Effect of Single-Walled Carbon Nanotubes as Conductive Additives on the Performance of LiCoO2-Based Electrodes

Abstract

Single-walled carbon nanotubes (SWNTs) and carbon black (CB) were used as conductive additives in lithium-ion batteries. Composites containing nanostructured and carbon additives were applied as positive electrodes in coin-type electrochemical cells with Li metal as a counter electrode. The conductive SWNTs with their wirelike shape and high aspect ratio are proved to have significant impact on the electrochemical performance of the electrode. The electrode composite containing of SWNTs has an internal resistance comparable to that of the of carbon black. Whereas the discharge capacity of the electrode containing of CB drops to 0 when increasing the rate to 5C, the capacity of the electrode containing the same weight fraction of SWNTs retains 67% of its initial capacity even at 18C. Cycling performance measured up to demonstrates that the SWNTs at a low concentration are as efficient in the capacity retention as the of carbon black. We interpret the SWNT-induced electrode performance by formation of a flexible, electrically wired network of conducting SWNTs in close contact with nano-particles, which accelerates the exchange of the Li ions and allows a rapid transfer of electrons throughout the electrode.