First principles study of Li diffusion inI-Li2NiO2structure

First principles computations have been used to study Li mobility in the orthorhombic ${\text{Li}}_{2}{\text{NiO}}_{2}$ structure with the $Immm$ space group $({\text{I-Li}}_{2}{\text{NiO}}_{2})$. Understanding Li mobility in ${\text{I-Li}}_{2}{\text{NiO}}_{2}$ structure other than the conventional layered structure helps extend our understanding of Li transport in different oxide structures. Our results indicate that ${\text{I-Li}}_{2}{\text{NiO}}_{2}$ 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 $(\ensuremath{\sim}2\text{ }\text{eV})$.