Unconventional Synthesis of Large Pore Ordered Mesoporous Carbon Nanospheres for Ionic Liquid-Based Supercapacitors

Ordered carbon spheres with enlarged mesopores have been considered to be desirable carbon electrodes for ionic liquid-based supercapacitors. New synthesis of these materials to use commercially available soft templates is yet to be developed. In this study, we demonstrate that by silica encapsulation of self-assembled polymer nanospheres prepared using commercially available Pluronic F127, mesopore sizes of obtained carbon nanospheres can be enlarged from micropores to large mesopores up to 10.7 nm in size. A linear relationship between the mesopore size and the thicknesses of silica nanocages has been established, which enables us to alter the mesopore sizes in a controlled manner. The two-electrode test in EMI-BF4 electrolyte demonstrates that mesoporous carbon nanospheres show a capacitance of up to 113 F g(-1) at 10 A g(-1). They also exhibit an excellent energy density (E) of 56 W h kg(-1) (working voltage of 4.0 V). Such high capacitance, outstanding rate capability, and excellent power density (P) are owing to enlarged mesoporous channels and large specific surface area allowing rapid mass transportation and full use of the surface area.