Graphene Oxide-Based Fullerenes for Efficient Symmetric Configuration Supercapacitors

Abstract

Graphene nanomaterials are anticipated to enhance the specific energy-power of supercapacitors, providing a substitute to lithium-ion batteries. Herein, we investigate graphene-oxide sheet/carbon nanoparticle (GO-CNP) nanocomposites synthesized by ultrasonication of chemically synthesized GO sheets with CNPs directly derived from the GO sheets. Structural authentication revealed that CNPs act as suitable spacers, isolating the 3D GO network layers up to 3.8 sheets (single-sheet thickness: ~0.55 nm). The as-prepared nanocomposites, characterized under a three-electrode electrochemical system in aqueous solution (1 M KOH), displayed high electrochemical capacitive charge storage (97% at scan rate of 100 mV s⁻¹), very high specific capacitance (250 F g⁻¹ at 0.25 A g⁻¹ and 277 F g⁻¹ at 50 mV s⁻¹), and excellent cyclic retention (85.6% of the initial capacitance after 10 000 cycles). A GO-sheet/CNP-based symmetric supercapacitor device delivered excellent specific energy-power density of 64.8 W h kg⁻¹ and 1372.2 W kg⁻¹, respectively. Consequently, the device could power a white-emitting LED of 10 W at 2.5 V for 1 min with full brightness against a charging time of 20 s. The outstanding electrochemical properties of the nanocomposites are attributed to the disruption of GO stacking due to the presence of conductive CNPs, which facilitated ionic transport for optimized outcomes.