The motion of Li+ defects and the magnetic behavior were investigated by 7Li-NMR technique. The spin–lattice relaxation time T1, the spin–spin relaxation time T2 and the Knight shift K were measured in de-lithiated LixNiO2 from 4.2 to 650K. The motional narrowing observed in de-lithiated samples above 200K indicated that a remarkable motion of Li+ defects exists. A contribution from a development of the magnetic correlation between Ni3+ spins appeared in T1-1 and K below 100K in LiNiO2. The increase for T1-1 and K at low temperatures was strongly suppressed with decreasing x. This implied that non-magnetic Ni4+ ion produced by vacancies would cut off the magnetic correlation between inter/intra-Ni layer. The increase of vacancies promotes the motion of Li+ defects and substantially varies the magnetic behavior. The magnetic relaxation process arising from Ni3+ spins which was dominant at low temperatures changed into a relaxation process based on the motion of Li+ defects with increasing temperature.

NMR Study of the Motion of Li+ Defects and the Magnetic Behavior in LixNiO2. K.Nakamura, M.Yamamoto, K.Okamura, R.M.Mahbubar, Y.Michihiro, I.Nakabayashi, T.Kanashiro: Solid State Ionics, 2002, 152-153, 241-6