Effects of coating layer homogeneity of cathode particles on lithium ion battery performance

Ensuring the stability of cathodes under high voltage (>4.3 V vs. Li/Li + ) necessitates particle-scale surface protection. Research varies on the optimal structure, and systematic studies on the impact of nanoscale coating coverage on cathode particle surfaces and stability are lacking. This study presents a quantitative analysis of coating homogeneity dependency on cathode particles and their stability under high voltage conditions. A metal alkoxide precursor-based coating methodology was used, manipulating the coating structure by understanding the pH dependence of the zeta potential for core particles and altering the precursor evaporation rate. Ta-substituted Li₇La₃Zr₂O₁₂ was chosen as the coating material on Li(Ni_1/3,Co_1/3,Mn_1/3)O₂ cathode particles, varying the coating structure while maintaining the same coating concentration. Coating structure was verified using X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). Results showed that cathode particles with more homogeneous coatings exhibited significantly improved cycle stability and lower charge transfer resistance at potentials above 3.9 V. Optimizing coating homogeneity can significantly enhance battery performance, offering insights for more efficient lithium-ion batteries.