Five kinds of multi - walled carbon nanotubes were prepared by CVD(Chemical Vapour Deposition)and puri - fied under the same conditions,then were used as electrodes for super capacitors in order to compare their per - formance.The differences measured in terms of specific capacitance by galvanostatic cycling were presented,porosity measurements using nitrogen at77K made on carbon nanotubes allowd a better understanding of the electrochemical behavior of these carbon nanotubes.The experiment results show that pore diameter in the range of more than3nm is required to maximize the capacitance in the electrolyte of1.0mol · L -1 LiClO 4 /EC+DEC(V EC ∶ V DEC =1 ∶ 1),and the BET surface area contributed by this extent is almost linear with the specific capacitance,in which an average value is about0.11F · m -2 ,and the specific capacitance estimated from above is very close to the value by experiment.
