High-rate supercapacitor using magnetically aligned graphene

Graphene has been widely used as an electrode material for supercapacitors. However, parallelly-stacked graphene layers often result in inefficient ion diffusion and electron transfers that usually reduce the rate capability of a supercapacitor. In this study, reduced graphene oxide (rGO) and poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) composite films were prepared by a solvent evaporation method using PEDOT: PSS as the binder to fix aligned graphene for its good conductivity and strong pi-pi stacking interactions with the graphene sheets. Analyses using scanning electron microscopy (SEM), nitrogen adsorption-desorption, and small-angle X-ray scattering show that the graphene sheets were well aligned when a magnetic field was applied, though they were oriented randomly without the magnetic field. As a capacitor electrode material, the aligned rGO shows a specific capacitance of 169 F g(-1) with a capacitance retention of about 70% at a current density of 50 A g(-1) and its cyclic voltammetry (CV) loops maintained a rectangular shape at a voltage scan rate of 2 V s(-1). The aligned rGO electrode can help break through the limitations of traditional supercapacitors and increase significantly their charge/discharge rate and power density.

Automated summary

Graphene has been widely used as an electrode material for supercapacitors, but the parallel-stacked layers often result in inefficient ion diffusion and electron transfers. By aligning reduced graphene oxide (rGO) using a magnetic field, the electrode showed improved specific capacitance and performance, breaking through the limitations of traditional supercapacitors. This study highlights the potential of aligned rGO to increase the charge/discharge rate and power density of supercapacitors significantly.