The Synthesis And Performance Of High Capacitance Biomorphic Carbon Material

The microstructure and composition of carbon materials are important factors influencing their capacitive properties.In this dissertation,the carbons were prepared by using soybeans and a mold as the precursors.The microstructure and morphology of the cathode materials were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS).Electrochemical properties were tested by cyclic voltammetry(CV),galvanostatic charge/discharge and electrochemical impedance spectroscopy(EIS).A porous biomorphic carbon with 17.23% of nitrogen and 23.23% of oxygen is synthesized by using KOH-soaked soybeans as the precursor.The as-obtained porous carbon material exhibits a specific surface area of 343.5m2g-1and a total pore volume of0.613cm3 g-1.The electrochemical tests show that the carbon electrode material exhibits high specific capacitance of 391 F g-1 at a current density of 0.5A g-1 and excellent cycling stability of 100% after 10,000 cycles at a current density of 10 A g-1.The result of EIS tests shows that the charge transfer resistance is only 0.852?.A novel biomorphic heteroatom-doped porous carbon with 2.86% of nitrogen and12.36% of oxygen is synthesized by using a mold as the precursor.The SEM images suggest that the carbon material has a three dimensional bulk architecture with high stacking density and porous structure.The result of BET test reveals that the carbon material has mesoporous and microporous structure,exhibits a specific surface area of86m2 g-1 and a total pore volume of 0.064cm3 g-1,the particle density is calculated to be1.77 g cm-3.The electrochemical tests indicate that the biomorphic porous carbon electrode material exhibits an ultra-high volumetric capacitance of up to 655 F cm-3at current density of 0.5A g-1 and superior cycle stability of 100% after 10,000 cycles at a current density of 10 A g-1.The result of EIS test shows that the charge transfer resistance is 0.608?.