Characteristics of graphite oxide membranes with different thickness by low temperature thermal reduction for aqueous EDLC electrodes and hot activation phenomenon

Abstract

Reduced graphite oxide membrane (RGOM) with different thickness were prepared and used as electric double layer capacitor (EDLC) electrodes with aqueous electrolyte. According to quantum and molecular dynamic simulations, it was difficult for K+ and OH− to diffuse into graphene sheets due to dense structure, which made the RGOM electrodes show poor EDLC behaviors. Electrochemical tests showed that controlling the thickness of electrodes and modifying the dense structure could improve the specific capacitance of EDLC. Further studies indicated that during galvanostatic charge/discharge processes, if the EDLC were heated at 70 °C for one cycle and then cooled down to room temperature, the specific capacitance could be increased further. Additionally, according to 10,000 times cycling tests at 5000 mA g−1, the improved capacitance could be maintained for long time (154–167 F g−1 during test process), indicating that the hot activation could make RGOM electrodes obtain good and stable EDLC performances.