Defect-Driven Enhancement of Supercapacitive Performance in γ-Irradiated NaNbO3 Perovskite Ceramics
Abstract
Introducing controlled defects into perovskite oxides is increasingly being explored as a viable route toward improving the performance of modern supercapacitors. In the present work, γ(γ)-irradiation-induced defect modulation was employed to enhance the electrochemical properties of NaNbO3 (NN) ceramics synthesized through ball-milling-assisted solid-state reaction route. Prepared samples were exposed to 60Co γ-radiation at a dose of 100 kGy, resulting in significant modifications in their structural, chemical, and electrochemical characteristics. The γ-irradiated NaNbO3 (NNG) electrode exhibited remarkable electrochemical enhancement compared with pristine NN, delivering a 226 F g–1 specific capacitance at 0.5 A g–1 in 6 M KOH electrolyte. Cyclic voltammetry and galvanostatic charge–discharge analyses confirmed pronounced pseudocapacitive behavior with improved charge storage capability after irradiation. Electrochemical impedance spectroscopy revealed reduced charge transfer resistance and enhanced ion diffusion kinetics in the irradiated sample, attributed to irradiation-induced defects and improved electrochemically active surface sites. Kinetic investigations based on Dunn’s model and power-law analysis demonstrated a combined charge storage mechanism involving both diffusion-controlled and capacitive contributions, with diffusion-driven Faradaic reactions dominating the overall process. Furthermore, the NNG electrode exhibited exceptional long-term stability, achieving ∼116% capacitance retention with ∼100% coulombic efficiency after 10,000 charge–discharge cycles, indicating self-activation process during prolonged cycling. Enhanced electrochemical performance is primarily associated with γ-irradiation-induced defect engineering, which promotes faster electron/ion transport and improved electrochemical accessibility within the perovskite framework. This study highlights γ-irradiation as an effective and facile approach for tailoring perovskite oxides and establishes defect-engineered NaNbO3 as a promising electrode material for advanced supercapacitor applications.