Hydrothermal Synthesis And Their Properties Of ZnCo₂O₄ Nanocomposite Electrode Materials

Nowadays,it is very important to develop emerging sustainable energy resource with increasing energy demands.Supercapacitors have attracted much attention due to their fast charge-discharge and high-power density.Transition metal oxides have obtained increasing attention in the field of supercapacitors due to their unique structural features.However,most transition metal oxides suffer from structural collapse during charge/discharge processes,which results in reducing of the cycle performance.Therefore,designing and fabricating electrode materials with high activity is essential to fabricate high performance device.ZnCo₂O₄nanomaterials is acted as the research object,this paper systematically studies the synthesis conditions of ZnCo₂O₄ and its complexes and the relationship between morphology and properformancs.The main contents are as follows:ZnCo₂O₄ nanorod electrode materials grown on nickel foam are obtained by a one-step hydrothermal method.The electrochemical performance of the samples is firstly studied via three-electrode tests,and the results show that the specific capacitance of the as-fabricated samples is 455.8 C g^-1.Meanwhile,the energy density of the assembled device is 0.14 Wh cm^-3,which corresponds to a power density of 4.1 W cm^-3,and its capacity retention rate is 78.75%after 10000 cycles.Heterostructured ZnCo₂O₄@Ni（OH）₂ electrode material is prepared by a two-step hydrothermal reaction.Firstly,ZnCo₂O₄ nanowires is fabricated on the surface of nickel foam,and then a layer of Ni（OH）₂ nanosheets is grown on the surface of the ZnCo₂O₄ nanowires.The prepared sample shows the high specific capacitance of 848.6 C g^-1 at a current density of 1 A g^-1.When is ulited to the positive electrode,and the activate carbon as the negative electrode to assemble the device,which presents a power density of 4675.3 W kg^-1at energy density of 57.3Wh kg^-1.ZnCo₂O₄@Ni-Co-S nanowires are prepared by hydrothermal and electrochemical deposition methods.Benefiting from the high electrical conductivity of sulfides and the synergistic effect between different materials,the specific capacitance of the synthesized ZnCo₂O₄@Ni-Co-S-9 sample is 1396.9 C g^-1 at 1 A g^-1.The device is assembled using the prepared sample as the positive electrode and activated carbon as the negative electrode.The test results show that the as-assembled device possess high energy density and superior cycle stability.