Enhanced capacitance in partially exfoliated multi-walled carbon nanotubes

We report for the first time the enhanced capacitance of multi-walled carbon nanotubes (MWCNTs) after exfoliation. Transmission electron microscopy studies confirmed that the MWCNTs were partially exfoliated with improved effective surface area. Carbon cloth electrode deposited with partially exfoliated carbon nanotubes (Ex-CNTs) yielded specific capacitances in a range of 130–165 F g−1 at charging/discharging current densities from 5 to 0.5 A g−1, with coulombic efficiencies of ∼98%. The specific capacitance of Ex-CNTs was an order of magnitude higher than untreated MWCNTs, and comparable to graphene at all charging/discharging current densities we studied. The enhanced capacitance can be attributed to improved effective surface area and increased defect density of the exfoliated tubular structure. The results declared that Ex-CNTs are promising electrode materials for high-capacitance supercapacitors.

Research highlights
► First demonstration of enhanced capacitance of exfoliated carbon nanotubes (Ex-CNTs).
► Increased surface area and defect density improve specific capacitance of Ex-CNTs.
► Specific capacitance of Ex-CNTs is at least 10 times higher than untreated CNTs.
► Specific capacitance of Ex-CNTs is comparable to graphene.