The contribution of functional groups in carbon nanotube electrodes to the electrochemical performance

In this paper, carboxylic acid functionalized and aminated carbon nanotubes (CNTs) were prepared via mixacid treatment and further amination. In comparison with pristine CNTs, the effect of functional groups on the electrochemical properties was investigated. Transmission electron microscopy (TEM) and Fourier transform infrared spectrophotometer (FTIR) suggested that the highly tangled long ropes of CNT were cut into short, open-ended pipes with the corresponding functional groups grafted successfully onto their surfaces. The amount of functional groups was further determined by acid-base titration. Charge-discharge testing and cyclic voltammetry (CV) were used to characterize the electrochemical behaviors of the samples. It is found that the as-received functional groups, especially the carboxylic groups evidently improved the capacities of the electrodes due to the reversible Faradic reaction. Therefore, functionalized CNTs may be the promising material used in lithium ion batteries to deliver both high reversible capacity and high power capability.