Insight into LaFeO3-Coating Effects on O3-Type NaNi1/3Fe1/3Mn1/3O2 Cathode Materials for Sodium-Ion Battery Application

Layered oxide O3 NaNi1/3Fe1/3Mn1/3O2 (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).