Ammonia Concentration-Directed Preferential Growth Enhancing Lithium-Ion Diffusion in Li-Rich Mn-Based Oxide Cathodes

Ammonia concentration acts as a "multifunctional structure-directing factor" throughout the entire growth of Li-rich Mn-based oxide (LRMO) precursors in coprecipitation process. Thus, this study investigates the effect of ammonia concentration on the precursor structure and morphology evolution. It is verified that ammonia concentration can significantly influence the preferential growth of crystallites and the agglomeration behavior of secondary particles. At an optimized ammonia concentration, the Mn_0.675Co_0.1625Ni_0.1625CO₃ precursor exhibited preferential growth along the (012) crystallographic plane, facilitating an ordered structural arrangement and suppressing the agglomeration of secondary particle. After lithiation, the resulting LRMO material exhibits an enhanced Li⁺ diffusion, endowing the material with higher initial capacity, improved rate performance, and superior cycling stability. Furthermore, this work establishes a clear correlation between the lattice parameters of the LRMO material and its Li⁺ transport and storage properties. These findings offer valuable mechanistic insights and a practical synthesis strategy for enhancing the electrochemical performance of LRMO cathodes by precisely controlling precursor crystallization and microstructure.