Vertically aligned graphene prepared by the electrochemical anodization of graphite foil for supercapacitor electrodes

Abstract

Vertically aligned graphene (VAG) improves the specific capacitance of electric double layer capacitor (EDLC) electrodes, because VAGs increase the specific surface area of electrode and promote ion diffusion. Herein, we demonstrate a facile approach for preparing the VAGs with outstanding areal specific capacitance by electrochemical anodization of graphite foil (GF). As the anodizing time increases, the graphite layers in the anodized GF (AGF) electrodes expand due to ion intercalation and bubbles. Each graphite layer is vertically aligned, resulting in the formation of VAG sheets on the GF surface. The AGF electrode exhibits an excellent specific areal capacitance of 2.79 Fcm−2 at a current density of 2 mAcm−2, which is higher than that of the GF electrode by a factor of 17.43. The EDLC device using AGF electrodes exhibits an outstanding specific areal capacitance of 1.43 Fcm−2 at a current density of 2 mAcm−2 and a favorable cycling stability retaining 90% of its initial capacitance after 2000 cycles at a current density of 20 mAcm−2. This AGF electrode fabrication method is simple, cost-effective, and eco-friendly. We believe that the fabrication of AGF electrodes may be a significant contribution to the development of high-performance supercapacitors as well as the eco-friendly energy industry.