Title : Synthesis, characterization, and electrochemical performance of Mg-Co MOFs for supercapacitor applications
Abstract:
Supercapacitors offer high power density and fast charging, but are limited by low energy capacity and stability issues. Metal-organic frameworks (MOFs), with their large surface area and rich redox-active sites, provide a promising solution for significantly enhancing their performance. In this study, MgXCo1-X-MOFs were synthesized using a facile microwave-assisted method. The synthesis approach plays a critical role in shaping the microstructure, surface morphology, and overall uniformity of the supercapacitor electrode materials. XRD, FT-IR, SEM, EDX, and UVvis techniques were used to characterize the structural, morphological, and physicochemical properties of MgXCo1-X-MOFs for supercapacitor applications. Electrochemical investigations, including galvanostatic charge-discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), were carried out to assess the performance of MgXCo1-X-MOFs electrodes with different Mg/Co ratios. Among the compositions studied, the Mg0.4Co0.6-MOFs exhibited superior electrochemical behavior, delivering specific capacitances of 299.84 F g-¹ at 0.5 A g-¹. In addition, the electrode showed excellent cycling stability, retaining 99.09% of its initial capacitance and achieving coulombic efficiencies of 99.81% after 5000 cycles at 6 A g-¹. The best-performing Mg0.4Co0.6-MOFs were used as positive electrodes, while activated carbon (AC) was used as negative electrodes to assemble asymmetric supercapacitor devices. The Mg0.4Co0.6-MOFs//AC device achieved an energy density of 31.9 Wh kg-¹ and a power density of 720 W kg-¹ at 0.3 A g-¹ while delivering a specific capacitance of 159.3 F g-¹. The device retained 78.65% of its initial capacitance and gave a Coulombic efficiency of 98.86% after 5000 cycles at 2 A g-¹. Overall, these results highlight the bimetallic MgXCo1-X-MOFs as promising electrodes for high-performance asymmetric supercapacitors.
Keywords: Asymmetric supercapacitor, Bimetallic electrodes, Energy density, Metal-organic frameworks (MOFs), Microwave-assisted synthesis.
