Tailored nanoarchitectonics of PPy/g-C3N4/MnO2 hybrid on NiCo LDH for enhanced energy storage in supercapacitors

Abstract

The growing demand for efficient energy storage devices holding high specific energy has accelerated the search for advanced electrode materials. Transition metal-based layered double hydroxides (LDHs), particularly those containing nickel (Ni) and cobalt (Co), have emerged as promising candidates due to their tunable layered structure and chemical composition. In this study, LDH and its hybrids were prepared using a simple hydrothermal technique. In addition, X-ray diffraction (XRD) measurements approve the presence of H₂O molecules and carbonate anions in the interlamellar space due to their extended interlayer spacing. The quaternary NiCo LDH/manganese dioxide (MnO₂)/polypyrrole (PPy)/graphitic carbon nitride (g-C₃N₄) hybrid nanocomposite exhibits a specific capacitance of 2389 F/g at 1 A/g, with 88 % retention after 5000 cycles at a higher current density of 10 A/g. The superior electrochemical performance is accredited to reduced aggregation and enhanced electronic conductivity. Charge storage kinetics were analysed using Dunn's method and power law, reveals increased diffusive contribution in the quaternary nanocomposite. A hybrid supercapacitor device was fabricated using quaternary hybrid as cathode and activated carbon (AC) as anode delivers a high specific capacitance of 260 F/g at 1 A/g, with 95 % cyclic stability after 10,000 cycles. The assembled device achieves a specific energy of 82 Wh/kg at a specific power of 750 W/kg and a coulombic efficiency of 99 %, demonstrating excellent potential for energy storage applications.