Growth mechanism of Ni0.3Mn0.7CO3 precursor for high capacity Li-ion battery cathodes

Transition metal carbonate (Ni0.3Mn0.7CO3) was co-precipitated as the precursor for Li- and Mn-enriched composite materials used as advanced cathodes for lithium-ion batteries. The optimal pH range for synthesis of Ni0.3Mn0.7CO3 in a continuous stirred tank reactor (CSTR) at the pilot scale was predicted by taking into account the chemical equilibriums between the products and reactants. The nucleation and growth of precursor particles were investigated during the CSTR process by monitoring particle size distributions, particle morphologies, chemical compositions, and structures with time. It was found that in the early stage of co-precipitation both the particle size distribution and the chemical composition were not homogeneous; a lead time of about 5 hours under our experiment conditions was necessary to achieve the uniformity in particle shape and chemical composition. The latter was not altered during extended times of co-precipitation; however, a continuous growth of particles resulted in relatively large particles (D50 > 30 μm). The electrochemical performance of the final lithiated cathode materials is reported.