Study of 2D layered nickel pyrophosphate using 3D Bode mapping and stability forecasting for supercapacitors

Abstract

In recent years, layered materials have gained attention in energy storage application due to their high surface to volume ratio and stable nanoarchitecture. Herein, 2D layered nickel pyrophosphate (NP) is synthesized using the hydrothermal method. The effect of annealing temperature on the electrochemical performance of the NP is discussed. Various physicochemical characterizations of the NP are carried out to understand its features. XRD confirms the NP phase of the material with the monoclinic crystal structure. Rietveld analysis is carried out to understand the structural parameters of the NP. FE-SEM shows the uniformity of 2D layered and highly porous microsheet like morphology in NP material. The detailed charge storage dynamics is analyzed using different electrochemical parameters like standard rate constant, charge transfer and diffusion coefficient. Moreover, the 3D Bode mapping measurements are carried out to obtain the in charge conduction in depth. The NP electrode shows a specific capacitance of 16382.40 mF/cm² (1820.26 µAh/cm²) at a 10 mA/cm² current density. The cyclic stability shows 99.98 % capacitance retention after 4240 cycles. Time series analysis is used to predict and forecast the cyclic stability data. Furthermore, an aqueous hybrid SC shows a specific capacitance of 667.32 mF/cm² (259.51 µAh/cm²) at a current density of 10 mA/cm² with energy and power density of 181.66 µWh/cm² and 6.48 mW/cm². All the characterization results suggest that NP can be a potential candidate for SCs.