| With the rapid development of the global economy,the development of human society is more and more inseparable from the dependence on energy,especially in the demand for fossil energy.Supercapacitors,as a new type of energy storage device between traditional capacitors and batteries,have attracted much attention in many fields such as mobile communications,electronics,aerospace and many other fields due to their advantages such as high power density,long cycle life and high current charge and discharge characteristics.The production and consumption of fossil energy is the main cause of severe global climate,serious environmental pollution and ecological damage.Therefore,the development and utilization of efficient,clean and sustainable renewable energy and new energy conversion and storage technology has triggered a worldwide research boom.Electrode materials play an irreplaceable role in the components of supercapacitors.Therefore,the study of electrode materials for supercapacitors plays an important role in the development of supercapacitors.In this thesis,the electrode materials are prepared by using low cost porous carbon materials and copper foam as conductive substrates and mixed with transition metal oxides or hydroxides to improve the conductivity,cycle stability,specific capacitance and rate performance of the electrode materials by means of scanning electron microscopy,transmission electron microscopy and cyclic voltammetry.The surface morphology,crystal structure and electrochemical properties of electrode materials are investigated by constant current charge-discharge method.The contents of the study are as follows:1.On the surface of porous carbon materials,a uniform layer of MnO2 nanostructures is grown by hydrothermal method.The porous carbon material has the structure of continuous large pore channel,which is not only conducive to the rapid transmission of electrons,but also to facilitate the loading of active materials,and to accelerate the penetration of ions in electrolyte.On the other hand,the high theoretical capacity of MnO2 makes the prepared MnO2 porous carbon electrode materials have better electrochemical performance.The results show that when the current density is 1 A g-1,the specific capacitance of electrode material reaches 386F g-1,and the cycle capacity of 5000 cycles is 84%,which shows its excellent cycle stability.2.The copper foam as substrate by surface oxidation on the surface of the uniform growth of a layer of Cu(OH)2 nanowires by chemical etching,the Cu(OH)2 nanowire surface becomes rough and porous,increasing its surface area.Then by the method of electro deposition,in copper foam the substrate in situ growth of cobalt nickel nano film structure of double hydroxides(LDH)composite material.By means of SEM and TEM,it was found that LDH was tightly wrapped in Cu(OH)2 nanowires.The Cu(OH)2 nanowires are arranged closely on the copper foam substrate,showing a dense three-dimensional core-shell structure.The core-shell structure can increase a large number of reaction sites to produce redox reactions to improve the specific capacitance of the electrode material,which can be increased to 6.8 F cm-2 at the current density of 5 mA cm 2.The asymmetric capacitor composed of eCu(OH)2@NixCo2x(OH)6x composite electrode and activated carbon electrode has an energy density of 1.83 mWh cm-3 at the power density of 200 mW cm-3,and has excellent cyclic stability.And the red LED has been illuminated successfully,which shows that the electrode material has potential use value in human life. |
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