A novel electrode material, modified activated carbon aerogel, produced by grafting a vinyltrimethoxysilane (vtmos) functional group on the surface of activated carbon aerogel (ACA), has been developed for high-energy storage in electric double layer capacitor (EDLC). Surface modification with surfactant vtmos enhances the hydrophobicity of ACA and its affinity to propylene carbonate (PC) solvent, which improves the wettability of ACA in a PC-based electrolyte solution, resulting in not only a lower resistance to the transport of electrolyte ions within ACA micropores but also more accessible surface area for the formation of an electric double layer, and accordingly, higher specific capacitance and energy density.