The Preparation And Electrochemical Properties Of Electrode Composite Materials For Supercapacitors

In recent year,the development of sustainable energy and new storage technologies have been imminent,when the resource have been significantly consumed in global.The supercapacitor as new energy storage devices filled the gap between conventional capacitors and batteries.The high-power density,fast charge and discharge capacity,long cycle life and a series of advantages over supercapacitor have been widely concerned by researchers,which the electrode materials could be major factor to influence the supercapacitor performance.Therefore,the development of high-performance electrode materials is foremost.In this paper,composite materials of PANI/NCNTs,NCNTs@PANI and PANI/CNFs were prepared by in situ polymerization of aniline in solution.The nanocomposites of NCNTs@Co₃O₄ and NiMoO₄@Co₃O₄were prepared by hydrothermal methods.The structure and surface morphology of composite materials were characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD)respectively.The cyclic voltammetry,galvanostatical charge/discharge measurements,and electrochemical impedance spectroscopy were used to characterize the supercapacitor performances of the prepared materials.(1)The PANI/NCNTs was synthesized in different aniline concentration.When the aniline concentration was 0.337 mol/L,the PANI/NCNTs-1 composite was synthesized.At a discharge current density of 0.2 A/g,the specific capacitance of PANI/NCNTs-1 was 1285 F/g.The cycling capacity of 1000 cycles over PANI/NCNTs-1 decreased by 3%with excellent cycling stability.Three type of NCNTs@PANI composites were prepared in dilute solution of aniline.The PANI was loaded on the surface of NCNTs.The excellent supercapacitor performance of NCNTs@PANI was synthesized by adding 40 mg NCNTs,which processed the specific capacitance of 1246 F/g at discharge current density of 0.2 A/g.(2)Composites of PANI and carbon nanofibers(PANI/CNFs)were prepared by chemical oxidation polymerization in different aniline concentrations.The nanocomposites displayed a one-dimensional rod-like structure.The PANI/CNFs-1 composite prepared in aniline concentration of 0.256 mol/L has the best supercapacitor performance.While the discharge current density is 0.2 A/g,the specific capacitance is 877 F/g.(3)The nanocomposites of NCNTs@Co₃O₄ was synthesized by one-step hydrothermal method.A series of NCNTs@Co₃O₄ nanocomposites were prepared by adding different quality of nitrogen-doped carbon nanotubes.The average diameter of the composite was 110nm,which was a one-dimensional nanowire structure.When the discharge current density is0.2 A/g,the specific capacitances of NCNTs@Co₃O₄-1,NCNTs@Co₃O₄-2,NCNTs@Co₃O₄-3,NCNTs@Co₃O₄-4 and NCNTs@Co₃O₄-5 were 1375,1750,2153,2388 and 2403 F/g respectively.The specific capacitances of NCNTs@Co₃O₄-4 and NCNTs@Co₃O₄-5 decreased by 19%after charg/discharg processes of 5000 cycles.(4)The NiMoO₄ nanowires were prepared by hydrothermal method.The SEM results showed that the diameter was 60?120 nm.While the reaction time was 4h,the synthesized NiMoO₄nanowires have excellent supercapacitor performance.When the discharge current density was 0.2 A/g,the specific capacitance was 640 F/g.After 5000 cycles,the initial specific capacitance was maintained at 74.3%(444 F/g).The NiMoO₄@Co₃O₄ composite was further prepared by a hydrothermal reaction method.The diameter of the composite was about 100 nm.When the discharge current density was 0.2 A/g,the specific capacitance of the NiMoO₄@Co₃O₄composite which prepared by hydrothermal reaction for 4 hours was 1215F/g.The specific capacitance only decreased by 11%after 3000 cycles of charge/discharge at a current density of 1 A/g.The results showed that the prepared processes of nanocomposites have excellent supercapacitor properties and potential in the field of energy materials.