Sensitive G-Band Raman Features for the Electrical Conductivity of Multi-Walled Carbon Nanotubes

We have studied the structural parameters of catalytically grown highly disordered multi-walled carbon nanotubes that were heat treated at temperatures between 1200 degrees C and 2600 degrees C in an argon atmosphere. Rather than the interlayer spacing or the R value (the intensity of the D band divided by the intensity of the G band), we found that the half width at half maximum intensity of the G band was the most sensitive parameter that is correlated with the altered electrical conductivity of an individual carbon nanotube that had been heat treated at high temperatures. This is because one-dimensional nanocarbons exhibit a preference for two-dimensional structural development along the length of the tube due to the limited mobility of carbon atoms along the circumferential direction. Tubes heat treated at 2200 degrees C exhibited both a high electrical conductivity and an absence of lithium-ion intercalation, and thus are the best conductive filler for the active materials of lithium-ion batteries for long-term stability.