High Capacity Ni Rich Materials as Advanced Cathodes for Li-ion Batteries

The cathode material utilized in lithium-ion batteries for electric vehicles (EV) nowadays is LiNi_0.85Co_0.10Al_0.05O₂, which belongs to a family of layered structure Ni-rich transition metals oxides Li-(Ni-Co-Mn)O₂. They provide high reversible capacity (200-250 mAhg^-1) and high operating voltage (~3.8 V vs. Li/Li⁺) which are very essential for the EV application. However, these materials in turn have severe drawbacks like synthesizing the material in exact stoichiometry, long-term electrode cyclability, and thermal runaway. By keeping the above issues, much work has been carried out in Ni-rich cathode materials to realize their full potential as next-generation cathodes for LIBs.

We aimed in the present investigation to reduce the cationic disorder in Li-(Ni-Co-Mn)O₂ by partial metal ion substitution (doping) in the lattice by Zr⁴⁺, Mo⁶⁺, W⁶⁺ dopants. This not only enhances the reversible capacity and improves the rate capability of the electrode but also stabilizes the structure. We also coated these materials with a thin film of aluminum oxide (by atomic layer deposition) that can protect the surface from highly reactive electrolyte components. The above modified Ni-rich materials were analyzed through various structural and electrochemical techniques in order to understand the structure and property relationship and the mechanisms towards their performance.