COMPARISON OF LI-7 NMR INVESTIGATIONS( TRANSPORT IN NA1+XV3O8 AND LI1+XV3O8 BY LI)

Li-7 NMR studies have been carried out on some vanadium bronzes of int erest as cathodes in rechargeable Li cells. Li0.63NaV3O8, amorphous Li V3O8 (both prepared at low temperature), Li0.59NaV3O8 and crystalline LiV3O8 (both prepared at high temperature) have been investigated by m easuring linewidth, spin-lattice and spin-spin relaxation times. For t he first three samples above, it was possible to calculate the self-di ffusion coefficients (10(-11) cm2 s-1 for the Na bronzes and 10(-9) cm 2 s-1 for amorphous LiV3O8). These values are lower than those for the chemical diffusion coefficients measured by electrochemical technique s. This is explained by different contributions to the enhancement fac tor.