Uniform diffusion of acetonitrile inside carbon nanotubes favors supercapacitor performance

An unusual behavior of liquid acetonitrile (AN) confined inside carbon nanotubes (CNTs) is predicted by molecular dynamics simulation. In contrast to water, which shows inhomogeneous variation of both translational and rotational diffusion with CNT diameter [ Nano Lett. 2003, 3, 589; 2004, 4, 619], the diffusion coefficient of AN changes uniformly and can be described by a simple analytic model. At the same time, the reorientation dynamics of AN vary irregularly in smaller CNTs because of specific packing structures. The uniform translational diffusion of the nonaqueous solvent is critical for stable performance of the new generation of supercapacitors [ Nat. Mater. 2006, 5, 987].