Stabilization of NCM811 cathode for Li-ion batteries by N-doped carbon coating

Ternary nickel-rich layered oxide LiNi0.8Co0.1Mn0.1O2 (NCM811), as a promising next-generation cathode material for lithium-ion batteries, is still suffered from severe capacity fading triggered by irreversible phase transition and side reactions during cycling, which can be effectively circumvented by surface coating. Herein, microspheric NCM811 particles are homogeneously coated by N-doped carbon layer via a facile and low-cost rheological phase reaction method followed by low temperature sintering. The N-doped carbon coating disperses more uniformly than carbon coating on NCM811, which is attributed to the formation of Ni-N bond between carbon coating layer and bulk NCM811. And the introduced N element can inhibit the reduction of Ni3+ to Ni2+ on the surface of NCM811, leading to a positive effect on the suppression of cationic mixing that further improves the structural stability. Based on the electrochemical performance analyses, it is found that the surface pseudocapacitance and Li+ diffusion ability both are significantly promoted after N-doped carbon coating. Benefit from the suitable pseudocapacitive behavior and high Li+ diffusion coefficient, the NCM811-CN0.5 electrode presents a discharge specific capacity of 216.98 mAh/g at 0.1C, 151.01 mAh/g at 10C, and capacity retention of 82.3 % after 500 cycles at 5C, indicating that it will be an ideal cathode material for developing highpower and long-lifespan lithium-ion batteries.

Automated summary

Surface coating with N-doped carbon layer can effectively improve the capacity fading issue of ternary nickel-rich layered oxide LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material for lithium-ion batteries. The N-doped carbon coating disperses more uniformly than carbon coating due to the formation of Ni-N bond. The introduced N element can inhibit the reduction of Ni3+ to Ni2+, leading to improved structural stability.