Preparation Of Carbon Tube Electrode Materials And Their Applications Of Supercapacitors

Supercapacitor has the features of high power density,high cycle stability and high charge and discharge efficiency.It is widely used in new energy vehicles,communications equipment,military and other fields.Electrode material is the key factor to determine the performance of supercapacitors.Among numerous electrode materials,the hollow carbon tube has advantages of high specific surface area utilization and good conductivity,but it also has the problems of high cost and easy stacking,etc.In order to solve these problems,two kind of new carbon tube electrode materials were prepared and applied in supercapacitors.(1)The N,P co-doped carbon microtubes were prepared by biomass cotton.According to the structural characterizations,it was found that P and N,P doping could increase the number of micropores,enlarge the specific surface area,improve the hydrophilicity of materials and introduce pseudo-capacitance.The electrochemical tests show that the specific capacitance is 332 F/g at current density of lA/g and 65 times higher than that of pure carbon microtube materials when the concentration of phytic acid is 2 wt%and the carbonization temperature is 800 ?.When the concentration of phytic acid is 2 wt%and the concentration of urea is 10 wt%,the specific capacitance of N,P co-doped carbon microtubes is 384.8 F/g.This is due to the synergistic effect of specific surface area,pore size structure and functional groups containing phosphorus and nitrogen.(2)Porous carbon nanotube/graphene oxide composites were prepared by air oxidation and hydrothermal method.According to the structural characterizations,it is found that air oxidation can greatly increase the structural defects of carbon nanotubes.The multi-channel pore structure can be formed with the composite of graphene oxide which can increase the specific surface area and the capacitance of the electric double layer.When mass ratio of carbon nanotubes and graphene oxide is at 1:1,the specific capacitance of composites is 221.2 F/g at the current density of 1 A/g.The experimental results show that the new carbon tube electrode materials prepared in this paper solve the problems existing in the application of carbon tubes in supercapacitors to a certain extent.