The Synthesis Of ZnCo₂O₄/carbon Material Composites And Their Application In Supercapacitor

As we all know, energy is the foundation of social development, the combustion of fossil fuels brings severe contamination to the environment at the same time as it brings brand new and rapid expansion to the industry and technology field. The energy and environment problem are becoming increasingly acute in 21 st century, in the rapid developing new century, the seek of more clean and efficient new energy to reassignment energy utilization patterns is urgent. We are aimed at exploiting an enviromental-friendly energy that can satisfy the reuirements of social development and bring no harm to the environment as well. The supercapacitor, as a brand new energy storage device, possess many excellent properties, such as long cycle life, high specific capacitance, large watt density, fast charge-discharge rate and environmental-friendly, has received extensive attention. In which the electrode materials are the major influence infectors affect the electrochemical performance of the supercapacitor, have also draw mass researchers’ attention. Zinc cobalt（ZnCo₂O₄）has unique pore structure, biggish specific surface, favourable electrical conductivity and theroy specific capacity, these peculiarities make it a very promising electrode active material using at supercapacitor. But like everything has its limits, the singular ZnCo₂O₄ electrode material has not much high energy density and can not provide higher specific capacity, so compositing with materials with good electric conductivity or high energy density has become hotspot in reforming the performance of singular ZnCo₂O₄ electrode material in these days. In this paper, we primary composit the ZnCo₂O₄ material with hydrothermal carbon（C）, reduced graphene oxide（r GO） and graphite carbon nitride（g-C₃N₄）, the morphology and structure of the composite materials were characterized and analysised with accordingly methods,the electrochemical performances were also studied.（1）The preparation of porous ZnCo₂O₄ electrode active materials using hydrothermal method, the qualitative and electrochemical analysis of the materials were also carried out. As it shows, porous ZnCo₂O₄ have loose and porous mophology,together with a big specific surface area, making it favorable for the transportation of the ionic and thus show good electrical conductivity, the electrode active materials bear excellent eclectrochemical and capacitive properities. The structure and morphology of the as-perpared materials were characterized by X-ray powder crystal diffraction（XRD）, transmission electron microscope（TEM）, scanning electron microscope（SEM）, fourier transforomed infrared（FTIR）, N₂ adsorption-disorption isothermal curve（BET） methods. The electrochemical and battery life tests were carried on electrochemical workstation testing system and the bule electric testing system. It was reveald that the materials’ capacitance remain 88.21% after 2000 circulation, the specific capacitance reach 600 F/g at the current density of 2 A/g, the electrode materials showe great cycling stability. As it has spherical and porous morphology, ZnCo₂O₄ can act as ligand compositing with other materials to synthesize electrode materials with superior electrochemical properities.（2）The preparation of spherical ZnCo₂O₄/C composites of porous ZnCo₂O₄in-situ grow on the surface of hydrothermal carbon sphere using hydrothermal method.The structure and morphology of the as-perpared materials were characterized by X-ray powder crystal diffraction（XRD）, transmission electron microscope（TEM）,scanning electron microscope（SEM）, fourier transforomed infrared（FTIR）, N₂adsorption-disorption isothermal curve（BET） methods. The electrochemical and battery life tests were carried on electrochemical workstation testing system and the bule electric testing system. It was reveald that ZnCo₂O₄ have successfully grew on the surface of carbon spheres, covered its surface, infinite enlarged the specific surface area of ZnCo₂O₄/C composite materials, provided more transmission path for the electrolyte ions, accelerated the process of the redox reaction and improved the specific capacitance, made the electrode material exhibit excellent electrochemical and capacitive performances. It was reveald that the materials’ capacitance remain77.71% after 5000 circulation, the specific capacitance reach 888F/g at the current density of 2A/g, the electrode materials showe great cycling stability. Compared with the bare ZnCo₂O₄ electrode materials, the properities of the composite materials have improved much a lot.（3）The preparation of spherical ZnCo₂O₄/r GO composites of porous ZnCo₂O₄in-situ grow on the surface of three-dimensional structured reduced graphene oxide using hydrothermal method. The structure and morphology of the as-perpared materials were characterized by X-ray powder crystal diffraction（XRD）, transmission electron microscope（TEM）, scanning electron microscope（SEM）, fourier transforomed infrared（FTIR）, N₂ adsorption-disorption isothermal curve（BET）methods. The electrochemical and battery life tests were carried on electrochemical workstation testing system and the bule electric testing system. It was reveald that ZnCo₂O₄ have successfully grew on the surface of reduced graphene oxide, covered its surface, infinite enlarged the specific surface area of ZnCo₂O₄/r GO composite materials, provided more transmission path for the electrolyte ions, accelerated the process of the redox reaction and improved the specific capacitance, magnified the coulombic efficiency and made the electrode material exhibit excellent electrochemical and capacitive performances. It was reveald that the materials’ capacitance remain 88.21% after 2000 circulation, the specific capacitance reach 1113F/g at the current density of 2A/g, the electrode materials showe great cycling stability.Compared with the bare ZnCo₂O₄ electrode materials, the properities of the composite materials have improved significantly.（4）The preparation of spherical ZnCo₂O₄/g-C₃N₄ composites of porous ZnCo₂O₄in-situ grow on the surface of three-dimensional layered graphite carbon nitride using hydrothermal method. The structure and morphology of the as-perpared materials were characterized by X-ray powder crystal diffraction（XRD）, transmission electron microscope（TEM）, scanning electron microscope（SEM）, fourier transforomed infrared（FTIR）, N₂ adsorption-disorption isothermal curve（BET） methods. The electrochemical and battery life tests were carried on electrochemical workstation testing system of shanghai chenhua and the bule electric testing system. It was reveald that ZnCo₂O₄ have successfully grew on the surface of g-C₃N₄, covered its surface,infinitly enlarged the specific surface area of ZnCo₂O₄/g-C₃N₄ composite materials,provided more transmission path for the electrolyte ions, accelerated the process of the redox reaction and improved the specific capacitance, magnified the coulombic efficiency and made the electrode material exhibit excellent electrochemical and capacitive performances. It was reveald that the materials’ capacitance remain 85.35%after 5000 circulation, the specific capacitance reach 1128F/g at the current density of2A/g, the electrode materials showe great cycling stability. Compared with the bare ZnCo₂O₄ electrode materials, the properities of the composite materials have improved significantly, exhibit superior application in supercapacitors.