In Situ Growth of Novel Graphene Nanostructures in Reduced Graphene Oxide Microspherical Assembly with...

Graphene is extensively investigated for various energy storage systems. However, the very low density (<0.01 g cm^-3 ) of graphene nanosheets has hindered its further applications. To solve this issue, a controlled assembly of 2D graphene building blocks should be developed into graphene microspheres with high packing density, and restacking of graphene should be prevented to ensure an electrochemically accessible surface area during the assembly. Furthermore, graphene microspheres should have multiple 1D external conductive architecture to promote contacts with the neighbors. This study reports in situ growth of novel graphene nanostructures in reduced graphene oxide microspherical assembly (denoted as GT/GnS@rGB) with restacking resistance and interparticle contacts, for electrochemical energy storage. The GT/GnS@rGB showed high gravimetric (231.8 F g^-1 ) and volumetric (181.5 F cm^-3 ) capacitances at 0.2 A g^-1 in organic electrolyte with excellent rate capabilities of 94.3% (@ 0.2 vs 10 Ag^-1 ). Furthermore, GT/GnS@rGB exhibited excellent cycling stability (96.1% of the initial capacitance after 100 000 charge/discharge cycles at 2 A g^-1 ). As demonstrated in the electrochemical evaluation as electrode materials for electrical double-layer capacitors, unique structural and textural features of the GT/GnS@rGB would be beneficial in the use of graphene assembly for energy storage applications.