Preparation Of Polyaniline Based Composites And Their Application In Supercapacitors

Nowadays,with the traditional energy increasingly dried up and the environment polluted gradually serious,it is urgent to save energy and protect the environment.As a new clean and highly efficient energy resource,supercapacitors,have attracted much attention due to the need of the development of the modem society.However,its low energy density is the biggest problem that limits the widespread application of supercapacitors According to the energy density equation,E=1/2CV2,The magnitude of the capacitance and the operating voltage will directly affect the magnitude of the energy density.Therefore,trying to improve the specific capacitance and expand the working potential window of supercapacitors is the most effective measure to increase its energy density.This paper improves the specific capacitance and working voltage of supercapacitors by synthesizing polyaniline-based composites and designing asymmetric-capacitors.Thence,it can achieve the purpose of optimizing the performance of the supercapacitors.Synthesis of polyaniline nanowires/reduced graphene oxide composites by in situ chemical oxidation polymerization assisted by hydrothermal method.Polyaniline nanowires/graphene oxide(PANI/GO)composites was formed by the addition of the aniline monomers into the aqueous solution of different concentrations of graphene oxide with ammonium persulfate(APS)as oxidant at room temperature,and followed by hydrothermal reduction to obtain polyaniline nanowires/reduced graphene oxide(PANI/rGO)composites.Characterizing the micro-morphology and structure of prepared products by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray powder diffraction(XRD),Fourier transform infrared(FTIR)spectroscopy and Raman spectroscopy.And the electrochemical tests were carried out in the sulfuric acid solution by three electrode and two electrode systems respectively.As a result,Polyaniline nanowires with a diameter of 30~50 nm attached on the graphene layers.The specific capacitance of as-prepared composites electrode is 580 F g-1 at a current density of 1 A g-1,superior to the pure polyaniline(380 F g-1).The composites as electrodes to design a symmetrical supercapacitor.Electrochemical characterizations show the excellent power density(5 kW kg-1)and energy density(9.03 Wh kg-1)of the symmetric supercapacitor.There is no obvious attenuation after 2000 cyclic of charge and discharge,indicating its excellent cycle stability and long cycle life.The polyaniline nanowires/reduced oxide graphene(PANI/rGO)on carbon cloth was synthesed by one-step cyclic voltammetry electrodeposition.The micromorphology and structure of the obtained samples were characterizated by FESEM,TEM,XRD,FT-IR and Raman.Electrochemical tests were carried out to evaluate the performance of the composites electrode.The results show that PANI was grown on rGO fragment with cross-linked nanowire network.The introduction of rGO fragment provided more loading sites for the growth of polyaniline nanowires,while the rGO fragment also make a greater contribution to improve specific surface area of the composites.The specific capacitance of PANI/rGO composites is 581 F g-1,which is higher than pure PANI(405 F g-1).The specific capacitance of the composites is increased by about 40%,compared with the pure PANI.it also shows a remarkable cycling stability with the retention of 86 % at a current density of 1 A g-1 after 2000 cycles of charge and discharge.A novel asymmetric supercapacitor is assembled using PANI/rGO and 3D rGO gel as positive and negative electrodes,respectively.The electrochemical performance of the asymmetric-capacitor was tested in 1 mol L-1 H2SO4 solution.Electrochemical characterizations indicate that the asymmetric-capacitors exhibits good rate capability and cyclic stability.The PANI/rGO//rGO gel asymmetriccapacitors has great potential applications on energy storage device.