Processing‐Dependent Performance of the LiNiO$_2$ Cathode in Lithium‐Ion Batteries

The electrochemical performance of the LiNiO$_2$ cathode is highly sensitive to minor deviations in synthesis and handling. Here, we study the effects of particle size of the precursor cathode active material (pCAM), the mixing process of pCAM and lithium source, and the impact of various atmospheres on the properties of LiNiO$_2$. For LiNiO$_2$ made from 10  µm pCAM, a performance improvement after (Nb-based) surface coating was only observed when the material was sieved in a dry room. For LiNiO$_2$ made from 4  µm pCAM, the method used to mix the hydroxide precursors (prior to calcination) proved to be decisive for the final properties, with manual grinding leading to smaller (more uniform) primary particles and enhanced stability compared to mixing with a laboratory blender. Furthermore, brief exposure of the as-prepared LiNiO$_2$ to different atmospheres resulted in some increase in initial capacity but had only a minor effect on overall performance. Notably, applying a protective surface coating did not improve cyclability, suggesting that its effectiveness depends on a variety of parameters. The results underscore the importance of carefully controlling synthesis parameters and handling conditions for LiNiO$_2$ and emphasize that detailed reporting of these factors is essential for reproducibility and further optimization.