Multishelled Ni_x Co_3-x O₄ Hollow Microspheres Derived from Bimetal-Organic Frameworks as Anode Materials for...

Metal-organic frameworks (MOFs) featuring versatile topological architectures are considered to be efficient self-sacrificial templates to achieve mesoporous nanostructured materials. A facile and cost-efficient strategy is developed to scalably fabricate binary metal oxides with complex hollow interior structures and tunable compositions. Bimetal-organic frameworks of Ni-Co-BTC solid microspheres with diverse Ni/Co ratios are readily prepared by solvothermal method to induce the Ni _x Co_3-x O₄ multishelled hollow microspheres through a morphology-inherited annealing treatment. The obtained mixed metal oxides are demonstrated to be composed of nanometer-sized subunits in the shells and large void spaces left between adjacent shells. When evaluated as anode materials for lithium-ion batteries, Ni _x Co_3-x O₄ -0.1 multishelled hollow microspheres deliver a high reversible capacity of 1109.8 mAh g^-1 after 100 cycles at a current density of 100 mA g^-1 with an excellent high-rate capability. Appropriate capacities of 832 and 673 mAh g^-1 could also be retained after 300 cycles at large currents of 1 and 2 A g^-1 , respectively. These prominent electrochemical properties raise a concept of synthesizing MOFs-derived mixed metal oxides with multishelled hollow structures for progressive lithium-ion batteries.