Fabrication And Electrochemical Properties Of Flexible Metal Oxide/Carbon Electrode Materials

With the continuous growth of energy consumption,the available fossil energy is increasingly depleted.The development and utilization of fossil energy result in serious environmental pollution and ecological damage,which forces us to change the current energy consumption patterns and look for renewable clean energy.Among various new and efficient energy storage materials,supercapacitor electrode materials have received intense attention due to their unique characterics.Recently,the appearance and rapid development of wearable and flexible devices raise high demand for the electrochemical capacitors and their corresponding electrode materials.Hence it is very important to develop the flexible supercapacitors and electrode materials.In this thesis,carbon cloth with high conductivity was used as the flexible electrode substrate.Some high-performance carbon cloth-based electrode materials were designed and prepared by controlled depositing double electric layer and pseudocapacitance materials on the fiber surface inside carbon cloth.The specific research contents are as follows:?1?A flexible nickel oxide/carbon cloth?NiO/CC?electrode material was prepared by the hydrothermal synthesis and thermal decomposition methods.A layer of porous nickel oxide nanowire arrays was deposited on the carbon fiber surface inside carbon cloth.?2?A three-dimensional?3D?NiCo₂O₄/carbon nanotubes/carbon cloth?Ni Co₂O₄/CNTs/CC?electrode material was prepared.ZnO nanorod arrays on the carbon fiber surface were used as the template to generate the carbon nanotubes.The carbon nanotubes/carbon cloth provides a conductive network for the fast electrontransportation.After growing ultrathin and porous NiCo₂O₄ nanosheets on the carbon nanotubes,the resultant Ni Co₂O₄/CNTs/CC electrode material was used in supercapacitors.?3?The morphologies and microstructures of carbon cloth-based electrode materials were characterized by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,X-ray diffraction?XRD?and X-ray photoelectron spectroscopy?XPS?.The electrochemical performance of the solution was measured by cyclic voltammetry and constant current charge-discharge methods in KOH electrolyte solution.The influences of mechanical bending,stretching and twisting on the electrochemical performances of the electrode materials were also evaluated.The results show that the NiO/CC electrode material reached a maximum specific capacitance of 652 F/g at a scan rate of 2 m V/s.Its specific capacitance retention value was 92% after 10000 cycles at a current density of 13.7 A/g.The highest specific capacitance of Ni Co₂O₄/CNTs/CC was determined to be 1518 F/g at a scan rate of 5 m V/s.After 3000 cycles at the current density of 10 A/g,the specific capacitance retention value was over 88%.Moreover,both electrode materials show stable performances under the mechanical bending,stretching and twisting conditions.