Preparation And Energy Storage Performance Of Carbide-derived Carbon And Their Composites

Silicon carbide and silicon carbide/mesophase pitch carbon precursors were synthesized by pyrolysis of polycarbosilane?PCS?and its mixture with mesophse pitch at higher temperature.Subsequently,silicon carbide-derived carbons?SiC-CDCs?and silicon carbide derived carbon/mesophase pitch carbon composites?SiC-CDCs/MPC?were obtained via chlorination of the corresponding precursors at 1000oC.The microstructure,morphology and pore structure and distribution of the SiC-CDCs and SiC-CDCs/MPC were characterized by X-ray diffraction pattern?XRD?,Raman spectroscopy,transmission electron microscope?TEM?and N₂ adsorption/desorption method.The effects of pyrolysis temperature on the crystal phase,morphology,pore size and distribution of the SiC-CDCs and SiC-CDCs/MPC were investigated and the electrochemical performances as the electrode of supercapacitors were evaluated.The results show that:?1?SiC-CDCs with higher specific surface areas and sub-nanometer pores can be successfully prepared by chlorination of SiC precursors.Meanwhile,SiC-CDCs exhibit better specific capacitances and supercapacitive performances at different current densities.?2?By pyrolysis the mixture of PCS and MP with different mass ratios at 1800?C,the SiC/MPC precusors were synthesized.Subsequently,SiC-CDCs/MPC can be prepared by chlorination of SiC/MPC-1800 precursors.The composites as the electrode materials of supercapacitors show better electrochemical performances under the different current densities.And the composite with mass ratio of PCS/MP 1.5:1 exhibits the highest capacitance and the optimal electrochemical performance.?3?By pyrolysis the mixture of PCS and MP with the mass raitio of 1.5:1 at different temperatures?1200oC,1600oC,1800oC,2400oC,respectively?and subsequently chlorination,SiC-CDCs/MPC composites were prepared.The composites show higher specific capacitance as super capacitor electrode materials.Especially,the composites pyrolysized at 1600°C show the highest capacity,and can still show better supercapacitive performance and rate performance under the different current densities.