Nanowindow-Regulated Specific Capacitance of Supercapacitor Electrodes of Single-Wall Carbon Nanohorns

The solvated ion size of electrolytes increases in the following order; SO<sub>4</sub><sup>2-</sup>(H<sub>2</sub>O)<sub>12</sub> (0.53 nm) < (C<sub>2</sub>H<sub>5</sub>)<sub>4</sub>N<sup>+</sup>·7acetonitrile (Et<sub>4</sub>N<sup>+</sup>·7ACN, 1.30 nm) < (C<sub>2</sub>H<sub>5</sub>)<sub>4</sub>N<sup>+</sup>·4propylene carbonate (Et<sub>4</sub>N<sup>+</sup>·4PC, 1.35 nm). The size difference between the nanowindows of single-wall carbon nanohorns and the solvated ions of electrolytes should be an important factor in the accessibility of the ions to the internal spaces through the nanowindow.