Dynamics of Li ions in an intercalated polymer electrolyte: a <SUP>7</SUP>Li nuclear magnetic resonance study

The 7Li nuclear magnetic resonance spectra and spin-lattice relaxation rates of lithium ions in an intercalated polymer electrolyte, Li-polyethylene-oxide confined within the galleries of an inorganic layered solid CdPS3, are reported. The spectra show an unusual feature, the appearance above 330 K of quadrupolar satellites, whose splitting increases linearly with temperature, and their absence below this temperature. This behavior is also reflected in the temperature variation of the spin-lattice relaxation rates, which show a minimum at 300 K but above 330 K start decreasing again. Using an anisotropic quantum oscillator model, the observed variation in the 7Li quadrupolar coupling constant is shown to arise from changes in the time average of the electric field gradient as seen by a 7Li nucleus associated with mobile segments of the intercalated polymer