Electrochemical performance and thermal stability of Co3O4 modified high nickel ternary cathode materials

Abstract

LiNi_xCo_yMn_1-x-yO₂ (NCM, x > 0.6) is a high-nickel ternary cathode material extensively utilized in the renewable energy sector due to its cost-effectiveness and high energy density. Nonetheless, its utilization is constrained by structural instability, interfacial side reactions, and thermal safety concerns. This investigation involved the application of varying concentrations of Co₃O₄ onto the surface of NCM for modification purposes. The influence of coating quantity on the thermal safety and electrochemical performance of the material was examined in conjunction with morphological characterization, electrochemical testing, and thermal safety assessment. The findings indicate that Co₃O₄ coating acts as a physical barrier to isolate NCM from the electrolyte, diminish lithium-nickel intermixing, and improve the structural stability of the material. Electrochemical tests revealed that the 1 % Co₃O₄-coated NCM delivered superior cycling stability. After 200 cycles at 0.2C, the capacity retention rate reached 82.85 %, which was 16 % higher than the pristine NCM (66.85 %), and the discharge specific capacity at 3C is 133.3 mAh/g. Thermal analysis results indicate that Co₃O₄ coating increases the initial temperature of thermal runaway in NCM material. In summary, a modest Co₃O₄ coating can synergistically optimize the electrochemical performance and safety of high nickel ternary NCM materials by refining surface structure, promoting interface charge transmission, and improving thermal stability.