Multiwalled carbon nanotubes (MWNTs) were used as the conductive additive in the electrode materials. The electrochemical properties of supercapacitors based on LiNi0.8Co0.2O2 / MWNTs composite and LiNi0.8Co0.2O2/acetylene black composite and MWNTs in 1.0 mol·L-1 LiClO4 / EC+DEC [V(EC)∶V(DEC)=1∶1] electrolyte were investigated by means of constant charge/discharge current tests, respectively. The experimental results show that the LiNi0.8Co0.2O2 / MWNTs composite has better performance than that of others, and the maximum specific capacitance of the supercapacitor can reach 271.6 F·g-1, while the energy density is up to 339.5 Wh·kg-1. Furthermore, it is remarkable that the performance of MWNTs is better than that of acetylene black as the conductive additive.
Nano- sized and well- dispersed Cu- Ni/La2O3 can be obtained by reduction of LaCu0.2Ni0.8O3 with the structure of perovskite. Using Cu- Ni/La2O3 as cata lyst and C2H2 as carbon source, carbon nanotubes with a high yield and narrow di ameter distribution can be obtained in the reaction temperature range of 650～ 7 00℃ . Outer diameter of carbon nanotubes rangs from 9nm to 14nm. TG, Raman and XPS analysis indicate that carbon nanotubes prepared by Cu- Ni/La2O3 are relati vely higher in graphitic degree.
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.
