymer backbone dynamics on the Li-7(+) T-l, and we discuss why such measurements need to be interpreted with care. Cation dynamics are separated from that of the polymer by an analysis of the temperature dependence of the Li-7 spectrum in the presence of paramagnetic impurities fixed in the silicate lattice. The intercalated polymer shows no evidence for either glass or melt transitions, and over the same temperature range exhibits thermally-activated polymer reorientation. Over the same broad temperature range, Li+ cations prove to be mobile with the same activation energy. Such measurements appear to indicate that cation diffusion is much slower than polymer reorientation in these systems.