NiO/g-C3N4/PANI/Ni-metal-organic framework composite for high-energy supercapacitor electrodes

Abstract

This work is prioritized in tuning the capacitive performance of nanostructured nickel-metal-organic framework (Ni-MOF) as a high-performance electrode material for supercapacitors. The enhancement in performance is conducted by choosing a material combination that includes a metal oxide, carbonaceous, and conductive polymer comprising nickel oxide/graphitic carbon nitride/polyaniline. The material coupling is carried out by a simple reflux method using benzene-1,4-dicarboxylic acid as an organic ligand. Various characterization tools are used to confirm structural, chemical, electronic, thermal, and morphological properties. The tuned quaternary composite, nickel oxide/graphitic carbon nitride/polyaniline/Ni-MOF, exhibited a battery-type storage mechanism delivering a high specific capacitance (specific capacity) of 2,420 F/g (584 mAh/g) at the current density of 5 A/g, with a specific capacitance retention ability of 75% at 20 A/g. A kinetic study using a rotational disk electrode is carried out, and the highest diffusion coefficient of 8.64 × 10−9 cm2/s is obtained. In the fabrication supercapacitor, the quaternary composite delivered an energy density of 31.3 Wh/kg at a power density of 1,491 W/kg. It was found to be 1.5 times more than the ternary-based supercapacitor. Finally, stability tests were carried out, and the fabricated supercapacitors reached 99.5% stability even after 3,000 charges and discharges. For practical application demonstration, Swagelok cells are manufactured and charged to glow with different color light-emitting diode lights. This work brings a clear path to developing MOF-based composites for high-energy storage applications.