Efficient Preparation And Performance Of Electrode Material For Supercapacitor

Supercapacitors exhibit the superiority of high power density and excellent service life,so they have broad application prospects in cameras,railways,electric power and aerospace vehicles,and the energy storage in supercapacitors is mainly determined by the electrode materials.Based on the current research on electrode materials,traditional synthesis methods usually require complex devices,high temperature treatment long-term operation,and have the disadvantages of high cost or poor repeatability,and their application is limited due to the inability to industrialize production.Therefore,exploring economic,simple,reproducible and environmentally friendly methods for preparing electrode materials is an urgent goal to be achieved.In this paper,the simple water-boiling treatament and one-step pyrolysis method are used to prepare electrode materials,exhibiting high capacitance,excellent rate performance and cyclability.The main research contents are as follows:(1)Mn3O4/Ni(OH)2 nanocomposite was prepared at 100? by a simple water-boiling treatment.Compared to the composites undergoing water-boiling for 1.5 and 5 h,the composite treated for 3 h exhibited higher capacitance,superior rate performance and cyclability(the capacitance is 742 F/g at 1 A/g and 318 F/gat 8 A/g in 1 M KOH electrolyte,respectively;after 2000 cycles at 2 A/g,the capacitance retention is as high as 80%).The electrochemical properties of Mn3O4/Ni(OH)2 nanocomposites are significantly better than those of individual Mn3O4 and Ni(OH)2 prepared under the same conditions.When assembling asymmetric capacitor with the Mn3O4/Ni(OH)2 composite and activated carbon separately as positive and negative electrodes,the asymmetric capacitor reveled a energy density of 15.3 Wh/kg at a power density of 168.8 W/kg.The excellent electrochemical properties of Mn3O4/Ni(OH)2 nanocomposite is attributed to the mutual doping of Mn3+ in Ni(OH)2 and Ni2+in Mn3O4 to imrove the electronic conductivity.Therefore,This simple,reproducible,eco-friendly,and large-scale fabrication method is practically applicable for preparing other transition metal oxides for the purpose of utilization in the asymmetric supercapacitors with superior properties.(2)CuO/Ni(OH)2 nanocomposite was prepared by a simple water-boiling treatment under mild conditions of 100?.Compared with the composite materials with Cu and Ni atomic ratios of 1:0.75 and 0.75:1,the composite with atomic ratios of 1:1 prepared under the same conditions exhibits superior electrochemical performance.In a three-electrode cell with 1 M KOH as the electrolyte,the CuO/Ni(OH)2 nanocomposite displays a specific capacitance of 1248 F/g at 1 A/g and a capacitance retention of 86%after 6000 cycles at 2 A/g,obviously superior to the Mn3O4/Ni(OH)2 nanocomposite.Particularly,the asymmetric supercapacitor with the positive electrode of CuO/Ni(OH)2 nanocomposite and negative electrode of commercial activated carbon demonstrates an energy density of 18.9 Wh/kg at the power density of 161.7 W/kg,and the capacitance retention reaches up to 94%after 1000 cycles at a current density of 3.2 A/g.The excellent electrochemical performance of CuO/Ni(OH)2 nanocomposites is attributed to the high mobility of electrons and ions in the CuO component,and the uniform mutual dispersion of Ni(OH)2 and CuO to maintain high specific surface area of Ni(OH)2 nanowhiskers.In addition,the lattice distortion coming from the mutual doping of Cu2+in Ni(OH)2 and Ni2+in CuO provides more active sites for energy storage.The CuO/Ni(OH)2 composite is a highly practical electrode material for supercapacitor that can be industrially prepared by a simple and efficient method of water-boiling treatment.(3)Porous carbon material with high specific surface area was prepared by a one-step pyrolysis of the raw material of fulvic acid.In a nitrogen atmosphere,the fulvic acid was heated at 700? for 3 h.And then,the obtained fluffy porous gray-black powders were washed by 200 ml deionized water for 3 times to remove impurities and dried at 105? for 24 h.Compared with commercial activated carbon(with a specific capacity of 79 F/g at a current density of 1 A/g),the prepared carbon material exhibited significantly superior electrochemical performance(the specific capacity is 128 F/g at 1 A/g with a capacity retention of 93.4%after 10000 cycles).The electrochemical performance of the asymmetric supercapacitor assembled by the CuO/Ni(OH)2 nanocomposite synthesized in the research(2)as the positive electrode and the porous carbon as the negative electrode was significantly improved.The specific capacity is 60 F/g at 1 A/g,the energy density is up to 19.5 Wh/kg at a power density of 781 W/kg,and the capacity retention is 98%after 6000 cycles at a current density of 3.2 A/g.The porous carbon material prepared by the one-step pyrolysis of fulvic acid is a kind of supercapacitor anode material with excellent electrochemical performance and can be industrially prepared,which has great research significance.