Application of NiO-modified NiCo2O4 hollow spheres for high performance lithium ion batteries and supercapacitors

Abstract In this report, we synthesize a series of metal oxide hollow microspheres by adjusting the ratio of reactants, through a facial one-step hydrothermal treatment followed by annealing. The properties of as-prepared hollow microspheres are investigated to be applied as electrode for both lithium ion batteries (LIBs) and supercapacitors (SCs). The obtained NiCo2O4/NiO composite, with mesopores at the surface of hollow spheres, shows excellent electrochemical performances according to the cyclic voltammetry and impedance measurements. At a current density of 100 mA g−1, a large reversible capacity of 659 mAh g−1 was achieved for NiCo2O4/NiO after 100 cycles as the anode material of LIBs. As an electrode for SCs, NiCo2O4/NiO exhibits high electrochemical performances with a capacitance of 708.4 F g−1 at a current density of 1 A g−1 and a high retention about 94.3% after 10,000 cycles at 10 mA g−1. It was estimated to deliver a high energy density of 25.06 Wh kg−1 at a power density of 250 W kg−1 The outstanding electrochemical properties can be attributed to the synergistic effect of different metal oxides, and the special morphology of porous hollow microspheres, which has a high specific surface area to facilitate the soaking of electrolyte and fast Li+ diffusion, as well as offer accommodation for the volume change.