Synergistic effects of niobium phosphate/tungsten oxide core-shell nanocomposites for asymmetric supercapacitor

Abstract

The energy requirements of modern civilization necessitate the use of efficient renewable energies. Therefore, this research assessed the effectiveness of newly developed niobium phosphate (NbPO5)/tungsten oxide (WO3) core-shell nanocomposite thin film electrodes fabricated through a combination of facile hydrothermal synthesis with electrodeposition method as promising energy storage devices. The investigation involved a thorough analysis of the optimization of reaction time for NbPO5 to explore the resulting modifications in their structural, morphological, and energy storage properties. Raman spectroscopy offers a detailed exploration of vibrational modes and structural characteristics while, X-ray photoelectron spectroscopy (XPS) spectra provide comprehensive information on the chemical composition, elemental state, and surface properties. NbPO5/WO3 core-shell electrode presented variable surface morphologies in accordance with the different synthesis times. The optimized NbP-W-6 sample demonstrated excellent energy storage performance, with a high areal capacitance of 5.97 F/cm2 at a current density of 20 mA/cm2 and energy density of 0.406 mWh/cm2 at a power density of 7 mW/cm2. Moreover, the NbP-W-6 sample exhibited outstanding long-term cycling stability, retaining 84.63 % of its total capacitance throughout 12,000 consecutive cycles. The remarkable energy storage capacity of the NbP-W-6 is attributed to its enhanced diffusion rate, higher charge transfer efficiency, and improved carrier mobility facilitated by the core-shell structure that combines the stability of NbPO5 with the high conductivity of WO3. The assembled asymmetric pouch-type supercapacitor device (APSD) achieves an areal capacitance of 759.0 mF/cm2 at a current density of 30 mA/cm2. Through highly competitive electrochemical performance, our findings reveal that core-shell nanocomposites deposited directly onto Ni-foam, opening up potential applications in energy storage. © 2024 Elsevier B.V.