Computational Study of the Role of Spinel LiCo2O4 Coating Layer between Layered LiNi0.8Co0.15Al0.05O2 Cathode Material

Abstract

The internal coating of secondary particles of active material has been employed to enhance the electrochemical performance of Li-ion batteries. Especially, the glue-nanofiller layer, consisting of a spinel-like LixCoO2 (LCO) phase, was introduced between grains of the layered LiNi0.8Co0.15Al0.05O2 (NCA) cathode material to achieve outstanding capacity retention not only at room temperature and but also at 60°C. Herein, the role of the spinel-like LCO coating layer between NCA grains was explored by using the molecular dynamics (MD) simulations. The effect of voids on the interaction between primary particles was investigated and the binding energies of the NCA/NCA and NCA/LCO interfaces were predicted. From the MD simulations, it was revealed that the voids between the primary particles weakened the binding forces between the grains and the binding strengths of NCA/LCO interfaces were larger than those of NCA/NCA interfaces. The results indicated that the LCO coating layer could play the crucial role of glue between NCA particles by filling the voids with enhanced adhesion strength and improving the overall mechanical strength of secondary particles.