Stepwise co-precipitation to the synthesis of urchin-like NiCo2O4 hollow nanospheres as high performance anode material

Abstract

Hierarchical hollow structures are of great interest as electrode materials for lithium ion batteries. They can provide enlarged surface area for efficient contact between electrode and electrolyte, endow the electrodes with fast electron and ion transfer and accommodate the volume change resulted from charge/discharge cycling. Herein, we report the synthesis of urchin-like NiCo2O4 hollow nanospheres based on a special stepwise co-precipitation method. The hollow nanostructures result from the non-equilibrium mass diffusion induced by a rationally designed stepwise co-precipitation reaction. Owning to the hierarchical hollow architectures, the as-prepared urchin-like NiCo2O4 hollow nanospheres exhibit excellent electrochemical properties as anode materials for lithium-ion batteries, with a large discharge capacity of 1232.3 mAh/g at 0.1 C, a high initial coulombic efficiency of 78.4% and a high capacity retention of 95.6% at 0.5 C after 100 cycles. Based on a special stepwise co-precipitation method, we have successfully synthesized hierarchical hollow urchin-like NiCo2O4 nanospheres as anode material caused by cross-layer non-equilibrium diffusion. The unique hierarchical hollow structure can provide efficient electrode–electrolyte contact and endow the electrodes with fast electron and ion transfer enhancing the rate performance of the anode material. Also, the hollow structure can suppress the volume change during the repeated Li+ insertion/extraction in the host corresponding to the enhanced cycling performance.