Understanding local Li+ diffusion in partially disordered LiNiO2

Cation-disordered oxides are promising cathode materials for Li-ion batteries given their high capacities (~ 300 mAhg-1), and chemical versatility. Unlike common layered oxide cathodes, like LiNiO2 (LNO), their disordered cation arrangement enables isotropic, small volume changes for enhanced stability and electrochemical properties. Since its discovery in 1954, LNO has been widely studied given its high operating voltage and electrochemical capacity, but its commercial use has been limited by its thermal instability at high de-lithiation states and fast capacity fade. We have recently developed a method to convert layered LNO into a cation-disordered rock salt (DRS-LNO) via gradual introduction of disorder resulting in an improvement in its electrochemical performance. With this proposal we will use μ⁺SR to investigate the differences in the local Li+ diffusion pathways of new partially disordered LNO (PD-LNO) cathode materials showing different capacity and stability depending on the degree of disorder in the system and without the influence of paramagnetic ions and particle size. This data will complement our neutron total scattering and solid-state NMR data to provide definitive information on the local Li environments and its influence on the Li mobility and capacity in PD-LNO samples. Combining μ⁺SR measurements with our structural data will provide a fundamental understanding on the mechanism behind the differences in capacity and stability observed in these materials.