Carbon black-intercalated reduced graphene oxide electrode with graphene oxide separator for high-performance supercapacitor

We present a general study on a high performance supercapacitor based on intercalated reduced graphene oxide with carbon black nanoparticles. Graphene oxide sheets were synthesized by oxidation and exfoliation of natural graphite and were reduced using hydroiodic acid in the presence of carbon black nanoparticles. Graphene paper was fabricated by one-step procedure via simultaneous reducing and drying the aqueous solution of mixed carbon black nanoparticles and graphene oxide on a conductive substrate. Transmission electron microscopy confirmed the intercalation of carbon black nanoparticles into reduced graphene oxide sheets, preventing them from restacking during the fabrication of paper. Results confirmed that the electrochemical performance of the reduced graphene oxide paper as a supercapacitor electrode was improved by intercalation of carbon black nanoparticles into reduced graphene oxide sheets and also the assembled supercapacitor becomes more efficient with graphene oxide separator. Cyclic voltammetry of the prepared electrodes in 30 wt% KOH solution at 10 mV/s scan rate showed that adding only 5 wt% of carbon black to graphene oxide increases specific capacitance from similar to 118 F/g to 129 F/g. In addition, the maximum specific capacitance (139 F/g) was obtained by adding 15 wt% of carbon black and that increased to 142 F/g by the use of graphene oxide paper as a separator. Furthermore, electrochemical impedance spectroscopy by Nyquist plot showed that charge transfer resistance in electrodes decreases from 18 Omega in the reduced graphene oxide to 6 Omega in the reduced graphene oxide paper with intercalated carbon black nanoparticles and ions diffusion occurs easier than previous.