Al-Coated Ni-Co Hydroxide Cathode Precursor for Stable Battery Cycling

The patent applies preliminary action by coating the nickel-containing composite hydroxide precursor with aluminum hydroxide before the lithium salt is added and the final oxide is formed. This pre-coating approach ensures that aluminum is already in place to stabilize the crystal structure during subsequent processing and battery cycling, while preventing aluminum from interfering with the densification of the nickel-containing hydroxide during the co-precipitation process. The aluminum coating is applied at 0.1-5 mass% of the overall material, which is sufficient for structural stabilization but limited enough to preserve charge/discharge capacity.

The patent segments the aluminum incorporation process into two distinct stages: first, the co-precipitation of nickel-containing composite hydroxide is completed without aluminum to ensure proper densification and crystal formation; second, aluminum hydroxide is coated onto the formed hydroxide particles as a surface layer. This segmentation allows the bulk hydroxide structure to densify properly while the surface aluminum coating provides the desired crystal structure stabilization during subsequent oxide formation and battery cycling.

The patent optimizes the aluminum content parameter to a specific range of 0.1-5 mass% of the overall material, which represents a carefully balanced parameter change. This controlled aluminum concentration is sufficient to provide crystal structure stabilization and improve cycling characteristics, while remaining low enough to minimize the loss of charge/discharge capacity. The parameter is controlled through precise control of the aluminum salt addition amount during the coating process.