Design and development of a porous nanorod-based nickel-metal-organic framework (Ni-MOF) for high-performance supercapacitor application

Metal-organic frameworks have received increasing attention as promising electrode materials in supercapacitors. In this study, we synthesized a nickel-metal-organic framework (Ni-MOF) by a simple and low-cost reflux condensation technique using non-hazardous trimesic acid as an organic ligand. The structures and morphologies of the Ni-MOF material were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy techniques. The prepared Ni-MOF was found to have a rod-like morphology and these morphologies can provide beneficial paths for electrolyte ion penetration, obtaining an enlarged contact area between the active material and electrolyte. The Ni-MOF had a considerable specific surface area of 398.4 m(2) g(-1). Further, its highly porous structure offered excellent supercapacitor performance. The charge-storage mechanism of the electrodes was investigated by cyclic voltammetry, charge-discharge cycling, and electrochemical impedance spectroscopy using 2 M KOH as an electrolyte in a three-electrode assembly. The specific capacitance of the Ni-MOF was found to be 1956.3 F g(-1) at a current density of 5 mA cm(-2) by GCD studies and it retained 81.13% of its initial capacitance even after 3000 GCD cycles at a 35 mA cm(-2) current density. An as-fabricated Ni-MOF//activated carbon hybrid supercapacitor (HSC) exhibited a specific energy of 98.15 W h kg(-1) at a specific power of 1253.47 W kg(-1) and excellent capacity retention of 99.29% over 3000 cycles. The results of this study imply a great potential of the Ni-MOF for application in efficient and sustainable energy-storage devices.