Managing ammonia-alkali balance to control precursor characteristics in co-precipitation process for enhanced electrochemical performance of nickel-rich cathode materials

The pH value and total ammonia concentration are critical parameters in the preparation of Ni-rich cathode material precursors by co-precipitation. These parameters play crucial roles in determining the morphological characteristics and crystal structures of the precursors. This paper explores the effects of pH value and ammonia concentration during co-precipitation reactions, examines the relationships between precursor microstructure parameters and macroscopic particle characteristics, and establishes the correlation between the crystal structure of active materials and electrochemical properties alongside precursor particle characteristics. The results demonstrate that the precursors with a higher tap density are more likely to produce nickel-rich active materials with superior crystal structure and electrochemical properties, contingent on the higher pH value and the appropriate ammonia concentration at that pH value. Within the range of experimental conditions in this study, the optimal process conditions were determined to be pH = 11.8 and ammonia concentration = 0.97 mol l−1.