Enhanced reversible sodium storage performance in CoFe2O4 nanoparticles as an anode material for sodium-ion batteries

Sodium (Na)-ion batteries are being pursued as viable alternatives to lithium (Li)-ion batteries because of their reasonable cost and enormous potential in application scale-up for energy storage systems in the future. However, it is difficult to identify electrode materials capable of accommodating the large ionic radius of Na-ions which makes Na-ion batteries exhibit slower intercalation kinetics than Li-ion batteries. Spinel ferrite is of interest because of its high theoretical capacity derived from multiple oxidation states. Herein, CoFe2O4 nanoparticles were successfully prepared using the ball milling technique, followed by calcination at 700 degrees C and 800 degrees C with varying calcination time. CoFe2O4 calcined at 700 degrees C for 2 h exhibited a uniform distribution of small particles (0.12 mu m) and crystallites (45.89 nm). The electrode possesses high reversible capacity (178 mAh g(-1) at 0.1 C rate), reasonable cyclability (140 mAh g(-1) after 100 cycles) with 79% capacitive retention. The enhanced electrochemical performance of the CoFe2O4 electrode may be ascribed to its homogeneous distribution and fine particle size, which in turn decrease the Na-ion pathway and accelerate Na-ion transport within the electrode material.