Structural and Electrochemical Characterization of Na2CO3/ γ- Al2O3 Electrodes for Supercapacitor

The development of electrode materials with suitable structural and surface properties is crucial for improving electrochemical energy storage systems. Gamma alumina (𝛾-Al2O3) has attracted considerable interest in electrochemical research due to its unique structural and surface properties. However, its charge-storage capacity is still limited, highlighting the need for structural and compositional modifications to improve its electrochemical performance. In this study, Na2CO3 was introduced into 𝛾-Al2O3 as a sodium precursor to induce phase modification and enhance the electrochemical activity. The systematic incorporation of Na2CO3 also provides an opportunity to elucidate the relationship between compositional changes, structural evolution, and electrochemical response. 𝛾-Al2O3 was modified with different Na2CO3 contents (0, 10, 20, and 30%) through a solution-based mixing method. XRD results indicate that Na2CO3 addition affects the γ-Al2O3 structure and promotes the formation of a secondary NaAlO2 phase. SEM analysis reveals an increase in particle size and porosity with increasing Na2CO3 concentration, with porosity increasing from 42.37% to 48.38%. The CV profiles exhibit quasi-rectangular characteristics, indicating a pseudocapacitive contribution arising from redox reactions occurring at the electrode surface. Increasing Na2CO3 concentration also reduces the Rs and Rct, reaching 13.37 Ω and 49.67 Ω, respectively, at 30% Na2CO3. GCD measurements show that the specific capacitance increases from 2.737 to 7.844 F g-1, while the energy density and power density reach 1.151 Wh kg-1 and 27.045 W kg-1, respectively. Among the compositions studied, the electrode with 30% Na2CO3/ -Al2O3 showed the improvement in electrochemical properties.