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 Ω and a working electrode resistance (Rw) of 0.7 Ω, 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.