The Preparation And Electrochmical Properties Of MCMB/CNTs Hybrids

Mesocarbon microbeads(MCMB)possess excellent electrical conductivity,and stable physical and chemical properties.It can be used in the electrode material of lithium-ion batteries.Moreover,carbon nanotubes(CNTs)can be used as electrode materials for batteries and super capacitors due to its high specific surface area and excellent electrical conductivity.However,the lower specific surface area of MCMB limits the application in the field of super capacitor.In this paper,the nanostructure hybrids have been grown on the surface of the graphitizing MCMB via a simple chemical vapor deposition(CVD)method,the prepared hybrids will be applied for the electrode materials of supercapacitors.In this study,we prepared CNTs by CVD method,and iron nitrate nonahydrate was used as catalysts,acetylene was used as carbon source,hydrogen was used as reaction gas,and argon was used as carrier gas.Changing the growth temperature and the flow ratio of H2 to C2H2(r)to control the morphologies of the hybrids.In addition,the various morphologies have a significant effect on the electrochemical properties.The results show that obtained CNTs are uniform with an average diameter of 23 nm and have a high productivity when r = 2 at 750?.Increasing the growth temperature and the ratio of H2 to C2H2 is not conducive to the growth of CNTs.The prepared products include sheets,fibers,and tubes.Among of them,MCMB-NS-2-750 has a higher specific surface area.Its specific capacitance is up to 320 F/g at the current density of 0.5 A/g,which is approximately 1.54 folds of graphitizing MCMB.Moreover,it has a superior cycling stability,the specific capacitance retention can reach to 93%after 500 cycles.