Enhanced asymmetric supercapacitor performance using 2D Ni2P2O7 nanoplates with high specific capacitance

Nickel pyrophosphate (NiP) electrodes were produced via a hydrothermal method for supercapacitor applications. The structural properties of the prepared samples were thoroughly investigated using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). FESEM and TEM were used to assess the morphological growth. The prepared NiP samples exhibited a well-defined two-dimensional (2D) nanoplate architecture with linked porosity networks, which provide numerous electroactive sites and facilitate efficient ion diffusion and quick electron transport. Additionally, specific surface area of all the prepared samples were carried out by using BET analysis. The optimized NiP electrode achieved a high specific capacitance of 1054 F/g at 5 mA/cm 2 current density and 80.82% capacitance retention after 5000 cycles. An asymmetric device fabricated with PVA-KOH gel electrolyte delivered a capacitance of 121 F/g, with an energy density of 36 Wh/kg and power density of 4800 W/kg. EIS confirmed the NiP-9 electrode's superior charge transport, showing low resistances, a short relaxation time and enhanced ionic conductivity. These results highlight NiP electrodes as promising, scalable materials for high-performance, sustainable supercapacitors and future energy storage technologies. • Nickel pyrophosphate (NiP) electrodes were synthesized via the hydrothermal route. • FESEM shows porous 2D nanoplates with more active sites and efficient ion transport. • The optimized NiP-9 electrode exhibited a specific capacitance of 1054 F/g at 10 mA cm −2 . • Excellent cycling stability, with 80.82% retention after 5000 cycles. • The asymmetric device achieved a specific capacitance of 121 F/g.