High Electrochemical Performance of Monodisperse NiCo2O4Mesoporous Microspheres as an Anode Material for Li-Ion Batteries

Binary metal oxides have been regarded as ideal and potential anode materials, which can ameliorate and offset the electrochemical performance of the single metal oxides, such as reversible capacity, structural stability and electronic conductivity. In this work, monodisperse NiCo2O4 mesoporous microspheres are fabricated by a facile solvothermal method followed by pyrolysis of the Ni0.33Co0.67CO3 precursor. The Brunauer–Emmett–Teller (BET) surface area of NiCo2O4 mesoporous microspheres is determined to be about 40.58 m2 g–1 with dominant pore diameter of 14.5 nm and narrow size distribution of 10–20 nm. Our as-prepared NiCo2O4 products were evaluated as the anode material for the lithium-ion-battery (LIB) application. It is demonstrated that the special structural features of the NiCo2O4 microspheres including uniformity of the surface texture, the integrity and porosity exert significant effect on the electrochemical performances. The discharge capacity of NiCo2O4 microspheres could reach 1198 mA h g–1 after 30 discharge–charge cycles at a current density of 200 mA g–1. More importantly, when the current density increased to 800 mA·g–1, it can render reversible capacity of 705 mA h g–1 even after 500 cycles, indicating its potential applications for next-generation high power lithium ion batteries (LIBs). The superior battery performance is mainly attributed to the unique micro/nanostructure composed of interconnected NiCo2O4 nanocrystals, which provides good electrolyte diffusion and large electrode–electrolyte contact area, and meanwhile reduces volume change during charge/discharge process. The strategy is simple but very effective, and because of its versatility, it could be extended to other high-capacity metal oxide anode materials for LIBs.