Enhanced electrochemical performance of supercapattery derived from sulphur-reduced graphene oxide/cobalt oxide composite and activated carbon from peanut shells

摘要

Sulphur-reduced graphene oxide/cobalt oxide composites (RGO-S/Co3O4) were successfully synthesized by varying mass loading of Co3O4 through a simple hydrothermal method. Structural, morphological, chemical compositional and surface area/pore-size distribution analysis of the materials were obtained by using XRD, Raman spectroscopy, SEM, TEM, EDX, FTIR, XPS and BET techniques, which reveal an effective synthesis of the RGO-S/Co3O4 composites. Electrochemical performance of the materials was evaluated using a three and two-electrode system in 1 M KOH electrolyte. An optimized RGO-S/200 mg Co3O4 composite displayed the highest specific capacity of 171.8 mA h g(-1)and superior cycling stability of 99.7% for over 5000 cycles at 1 and 5 A g(-1), respectively, in a three-electrode system. A fabricated supercapattery device utilizing RGO-S/200 mg Co3O4 (positive electrode) and activated carbon from peanut shells (AC-PS) (negative electrode), revealed a high specific energy and power of 45.8 W h kg(-1) and 725 W kg(-1), respectively, at 1 A g(-1). The device retained 83.4% of its initial capacitance for over 10, 000 cycles with a columbic efficiency of 99.5%. Also, a capacitance retention of 71.6% was preserved after being subjected to a voltage holding test of over 150 h at its maximum potential of 1.45 V. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.