Facile synthesis of hollow urchin-like NiCo2O4 microspheres for high-performance sodium-ion batteries

Hollow urchin-like NiCo 2 O 4 microspheres were facilely synthesized by a simple hydrothermal approach combined with subsequent annealing process. The three-dimensional architectures with hollow structure are formed by the mechanism of the nanowires self-assembly associate with the subsequent Ostwald ripening process. The as-obtained NiCo 2 O 4 microspheres with the average diameter of about 5 μm consist of numerous radial nanowires and benefited from the hollow urchin-like microsphere structure, Brunauer–Emmett–Teller results show that it possesses a large specific surface area of 92.8 m 2 g −1 , when it was applied as an electrode material for sodium-ion batteries, the NiCo 2 O 4 electrode displayed a high invertible capacity of ~440 mAh g −1 after 200 cycles at a current density of 100 mA g −1 , and the electrochemical measurement results also indicated the NiCo 2 O 4 electrode possess a charming rate capability. These results suggest a promising application of the hollow urchin-like NiCo 2 O 4 microspheres for the advanced sodium-ion batteries.