The spin-lattice relaxation time of 7Li was measured in LiCoO2, Li0.5NiO2 and LiNiO2 at temperatures ranging from 77 to 680K. The data for higher temperatures were explained in terms of a relaxation mechanism for the diffusive motion of Li+ ion defects. The activation energy for the diffusion of Li+ in all of the materials was estimated to have almost the same value, of 0.08eV. From an analysis which was based upon the fluctuating field model, with diffusion of Li+ defects, the predominant mechanism of spin-lattice relaxation in LiCoO2 was expected to be quadrupole interaction, in the high-temperature region. On the other hand, relaxation in LiNiO2 was expected to be governed by magnetic dipole interaction between the Li nucleus and paramagnetic Ni ions in the Li layer.

NMR Investigation on the Motion of Li+ Defects in LiCoO2 and LiNiO2. K.Nakamura, M.Yamamoto, K.Okamura, Y.Michihiro, I.Nakabayashi, T.Kanashiro: Solid State Ionics, 1999, 121[1-4], 301-6