Excellent Electrochemical Performance and Air Storage Stability of Na-Ion Layered Oxide Cathodes Benefiting from Enhanced Ce–O Binding Energy

The widespread application of layered oxides is constrained by their low electrochemical performance and complex irreversible phase transition. The high entropy oxide NaNi_0.25Fe_0.15Mn_0.3Ti_0.1Sn_0.05Co_0.05Li_0.1O₂ (HEO) is synthesized by leveraging the entropy stabilization effect, which offers a partial solution to this issue, but electrochemical performance and air stability imperative to be improved. On the high entropy oxide HEO, due to the strong bond energy of Ce-O, the introduction of Ce⁴⁺ improves the specific discharge capacity and reduces the battery gas production problem. It also improves the air stability. NaNi_0.25Fe_0.15Mn_0.3Ti_0.1Sn_0.03Ce_0.02Co_0.05Li_0.1O₂ (HEO-Ce2) demonstrated a specific discharge capacity of 160 mA h g^-1 at 0.1 C. The discharge-specific capacity retention rate of the material is 86%, after air exposure for 10 days. The high entropy effect and introduction of Ce⁴⁺ provide a viewpoint for a layered oxide of sodium-ion batteries.