Two-dimensional porous nanodisks of NiCo2O4 as anode material for high-performance rechargeable lithium-ion battery

Abstract

Two-dimensional porous nanodisks of NiCo2O4 have been synthesized by low temperature hydrothermal method followed by calcination at 500 °C/3 h/air. X-ray diffraction pattern confirmed the phase purity of the sample. Microstructure analysis clearly exhibits a unique porous nanodisks shape of NiCo2O4 sample. Brunauer–Emmett–Teller technique is also used to investigate the surface area and pore size of the sample. Electrochemical properties are evaluated via cyclic voltammetry and Galvanostatic cycling studies. NiCo2O4 as an anode exhibits excellent lithium storage capacity (673.9 mAh g−1 at 0.5C after 350 cycles; 596.9 mAh g−1 at 3.0 C after 200 cycles), high initial Coulombic efficiency (75%), long cycling stability (∼80% capacity retention at 350 cycles) and better rate capability (552.5 mAh g−1at 4.0 C), which is much higher than the theoretical capacity of graphite (372 mAh g−1). This improvement can be attributed to the unique porous structure of the electrode, which allows maximum Li+ ion to react with electrode material, shortens the diffusion path length and increasing the electrode/electrolyte contact area.