Cobalt-based metal-organic framework/nickel-cobalt sulphide composite nanopetal arrays for high-performance hybrid coin cell supercapacitor

Affordable, environmentally friendly, and straightforward techniques, such as chemical bath deposition and electrodeposition, were employed to create a composite material consisting of cobalt metal-organic framework (Co-MOF) and nickel cobalt sulfide (NCS) on a nickel foam substrate. Comprehensive characterization was carried out to assess the resulting binder-free electrodes' structural, morphological, and electrochemical properties, including Co-MOF, NCS, and the Co-MOF/NCS composite. Morphological analysis revealed a highly ordered, porous, interconnected nanostructure resembling petal-like arrays in the Co-MOF/NCS composite. Notably, the electrochemical performance of the Co-MOF/NCS composite surpassed that of both pristine Co-MOF and NCS. It achieved the highest areal capacitance of 1.59 F/cm² at 1 mA/cm² current density. Furthermore, the Co-MOF/NCS composite demonstrated remarkable cyclic stability and capacity retention, preserving 83.80 % of its capacity after 15,000 cycles and 89.58 % after 10,000 cycles. The exceptional electrochemical behavior can be attributed to the unique nanopetal structure, which promotes the intercalation of electrolyte ions, provides numerous active sites, and ensures good electrical conductivity. A hybrid asymmetric coin cell supercapacitor was constructed to highlight its practical utility in energy storage. It uses Co-MOF/NCS nanopetal arrays as the positive electrode and an activated carbon film as the negative electrode. The fabricated asymmetric coin cell supercapacitor exhibited outstanding electrochemical performance, achieving a high energy density (E_D) of 0.215 mW/cm² (38.47 Wh/kg) at a power density (P_D) of 1.778 mW/cm² (3175.3 W/kg), with a retention capability of 88.07 % over 10,000 cycles.