Structural characterization and electrochemical lithium insertion properties of carbon nanotubes prepared by the catalytic decomposition of methane

Abstract

Carbon nanotubes (CNTs) were synthesized by the catalytic decomposition of methane at 773, 873 and 973 K. Structures of these carbon nanotubes were characterized by TEM, HRTEM, XRD and Raman spectra, respectively. The results showed that with the increase of preparation temperature, the d(002) value of the CNTs decreased, while the L-a values and the degree of crystallihity of the samples increased. Electrochemical lithium insertion properties of the CNTs used as positive electrodes in CNTs/Li cells were also investigated. The first charge capacities of CNTs/Li cells were 290, 254 and 202 mAh/g for samples produced at 773, 873 and 973 K, respectively. The sample from 773 K showed a larger charge capacity, which is attributed to the accommodation of lithium at microcavities, at edges of graphitic layers and at the surface of single graphitic layers. Its potential hysteresis during U insertion and deinsertion processes may be related to the interstitial carbon atoms

Carbon nanotubes for clean energy applications

“…It was assumed that the central cores of MWNTs played a role in the accumulation of Li ions as well as in the creation of an electrical double layer, and hence their closing with thermal treatment and the formation of continuous carbon layers were unfavourable for lithium absorption. Similarly, Wu et al [124] studied the structure and lithium insertion behaviour of MWNTs grown at different temperatures by the catalytic decomposition of methane. It was found that the lithium storage capacity of the MWNTs decreased with an increase in the growth temperature.…”