Study On The Preparation And Capacitance Of Selenium-based Composites

Supercapacitors(SCs)have attracted great interest due to their important application in electrochemical energy storage,electric vehicles and electric devices at high pulse power level.As well known,the electrode material is an important issue in supercapacitors.In view of unique photoelectric property and electrochemical activity of selenium element,in this paper,a series of selenium-containing materials were prepared.The products as-prepared were characterized by scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffractometer(XRD),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectrometer(FTIR),Raman spectrometer(Raman),Thermogravimetry analysis meter(TG)and so on.The electrochemical and capacitive properties of the products were studied on Electrochemical workstations.The main contents as follows:1.Self-catalytic synthesis and capacitance properties of selenium/polyaniline compositeThe selenium/polyaniline composite was synthesized in situ by redox reaction between H2SeO3 and aniline,where H2SeO3 was formed by dissolving selenium dioxide in water.In the process of the reaction,the elemental selenium formed at first has the catalysis to the redox reaction between H2SeO3 and aniline.Then the reaction was accelerated and the selenium/polyaniline composite was formed.The morphology,crystal form,structure,chemical composition were characterized by SEM,TEM,XRD,Raman and XPS,respectively.It was found that the hexagonal elemental selenium/polyaniline spherical composite was formed in the presence of surfactant CTAB.The test results for capacitance performance show that compared with singe selenium or polyaniline,selenium/polyaniline composite has larger specific capacitance(451.16 F-g-1,at 1 A·g-1),with a good charge-discharge cycle stability.2.Simple synthesis of nickel diselenide and its capacitive propertiesTaking elemental selenium and nickel chloride as precursors,the nickel diselenide was prepared by a water bath-calcination process.For the nickel diselenide product,the crystal form was determined by XRD,the morphology was characterized by SEM,and the chemical composition was determined by XPS and Raman spectrum.Finally,the specific capacitance of the product was measured on electrochemical workstation.The test results show that the morphology of the product was transformed from large spheres to pure nickel diselenide nano-particles after calcinations.The capacitance tests show that the calcined product has high specific capacitance of the(1708.8 F·g-1,1 A·g-1),since the calcined product has large specific surface area and high purity.3.Simple synthesis and capacitance properties of cobalt-nickel seleniteA new selenite Co0.8Ni0.7(OH)SeO3 was synthesized by the precipitation reaction,in which sodium selenite was added into cobalt nitrate and nickel nitrate mixture solution.The SEM,XRD,XPS,ICP,FTIR,Raman and TG were respectively used to character the morphology,crystal form,chemical composition and thermal stability of the products as-synthesized.The capacitance test results show that Co0.8Ni0.7(OH)SeO3 had high specific capacitance(1776 F·g-1,,1 A ·g-1)and good cycle stability due to the synergistic effect of the electrochemical active components in selenite,such as Co2+,Ni+ and Se4+.