Preparing electrodes with highly reduced graphene oxide load for supercapacitors by dropping-electrochemical reduction

Abstract In this work, electrodes based on reduced graphene oxide for supercapacitors are prepared via a simple and environmental friendly electrochemical reduction method. The carbon fiber felts (CFFs) with a bunch of carbon fibers (CFs) sewn in them are used as substrates to load the graphene oxide (GO) suspension, and the GO sheets loaded on the CFFs are then reduced by constant voltage method to obtain the electrode (ErGO/CFF-CFs). By studying the effect of different ErGO loadings on the electrode's performance, we can find that when the mass loading is 2.5 mg cm−2, the assembled capacitor has the best overall performance in KOH/polyvinyl alcohol (PVA) gel electrolyte. According to the two-electrode system, the capacitance of the optimized electrode can reach 334.7 mF cm−2 (133.9 F g−1) at 2 mV s−1. The specific capacitance of the device can get 167.4 mF cm−2 (33.5 F g−1) at 2 mV s−1 and the energy density of the cell can reach 20.5 μWh cm−2 (4.1 Wh kg−1) at 0.2 W cm−2 (49.3 W kg−1). Additionally, after 10,000 cycles, the device's capacitance can still maintain 96.1% of the initial capacitance. Furthermore, the testing results show that the devices also exhibit excellent electrochemical performances when H2SO4/PVA is used as electrolyte. This method can be used as a convenient route to produce electrode with large amount of rGO load.