Composition,structure, and performance of Ni-based cathodes in lithium ion batteries

With the rapid development of electric vehicles, Ni-based cathodes attract increasing attention as used in power batteries due to their high capacity and low cost. However, Ni-based cathodes are faced with several problems, such as Li/Ni disorder, cycle capacity degrading, poor storage in air, and thermal instability. This review carefully compared the structure difference between LiNiO₂ and LiCoO₂ and concluded that the electronic structure of Ni³⁺ determined the instability of LiNiO₂. The degrading mechanism during long cycle was discussed in the second part and it could be attributed to the surface properties. Moisture sensitive severely restricts the application of Ni-based cathodes due to the gelation in slurry making and gas released in batteries. Some possible mechanisms proposed by previous researchers were reviewed in the third part and a new interpretation on the basis of diffusion was also suggested. Lastly, the nature of thermal instability of Ni-based cathodes was presented.