Supercapacitor performance for ZnCo-MOF-74-derived nanospheres ZnO/ZnCo2O4
The unique structural properties of bimetal MOF-74 are one of the ideal precursors for building porous materials.ZnCo-MOF-74 is used as a precursor to prepare derivative ZnO/ZnCo2O4 nanospheres by high-temperature calcination method,its structure and morphology are analyzed.The electrochemical performance is tested in a three-electrode system with 6 mol/L KOH solution.The specific capacitance of ZnO/ZnCo2O4 is 1 047.8 F/g with n(Zn)∶n(Co)=1∶1 at a current of 1.0 A/g,which is larger than those of the mixed metal oxides obtained at other ratios.The high specific capacitance and good rate capability of ZnO/ZnCo2O4 are attributed to large specific surface area and the synergistic effect of the bimetal.The asymmetric supercapacitor is prepared with ZnO/ZnCo2O4 as the cathode material and activated carbon as the anode material,it has a specific capacitance of 74.3 F/g at 0.5 A/g.The corresponding specific energy density is 26.4 W·h/kg at a specific power of 536.3 W/kg.After 2 000 cycles at a current of 10.0 A/g in 0-1.6 V,the capacitance retention ratio is 81.3％.
transition metal oxides(TMOs)ZnO/ZnCo2O4metal organic frameworks(MOFs)electrode materialsupercapacitor
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