Ce ⁴⁺ Doping to Improve the Electrochemical Performance of NaNi _0.4 Fe _0.2 Mn _0.4 O ₂ Cathode Material

Sodium resources are significantly more abundant than lithium resources. Consequently, low-cost sodium-ion batteries have significant prospects for applications in the storage market. Owing to their high specific capacity and simple synthesis, layered transition metal oxides are among the most commercially viable cathode materials for sodium-ion batteries. In this study, Ce⁴⁺ doping at the transition metal site was investigated using density functional theory. The results indicate that the strong Ce─O bond energy can improve the structural stability of the cathode material. Moreover, Ce⁴⁺ doping can increase layer spacing and accelerate sodium-ion transport. The modified sample exhibited a specific discharge capacity of 91.4 mAh g^-1 at 5°C. After 100 cycles at 0.5°C, the capacity retention rate was 77.6%. Notably, the cycling and rate performances of the material improved. Thus, it provides a reference for developing high-performance cathode materials for sodium-ion batteries.