Electrochemical evaluation of anodic galvanized-iron nanoparticles as electrode materials for supercapacitors

Abstract

Electrode materials with excellent electrochemical features are essential for high-performance supercapacitors (SCs). This study explores galvanized iron (GI), a low-cost and naturally abundant material, as an innovative electrode platform for SC applications. GI (zinc coated iron) was anodized in an environmentally benign electrolyte, which produced α-Fe₂O₃ nanoparticles (NPs). The structural and compositional properties of the α-Fe₂O₃ material were investigated using X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The electrochemical performance was evaluated through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The anodic GI electrode demonstrated enhanced electrochemical kinetics and achieved a high specific capacitance (C_s) of 694 F g⁻¹ at a current density of 2 A g⁻¹, significantly higher than the pure anodic iron oxide NPs. An asymmetric supercapacitor (ASC) device assembled from anodic GI (α-Fe₂O₃) NPs as the positive electrode and activated carbon (AC) as the negative electrode delivered a C_s of 132 F g⁻¹ at 2 A g⁻¹, with an energy density of approximately 22.18 Wh kg⁻¹ at a power density of ∼1093 W kg⁻¹. Notably, the device retained ∼94% of its initial capacitance after 7000 charge–discharge cycles, demonstrating excellent long-term stability.