Microwave Synthesis Of Electrodes Based On Nickel Foam For High-performance Supercapacitors

With the rapid developments of economic society and the rise in population,the energy resources utilized effectively is declining and the ecological environment is worsening continuously.Accordingly,it will be necessary to build a carbon-reducing society which is supported by the renewable energy in the near future.Electrochemical supercapacitors,as a novel power devices,are very attractive as an energy storage device since its quick charge–discharge rate,maintenance-free long-life operation,and environmentally friendly.However,the advantages and disadvantages of supercapacitors depend greatly on the performance of electrode materials.Therefore,it is one of the hot spots in the current research to find a better electrode material for supercapacitors.In this paper,we synthesised different electrode materials in a simple and cost-effective microwave method using Ni foam as substrate,including conducting polymer/graphene,metallic oxide/graphene and metal oxide composited on the pro-treated Ni foam.The main points of this paper are summarized as follows:1.Nanoflower-like MnO₂/Ni?OH?₂composite was successfully prepared with a simple microwave method.The structure characterization and surface morphology were investigated using FT-IR,Raman spectroscopy,scanning electron microscopy?SEM?,and X-ray diffraction?XRD?.The electrochemical performances were investigated by cyclic voltammetry,electrochemical impedance spectroscopy and constant current charge/discharge techniques.The results indicate that the specific capacitance of the MnO₂/Ni?OH?₂/NF electrode are 506,436,401,387,373,358,357 and 344 F/g under high current density 16.7,18.3,20.0,21.7,23.3,25,26.7 and 28.3 A/g,respectively.And there is about 96%of the maximum specific capacitance remained after finishing 7000 cycles,suggesting a promising candidate for high-performance supercapacitors.2.3-D honeycomb-like PANI/rGO/Ni?OH?₂composite was successfully prepared with microwave-hydrothermal-solution method.The structure characterization and surface morphology were investigated using FT-IR,Raman spectroscopy,scanning electron microscopy?SEM?,and X-ray diffraction?XRD?.The effects of different monomer on the performance of the electrode materials were examined and the experimental conditions were optimized.The electrochemical performances were investigated by cyclic voltammetry,electrochemical impedance spectroscopy and constant current charge/discharge techniques.The results indicate that the specific capacitance of the PANI/rGO/Ni?OH?₂/NF electrode are382.5,375.75,356.25,341.3 and 312.75 F/g under current density at 15,16.7,25,33.3,41.7and 28.3 A/g,respectively.3.A flexible PANI/MnO₂/Ni?OH?₂composite was successfully prepared though the combination of microwave,ultrasonic and solution method.The structure characterization and surface morphology were investigated using FT-IR,Raman spectroscopy,scanning electron microscopy?SEM?,and X-ray diffraction?XRD?.The electrochemical performances were investigated by cyclic voltammetry,electrochemical impedance spectroscopy and constant current charge/discharge techniques.The results indicate that the specific capacitance of the PANI/MnO₂/Ni?OH?₂/NF electrode are 214,206,128,124,105,and 104 F/g at 1.4,1.8,2.3,3.6,4.5,and 5.5 A/g,respectively.There is about 92%of the maximum specific capacitance remained after finishing 7000 cycles.4.Needle-like MnO₂/rGO/Ni?OH?₂composite was successfully prepared though the combination of microwave and hydrothermal.The structure characterization and surface morphology were investigated using FT-IR,Raman spectroscopy,scanning electron microscopy?SEM?,and X-ray diffraction?XRD?.The electrochemical performances were investigated by cyclic voltammetry,electrochemical impedance spectroscopy and constant current charge/discharge techniques.Results indicate that the specific capacitance of the MnO₂/rGO/Ni?OH?₂/NF electrode at 11.57 and 30.7 A/g are 324.3 and 245.6 F/g respectively,which also exhibits long-term electrochemical stability with a capacitance retention of 80%after 8000 cycles.Furthermore,the as-prepared MnO₂/rGO/Ni?OH?₂/NF was used for H₂O₂ sensors,which exhibit high performance with a low detection limit of 0.058?M.