Three-Dimensional Graphene Network As a Highly Macro-Porous, Flexible and Large-Scale Electrode for Supercapacitor Application

Abstract

Graphene, a two-dimensional (2D) carbon nanomaterial, was widely used in many electrochemical applications due to their high mechanical strength, good chemical stability, high specific surface area, and excellent electrical conductivity. However, the major concern for those applications was the activity reaction surface area of the 2D plane structure of graphene. Therefore, in order to enhance the reaction surface area of graphene, the development of a highly porous network-macrostructure with large surface area three-dimensional graphene is an effective strategy to be achieved for electrochemical applications. In this study, we reported an effective and simple method to prepare highly macro-porous, large-scale and flexible three-dimensional graphene foam (3D GF) which was synthesized on the commercial nickel network via the chemical vapor deposition (CVD) method. The quality of 3D GF was investigated by using a Raman spectroscopy. A field-emission scanning electron microscopy was used to examine the surface morphology of 3D GF. A high-resolution transmission electron microscopy was utilized to analyze the inter-layer distance and the number of layers of graphene. Raman results revealed the highly uniform performance of the large-scale 3D GFs. The cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS) were carried out to examine the electrochemical properties. Compared with the traditional 2D plane-structure graphene synthesized on the Ni foil, the CV and EIS results measured by the 3D GF confirmed its superior capacitive behavior, higher specific surface area, and also demonstrated the excellent power capabilities with a low solution resistance and charge transfer resistance. It was found that the specific capacitance of 3D GF was three times larger than the traditional 2D plane-structure graphene. In this study, a tube furnace thermal CVD was utilized to synthesize the large-scale 3D GF. The Ni forms can be curled and loaded into the tube furnace for CVD processes to fabricate the large-scale 3D GFs easily. We provided an easy method to fabricate the highly macro-porous, large-scale and flexible 3D GFs for the future graphene-based potential applications.