Experimental and theoretical investigation of high-performance green-synthesized NaTiO2/AC nanocomposite as high-capacity electrodes for next-generation sodium-ion capacitors

This study presents the development of a green-synthesized NaTiO2/activated carbon (AC) nanocomposite as a high-performance electrode material for next-generation sodium-ion capacitors. Using Moringa oleifera extract, the NaTiO2/AC nanocomposite was synthesized and characterized for its electrochemical properties. The material demonstrated a high specific capacitance of 230 F/g at 5 mV/s, with excellent cycling stability, retaining 78% of its capacitance after 4000 cycles. Electrochemical impedance spectroscopy results showed a low electrolyte resistance (Re) of 13.3 Omega and a working electrode resistance (Rw) of 0.7 Omega, suggesting efficient charge transfer and ion diffusion. The nanocomposite also exhibited notable energy and power densities of 69 Wh/kg and 144 W/kg, respectively, making it a strong candidate for energy storage applications. Theoretical calculations using density functional theory further supported the experimental findings by revealing that Ti d and O p orbitals contribute to a reduced band gap of 3.134 eV, enhancing the material's electronic properties. The synergy between NaTiO2 and activated carbon significantly improves the composite's electrochemical performance, resulting in superior energy storage capabilities. These combined experimental and theoretical insights position the NaTiO2/AC nanocomposite as a promising electrode material for durable and efficient sodium-ion capacitors, contributing to the development of sustainable energy storage technologies.