Environmental and health concerns, alongside their non-renewability, drive the need to reduce the usage of fossil fuels as an energy source. One approach is the replacement of internal combustion engine vehicles with battery electric vehicles (BEVs), which can reduce both environmental and health-related pollution. However, the widespread adoption of BEVs requires improvements in battery chemistries. One of the most promising cathodes for BEVs is LiNi0.8Mn0.1Co0.1O2 (NMC(O2)-811), which, despite stability issues, is projected to dominate in the coming decades. The performance of these cathode materials is directly linked to their particulate properties, making control over synthesis critical for optimising battery performance.
This thesis investigates the coprecipitation reaction used to produce the (NMC(O2)-811) precursor Ni0.8Mn0.1Co0.1(OH)2, which lacks fundamental understanding at the particulate level. Through a combined experimental and chemical equilibrium modelling approach, this investigation aims to clarify the particle formation mechanisms in the coprecipitation process and their sensitivity to variations in process parameters.
The chemical speciation modelling aligns with previous studies, showing increased transition metal solubility at lower pH and higher NH3 concentrations. Experimental validation of this modelling approach, presented here for the first time, highlights the need for a closer examination of the thermodynamic parameters driving these models due to discrepancies between experimental and modelled solubilities. Dynamic image analysis, a novel quantitative shape analysis method for this system, showed an increase in Ni0.8Mn0.1Co0.1(OH)2 circularity from 0.65 to 0.81 with changes in process parameters. Particle size analysis as a function of process parameters exhibited a parabolic response, increasing from 5.37 μm to 17.1 μm before decreasing to 12.8 μm at 0.3 M, 0.9 M, and 1.5 M NH3, respectively. Global correlation analysis revealed a statistically significant correlation (ρc = 0.80) between nickel solubility and tap density, marking one of the first statistical studies linking process conditions to particulate properties in this system.
