Engineered Amine-Functionalized Metal-Organic Framework to Fabricate a Composite for Next-Generation Asymmetric Supercapacitors with Ultrahigh Performance: Modulating the Energy Storage Barrier.

The present work summarizes the fabrication of an amine-functionalized cadmium-based metal-organic framework (MOF), {[Cd(AT)(BP)]·4DMF} or , by adopting a simple solvothermal approach using 2-aminoterephthalic acid (AT) as the main linker, while 4,4'-bipyridyl (BP) as an auxiliary linker. The structure of was validated by the single-crystal X-ray diffraction technique that revealed the formation of an overall three-dimensional network with BP acting as a bridge between the 2D sheets of the MOF. The robust framework of decorated with a free amine functional group was utilized for energy storage application. The electrochemical measurements of revealed a maximum areal capacitance of 9.8 mF/cm at a scan rate of 5 mV/s. Further, to enhance the practical utility of in energy storage devices, two composites of with reduced graphene oxide (rGO) and multiwalled carbon nanotubes (CNTs), viz., and , were prepared by adopting a facile ultrasonication approach. The synthesized and composites displayed an impressive areal capacitance of 117 and 37 mF/cm (58.5 and 17.5 F/g) at a scan rate of 5 mV/s, respectively, and a capacitance retention of up to 118 and 100% after 5000 cycles at a constant current density of 5 mA/cm. The highest energy density of about 4.23 mW h/cm (2.12 W h/kg) at a current density of 1 mA/cm was shown by among all the three materials attributable to the layered structure of rGO, providing a larger surface area accessible for ion adsorption. Enticed by the remarkable outcomes exhibited by , we fabricated a two-electrode asymmetric supercapacitor (ASC) device. The developed ASC device revealed energy and power densities of 26.7 mW h/cm (13.4 W h/kg) and 3760 mW/cm (1880 W/kg), respectively, with a galvanostatic charge-discharge stability of up to 10,000 cycles. The findings identify as a potential contender for future-generation supercapacitors.