Exfoliation from carbon nanotubes versus tube size on lithium insertion

Exfoliation from multiwalled carbon nanotubes (MWCNTs) during electrochemical insertion of lithium is shown to depend on the inner diameter of the tubes and the wall thickness. Those with core diameters of 10 nm and walls 5 nm thick showed no incorporation of solvated Li+ ions into the core and exfoliation as a result of solvated Li+ ions entering the walls; those with core diameters of 40 nm with walls 30 nm thick showed no exfoliation in an electrolyte based on ethylene carbonate (EC) and little exfoliation even in electrolytes based on propylene carbonate (PC). Exfoliation of graphene layers from a MWCNT on lithium insertion depends not only on the size of the solvated Li+ ions, but also on the concentration of the solvated Li+ ions between the graphene layers in the walls. (C) 2010 Elsevier B.V. All rights reserved.