Neutron diffraction study on layered rocksalt Li1−xNi1+xO2 at high temperature

Lithium diffusion pathway in Li1−xNi1+xO2 with the α-NaFeO2 structure was elucidated using neutron diffraction measurements at high temperatures. In the layered structure of space group R3̄m, lithium and nickel ions occupy the octahedral 3a and 3b sites, respectively, at room temperature. Above 493 K, a part of lithium shifted from the 3a site to the interstitial 6c site which shares faces to the LiO6 octahedra at the 3a site. This indicates that the octahedral 3a and the interstitial tetrahedral 6c sites participate in the lithium ionic diffusion at high temperatures.