Hierarchical nanohybrids with porous CNT-networks decorated crumpled graphene balls for supercapacitors.

Abstract

One of the most challenging issues in developing supercapacitor technology is the rational design and synthesis of active electrode materials, at the nanoscale, with favorable morphologies, reasonable porous structure, and excellent conductivity. By transforming a two-dimensional (2D) graphene sheet into a crumpled ball shape, a novel three-dimensional (3D) graphene structure with a large surface area and aggregation-resistant properties has been proposed as an active material in supercapacitors to address the issues associated with the restacking of 2D graphene sheets. To further improve the mass transport/electron transfer and address the issue of limited contact spots between the crumpled graphene balls (CGBs) or between the CGBs and the current collector, we report here a unique hierarchical nanohybrid with porous carbon nanotube (CNT)-networks decorated CGBs (p-CNTn/CGBs), which not only greatly improves the affinity for bridging the active material and the current collector but also maintains favorable features for supercapacitor applications, such as a large surface area, 3D hierarchical nanostructure, excellent electrical conductivity, and outstanding aggregation-resistance. The performance established on the p-CNTn/CGBs far exceeded the bare CGB and reduced graphene oxide (RGO) counterparts in terms of specific capacitance and rate capabilities.