<p>The widespread use of lithium-ion batteries (LIBs) has led to environmental concerns and exacerbated the scarcity of essential minerals, underscoring the urgent need for effective recycling strategies. Among various recycling methods, the hydrometallurgical process is distinguished by its energy efficiency and minimal environmental impact. Nickel-metal hydride (Ni-MH) batteries are a significant source of nickel sulfate (NiSO₄) for hydrometallurgical recycling due to their substantial nickel content. A significant challenge arises from the effective separation of lanthanum (La), which results in at least 20 ppm of La being present in the recycled NiSO₄. This study explores a critical aspect of the recycling process: the impact of La³⁺ impurities, introduced through recycled NiSO₄, on the performance of the synthesized nickel-rich cathode materials. We conducted a thorough investigation into how La³⁺ influences morphology and structural integrity during both the synthesis of precursors and the production of cathode materials. Our findings indicate that La³⁺ impurities do not adversely affect the morphology or structural integrity of the cathode precursors relative to virgin materials. However, higher concentrations of La³⁺ reduce the discharge capacity with enhanced cycle stability by minimizing cation mixing between lithium (Li⁺) and nickel (Ni²⁺) ions within the cathode. This stability is crucial for extending battery life. Therefore, controlling the concentration of La³⁺ impurities is essential for optimizing the electrochemical performance of recycled cathode materials.</p> Graphical Abstract <p></p>