Effect of impeller design on the properties of Li_1.03Ni_0.8Mn_0.1Co_0.1O₂ cathode material synthesized via co-precipitation method

Li_1.03Ni_0.8Mn_0.1Co_0.1O₂ (NMC811) is the most promising composition for lithium-ion battery cathodes due to its low cobalt content and high capacity. The most widely used method to synthesize NMC811 is co-precipitation. Even though the co-precipitation process requires great control over each parameter, research that sheds light on the effect of impeller types on the electrode material's electrochemical performances is very limited. In this study, computational fluid dynamic (CFD) simulations for different types of impellers (pitched blade, hydrofoil blade, propeller, and Rushton turbine) were carried out using the Taguchi L4 array. The impellers were 3D printed, and the precursors (Ni_0.8Mn_0.1Co_0.1(OH)₂) were synthesized by utilizing those printed impellers. Simulations were used to gain insight into how impeller type affects the flow pattern, hence the final electrochemical performance of NMC811. The best cycle performance was obtained when a propeller-type impeller was used in coprecipitation. It delivered a discharge capacity of 174.58 mAh/g at a C/20 rate, with a coulombic efficiency of 96.02%. On the other hand, the Rushton turbine yielded the worst initial discharge capacity of 100.12 mAh/g at a C/20 rate. This significant difference proves that impeller geometry affecting the flow pattern strongly influences the electrochemical performance of the cathode.