Modification of the structure of multi-walled carbon nanotubes by choice of catalyst and their electro-chemical behavior

The multi-walled carbon nanotubes (MWCNTs) grown over a newly introduced catalyst of LiNi0.5Co0.5O2 by decomposition of acetylene gas have been evaluated for their electro-chemical properties in the context of structural modification as revealed by X-ray diffraction (XRD) and first order Raman spectrum. The observed interlayer spacing (d0 0 2) of 3.42 Å is 2.1% larger than that of graphite and is marginally higher (3.40 Å) than that of MWCNTs grown over other conventional catalysts. The tube diameters lie in the range of 5-40 nm. There is up-shift in G-band and a larger full width half maximum of the peak in the first order Raman spectra as compared to those of graphite and MWCNTs catalyzed by other conventional catalysts. The first discharge capacity is 765 mAh g−1 as compared to the MWCNTs grown over other conventional catalysts, exhibiting capacities between 80 and 640 mAh g−1. The reversible capacity of the MWCNTs grown in the present study is 485 mAh g−1, which is higher than 100-400 mAh g−1 capacity observed in MWCNTs grown over other conventional catalysts. The columbic efficiency in the first cycle is observed to be nearly 65% and from second to eleventh cycle, it is nearly constant at 96.6%.