Cycle and rate performance of chemically modified super-aligned carbon nanotube electrodes for lithium ion batteries

Super-aligned multi-walled carbon nanotubes (MWCNTs), which had been produced in large-scale, were oxidized by H2O2 and HNO3. The surface defects and oxygen-containing functional groups introduced during the oxidizing process were characterized by Raman spectroscopy and X-ray photoelectron spectroscopy. The surface modification of MWCNTs improved the electrochemical properties. As a result, H2O2-treated and HNO3-treated MWCNTs displayed reversible capacities of 364 mA h/g and 391 mA h/g, respectively, after 80 galvanostatic cycles, corresponding to 143% and 154% improvements compared with pristine MWCNTs. The rate capability was also increased. At a current density of 3500 mA/g, H2O2-treated and HNO3-treated MWCNTs exhibited reversible capacities of 66 mA h/g and 156 mA h/g, respectively. In contrast, pristine MWCNTs were only able to deliver 27 mA h/g at this current density.