Electrochemical deposition of nanostructured manganese oxide on hierarchically porous graphene carbon nanotube structure for ultrahigh-performance electrochemical capacitors

A 3D graphene sheetecarbon nanotube (GS-CNT) structure with a good wetting property, high porosity, and large surface area is homogeneously deposited with active amorphous manganese oxide (a-MnO_x) by potentiodynamic deposition. The flowery a-MnO_x nanostructure with ultra-slender petals (ca. 5-8 nm) on the framework of hierarchically porous GS-CNT matrix not only enables nearly full utilization of a-MnO_x but also retains sufficient conductivity and porosity for the high-rate chargeedischarge application. The use of a-MnO_x on the 3D GS-CNT material produces a specific capacitance of MnO_x of 1200 F g
^-1 which is much-higher than that of a pure a-MnO_x electrode (C_S,Mn = 233 F g
^-1). The specific energy and specific power of a-MnO_x/GS-CNT are respectively as high as 46.2 Wh kg
^-1 and 33.2 kW kg
^-1, revealing that our work conceptually provides away to produce porous structures composed of graphene, carbon nanotubes, and various electroactive materials for high-performance energy storage devices.

This paper was originally published in Journal of Power Sources (2013) 225, 347-355.