Simultaneous electrochemical preparation and reduction of graphene with low oxygen content and its electrochemical properties for high-performance supercapacitors

摘要

Graphene with low oxygen content via an electrochemically anode exfoliation is desired. Here, an electrochemical exfoliation method to realize the simultaneous electrochemical preparation and reduction of graphene with low oxygen content is proposed using a flexible graphite sheet (FGS). Under water bath, the FGS is soaked into a NaBH_4 solution under an electric field of 3 V/cm for 3,9,15 or 21 h (Gr-3/Gr-9/Gr-15/Gr-21). The C/O ratios of the FGS, Gr-3, Gr-9, Gr-15 and Gr-21 increase in turn by the X-ray photoelectron spectroscopy. The comparison between the electrochemical properties of the FGS, Gr-3, Gr-9, Gr-15 and Gr-21 indicates that the Gr-15 possesses a specific capacitance of 181 F/g and capacitance retention of 93.8% over 3000 cycles, which shows better electrochemical performances than the FGS, Gr-3, Gr-9 and Gr-21. The symmetric supercapacitor based on the Gr-15 achieves an energy density as high as 22.56 Wh/kg at a power density of 0.85 kW/kg.