First principles study of Li diffusion in I-Li₂NiO₂ structure

First principles computations have been used to study Li mobility in the orthorhombic Li₂NiO₂ structure with the Immm space group (I-Li₂NiO₂). Understanding Li mobility in I-Li₂NiO₂ structure other than the conventional layered structure helps extend our understanding of Li transport in different oxide structures. Our results indicate that I-Li₂NiO₂ is a reasonably good lithium ionic conductor with two-dimensional diffusion when the structure is maintained upon lithiation or delithaion. It is predicted that in the orthorhombic cell the activation barriers along the b axis and diagonal direction between a and b axes are fairly low, ensuring the facile lithium diffusion along those directions, while migration along the a axis is unlikely given the very high activation barrier (∼2 eV).