Cutting-processed single-wall carbon nanotubes with additional edge sites for supercapacitor electrodes

Carbon nanotubes are frequently selected for supercapacitors because of their major intrinsic properties of mechanical and chemical stability, in addition to their excellent electrical conductivity. However, electrodes using carbon nanotubes suffer from severe performance degradation by the phenomenon of re-stacking during fabrication, which hinders ion accessibility. In this study, short single-wall carbon nanotubes were further shortened by sonication-induced cutting to increase the proportion of edge sites. This longitudinally short structure preferentially exposes the active edge sites, leading to high capacitance during operation. Supercapacitors assembled using the shorter-cut nanotubes exhibit a 7-fold higher capacitance than those with pristine single-wall nanotubes while preserving other intrinsic properties of carbon nanotubes, including excellent cycle performance and rate capability. The unique structure suggests a design approach for achieving a high specific capacitance with those low-dimensional carbon materials that suffer from re-stacking during device fabrication.