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

Abstract

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 m² 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.