Construction of Zinc MOFs-Derived Carbon-Based Zn-Co Oxides Porous Nanocages and Their Application as Electrodes for Electrochemical Energy Storage

Metal-Organic frameworks (MOFs) and their derivatives have been widely used in lithium-ion batteries (LIBs) since their introduction because of their high porosity, large specific surface area, and structural and functional versatility. In this paper, the Zn-Co MOF-derived nanocages oxides with porous channel-crossing structure were successfully prepared by a low-temperature calcination self-assembly strategy. As anode of LIBs, the reduced graphene oxide (RGO)/ZnO/Co3O4 has excellent rating and cycling performances compared to the RGO/Co3O4. The RGO/ZnO/Co3O4 electrode maintains a reversible capacity of about 900 mAh g-1 after 500 cycles, which is 1.5 times higher than that of the RGO/Co3O4 electrode. At high current density of 2 A g-1, the discharge specific capacity of RGO/ZnO/Co3O4 is 500 mAh g-1, which is 1.25 times that of RGO/Co3O4. The superior electrochemical performance is attributed to its specific three-dimensional porous channel structure and internal Zn/Co oxide semiconductor heterointerface structure, which increases the effective active area of the electrode, improves the storage capacity and carrier transport efficiency of Li+, and enhances the overall structural stability as well as electrochemical activity. In addition, the improved electrochemical performance cannot be achieved without the synergistic effect of ZnO and Co3O4.