Insight into LaFeO₃-Coating Effects on O3-Type NaNi_1/3Fe_1/3Mn_1/3O₂ Cathode Materials for Sodium-Ion Battery Application

Layered oxide O3 NaNi_1/3Fe_1/3Mn_1/3O₂ (NFM) is a good material to use for the cathode of sodium-ion batteries. Nevertheless, side reactions between the active material and electrolyte may cause cycling instability, which limits its practical application. Herein, we coated LaFeO₃ onto the surface of NFM using a wet chemical method. LaFeO₃ develops a shielding layer on the NFM’s surface owing to its outstanding thermal and chemical stability. Meanwhile, the inherent oxygen absorption capability of LaFeO₃ induces the formation of an appropriate amount of oxygen vacancies within the NFM, facilitating the reduction of Mn⁴⁺ and increasing the Mn³⁺ concentration. Of all the samples, the 2.0 wt % LaFeO₃-coated NFM shows enhanced rate performance and cycling stability. The capacity retention is 76.61% at 1C after 100 cycles, which is far superior to that of the 60.91% retention observed for the pristine NFM. Furthermore, at a high rate of 5C, the 2.0 wt % coated cathode exhibits superior rate capability (103.4 mAh·g^-1), outperforming the pristine cathode (90.8 mAh·g^-1).