Preparation And Performance Of Metal Oxide/Carbon Composite On Nickel Foam Substrate As Electrode Materials

Electrochemical supercapacitors are energy storage devices that attracted muchattention due to their high power capability and long cycle life. However, as a newtype of energy storage devices, it is also facing some challenges, especially toimprove the energy density. In recent years, extensive work has focused on ways toenhance both the power and energy density of electrochemical capacitors. In order toachieve a reasonable balance between cost and performance of the electrode material,many researchers started to study on the development of composite materials, In thisthesis, a novel method on one-pot hydrothermal direct synthesis of NiO/C andMnO2/C composite microspheres on nickel foam has been reported; MnO2grown oncarbon/nickel foam by hydrothermal method and electrochemical deposition. Themain research and innovation are shown as follows：（1） In this thesis, NiO/C composite microspheres on nickel foam with glucose andNi（NO3）2as precursors have been prepared by one-pot hydrothermal method. Theproduct presents a spherical morphology with the carbon component in the compositebeing a non-graphitic phase. The presence of NiO provides additionpseudo-capacitance for the electrode materials and the composites exhibit superiorspecific capacitance to the pure carbon materials formed on the nickel foam.Comparing with the nickel sheet substrate, the utilization of the nickel foam benefitsfor the achievement of higher performance and stability owing to its unique3Dstructure. The highest specific capacitance for the NiO/C/nickel foam electrode of265.3F·g^-1is obtained at a discharge current density of0.25A·g^-1.（2） Using glucose and MnSO4as precursors, the manganese bioxide/carbon（MnO2/C） composites are directly formed on the nickel foam by one-pot hydrothermal method. The effect on the morphology of the material with differentconcentration of reactants, molar ratio, reaction temperature and time have beenstudied. The advantages of this preparation method is to facilitate the direct study ofits electrochemical properties, the post-processing such as tabletting process notrequired in this method. The product structure, surface morphology andelectrochemical properties were evaluated. At a current density of5A·g^-1, themaximum capacity of MnO2/C/nickel foam is702F·g^-1, and it has goodelectrochemical performance and cycle stability.（3） Using MnSO4and Na2SO4as precursors, petal-like manganese dioxideelectrode materials were successfully prepared on the nickel foam substrate withdifferent method: hydrothermal method and anodic electrodeposition. The influenceof different reaction parameters on the experimental results, the reaction parameters,including the quality of the electrochemical deposition, electrochemical depositionpotential and electrolyte concentration also been investigated. From the experimentalcomparison, the optimal experimental conditions: deposition voltage of1.1V, theelectrolyte concentration is0.04mol·L^-1, electrodeposition, the electrode materialhave better electrochemical performance. The results showed that: the MnO2/C/nickelfoam electrode material in the current density (1.5A·g^-1,), up to1045.5F·g^-1specificcapacity. It is indicating the electrode materials with good electrochemicalperformance and cycle stability.