In situ grown synergistic Co-based metal–organic framework/graphene oxide composite for enhanced supercapacitor performance

Abstract

The use of pristine metal–organic frameworks (MOFs) as active electrodes for energy storage is challenging in practice due to their low conductivity and electrochemical durability. To increase the energy storage performance of the pristine MOF, an in situ graphene oxide (GO) composite of a cobalt succinate MOF (abbreviated as Co-MOF) is designed using cheap, commercially available starting materials for an energy storage electrode. Herein, we demonstrate the MOF-GO composites with GO weight percentages of 5% (Co-MOF-GO5) and 10% (Co-MOF-GO10) to elucidate the potential of these composites for high-performance supercapacitors. Among them, Co-MOF-GO5 exhibits the highest specific capacitance of 552 F g⁻¹, with excellent cycle stability over 5000 cycles and improved energy density (33 W h kg⁻¹) and power density (2.9 kW kg⁻¹) in a three-electrode cell system compared with those of pristine Co-MOF and other composites. The calculated electrochemically active surface area (ECSA) and lower charge transfer resistance also support the better performance of Co-MOF-GO5 compared with Co-MOF-GO10. To assess the practical applicability of Co-MOF-GO5 as an energy storage material, symmetric CR2032 coin-cell devices were fabricated using Co-MOF-GO5 at both electrodes with an aqueous KOH electrolyte. These devices can power a commercially available light-emitting diode bulb (∼1.8 V) for a few minutes.