Investigation of structure and cycling performance of Nb-doped nickel-rich single-crystal ternary cathode materials

Ni-Co-Mn (NCM) ternary cathode material has developed rapidly in the electric vehicle industry due to its quite low price and high-energy density. However, its practical application is limited due to serious electrochemical performance degradation and thermal instability in long-term cycle. To address such issues, Nb doping nickel-rich monocrystal NCM ternary cathode material was put forward. Because of the smooth surface and uniform size of single-crystal particles, the Li+ transmission capacity is improved, and the internal Nb doping enhances the stability of crystal structure and reduces the cation mixing of materials. Therefore, the cycle stability and rate performance of the material are greatly improved. Impressively, through the modification of the Nb element at the optimum temperature of 900 ℃, the capacity retention rate of the battery is as high as 99.3% for 100 cycles and 93.7% for 200 cycles at rate of 1 C. The specific discharge capacity at the 5C rate reached 155.5 mAh/g. This result is promising for long cycle applications. The material has excellent cycle stability due to its stable crystal structure.