Investigation On Electrochemical Performance Of Biomass Carbon Materials And Copper Electrode

Supercapacitors are studied by the majority of researchers because of the advantages of high specific capacity,high power density,fast charge and discharge characteristics and long cycle life.The biomass carbon material sources are extensive,environmental-friendly and renewable;They can be activated to control the pore size,which can effectively improve the specific capacity and other electrochemical performances of supercapacitors.Biomass carbon materials are current researching hot directions.In this paper,cotton and pomelo peel were selected as the carbon sources,with the activating agent KOH to prepare porous biomass carbon materials.Assembled supercapacitor to study their capacitance properties.Considering that the amount of activating agent and sintering temperature were the two main factors which had great influence on the structure of carbon materials,this paper studied the effects of different ratio of KOH and sintering temperatures on the electrochemical properties of the activated carbon materials.The results showed that the activated carbon materials prepared using cotton as the carbon source,when the ratio of alkali and carbon was 2:1,emerged the best electrochemical performances under the sintering temperature of 900℃.The specific capacity could reach 318 F/g with the current density of 1 A/g.As for pomelo peel as the carbon source,when the ratio of alkali and carbon was 2:1 and the sintering temperature was 800℃,the activated carbon materials showed the best electrochemical performances.The specific capacity could reach 290 F/g with the current density of 1 A/g.XRD,SEM,Fourier Transform Infrared Spectroscopy and BET were characterized.The prepared activated carbon materials were amorphous carbon with a certain degree of graphitization and showed porous structure with different sizes which were good for improving the conductivity of carbon materials and their electrochemical properties.The charge transfer resistance of the nano-sized copper thin film electrode was also studied in this paper.Cu films with different thicknesses from 15 nm to 100 nm were prepared by magnetron sputtering on silicon wafers.Cu films were analyzed by the X-ray diffraction(XRD),Scanned electron microscopy(SEM),Transmission electron microscopy(TEM),Energy dispersive spectrometer(EDS)and Glow discharge spectra(GDS),The electrochemical impedance spectra of Cu films were investigated in 1M Na2SO4 to elucidate the size effect of the charge transfer resistance in nano-sized dimensions,and the result shows the charge transfer resistance of Cu films is strongly influenced by the thickness of the films.The increase in the thickness of thin metal films leads to the decrease of the charge transfer resistance and double layer capacitance.The relationship between the charge transfer resistance and the thickness of the thin metal film electrodes follows the same rule as that of the resistance of thin film metal and its thickness.The current work provided further understanding on the electrochemical behavior of electrode materials in nano-sized dimensions and the design guidance for improving the performance of energy storage device.