Long-Cycle Electrochemical Behavior of Multiwall Carbon Nanotubes Synthesized on Stainless Steel in Li Ion Batteries

Carbon nanotubes (CNTs) are considered to be excellent candidates for high performance electrode materials in Li ion batteries. The nanometer-sized pore structures of CNTs can provide the hosting sites for storing large numbers of Li ions. A short diffusion distance for the Li ions may bring about a high discharge rate. The long-cycle performance of aligned multiwalled carbon nanotubes (MWNTs) directly synthesized on stainless-steel foil as an anode material in lithium battery is demonstrated. An increase in the specific capacity with an increase in the cycle number is observed. Starting at a value of 132 mA hg(-1) in the first cycle at a current rate of 1 C, the specific capacity increased about 250% to a value of 460 mA hg(-1) after 1200 cycles. This is an unusual but a welcoming behavior for battery applications. It is found that the morphology of the MWNTs with structural and surface defect and the stainless-steel substrate play an important role in enhancing the capacity during the cycling process.