Design and synthesis of a MnCo-MOF modified flexible 3D graphene sponge electrode for an asymmetric supercapacitor with high power and energy density

Abstract

Recently, 3D materials such as graphene sponges with metal–organic frameworks (MOFs) have received a lot of attention as electrodes in energy storage devices. The porous skeleton structure of both graphene sponge and MOFs facilitates the transport of electrolytes and metal ions in the MOF, increasing the active surface area. In this study, an electrode with high capacitive performance was designed by combining a 3D flexible graphene sponge (3DG) with a MnCo-MOF nanostructure. The as-prepared MnCo-MOF/3DG exhibited a capacitive performance of 4086 F g⁻¹ at 1 A g⁻¹ and maintained 83% of its initial capacitance value after 10 000 cycles. Additionally, an asymmetric supercapacitor with high energy density was developed successfully using MnCo-MOF/3DG as the positive electrode and 3DG as the negative electrode. This MnCo-MOF/3DG//3DG circuit with stable EDLC behavior showed a high specific capacitance of 2383 F g⁻¹ at 1 A g⁻¹ and excellent cycling durability with 92% specific capacitance retained even after 10 000 cycles. The designed flexible asymmetric supercapacitor circuit demonstrated remarkable electrochemical performance with a high energy density of 198.5 W h kg⁻¹ and a power density of 5823 W kg⁻¹ as well as excellent mechanical flexibility and cycling stability. The efficient fabrication of MnCo-MOF-modified flexible 3D graphene sponge electrodes with remarkable performance will open a new avenue for potential applications in flexible electronics.