Controllable Preparation of 3D Graphene with Different Morphologies for High-Performance Electrode Materials.

Abstract

Synthesis of three-dimensional (3D) graphene with controlled morphologies has been achieved by changing the freeze-drying process of graphene in this paper. The obtained vertically aligned graphene (VAGN) is stand-up and has a uniform, dense, and porous network, while the obtained graphene foam (GF) just has a cross-linked 3D porous framework. In addition, the possible growth mechanisms of these nanostructures have been studied based on the experimental results. Furthermore, the effects of morphologies on their electrochemical performances have been investigated. The result shows that the VAGN-based supercapacitor has a higher specific capacitance (Csc) of 182 F g–1 at 0.5 A g–1 than that of GF (160 F g–1 at 0.5 A g–1). The supercapacitors prepared by VAGN and GF retain about 95.7 and 92.7% of Csc, respectively, after 2000 charge–discharge processes. When the power density of the supercapacitor prepared by VAGN is about 50.3 W kg–1, its maximum energy density can reach 7.05 Wh kg–1, which is higher than that of GF. This shows that VAGN has better electrochemical performance than GF. It might be because the aligned structure of VAGN plays an important role in reducing the internal resistance of the electrodes and accelerating ion and electron transport. Three-dimensional graphene with different morphologies might have potential applications as electrode materials for supercapacitors.