Preparation Of 3D Hierarchical Structure Nickel-cobalt (hydrogen) Oxide Composite Material And Research On Capacitor Performance

Supercapacitors have the advantages of high power density,high cycle life,fast charge and discharge rate,environmentally friendly,which meet the characteristics of storage and utilization of green renewable energy.Therefore,the research on supercapacitors is a hot topic in the field of energy.Electrode material is the most important factor affected the performance of supercapacitors,and the performance of electrodes depends on their chemical composition and micro structure.Therefore,it is very important to design reasonable microstructures and chemical components of electrode material to improve the performance of supercapacitors.In this paper,carbon fiber cloth was used as flexible conductive substrate,nickel-cobalt(hydrogen)oxide was used as active material,and 3D multilevel structure carbon cloth/nickel-cobalt bimetal composite material were prepared by designing a reasonable synthetic route.The multi-level structure and the synergistic effect between the compounds improved the disadvantage of low specific capacity of the single component.The main contents of this article were as follows:(1)Firstly,the cobalt carbonate nanosheets with characteristic structure were grown on carbon fiber cloth by hydrothermal method(CC@CCH NS);then the layered nickel-cobalt double hydroxide(NiCo LDH)was grown on cobalt carbonate nanosheets by electrodeposition(CC@CCH NS@NiCo LDH).After annealing,the electrode material of CC@Co3O4@NiCo2O4 with well-structured structure was obtained.The micro structure and electrochemical properties of the prepared samples were studied by various characterization techniques.The electrochemical data analysis showed that CC@Co3O4@NiCo2O4 had specific capacitance of 1175 mF/cm2 at 2 mA/cm2 and had an ideal rate performance.EIS test showed that the introduction of carbon fiber cloth and bimetal system improved the properties of composites.(2)A novel array structure was designed.One-dimensional cobalt carbonate hydroxide nanorod arraywas were grown on carbon fiber cloth(CC@CCH)in situ.ZIF-67 was grown using cobalt carbonate hydroxide nanorod array as sacrificial template,finally,it was transformed into hollow nickel-cobalt dihydroxide nanocage(LDHC)arrays,and the carbon cloth@cobalt carbonate hydroxide nanorod arrays@nickel-cobalt dihydroxide nanocage hybrid arrays(CC@CCH-LDHC HAs)with 3D hierarchically structure were obtained.The microstructure and electrochemical properties of the samples were confirmed by various characterizations,the results showed that the CC@CCH-LDHC HAs electrode had a high specific capacitance of 1700 F/g at 2 A/g.The sample still shows 78.2%rate performance when the current density increased to 50 A/g.The CC@CCH-LDHC HAs still had 91.1%initial capacitance at 10 A/g after 2500 cycles.