High-cell-voltage supercapacitor of carbon nanotube/carbon cloth operating in neutral aqueous solution

Dense and entangled carbon nanotubes (CNTs) directly grown on the carbon cloth (CC) have been employed as hierarchical supercapacitor electrodes in neutral aqueous electrolyte of Na2SO4. XPS and Raman results show the CNTs with large amounts of oxygen functionalities and high degree of disorder, respectively, after treatment of electrochemical oxidation. The voltammograms and galvanostatic charge/discharge are performed to probe the capacitive characteristics of CNTs/CC electrode. Moreover, the symmetric supercapacitor of CNTs/CC exhibits an excellent cyclability over 10 000 cycles and high energy density of 27.8 Wh kg−1, with a wide cell potential of 2 V and a large specific capacitance of 210 F g−1.