Tuning diffusion coefficient, ionic conductivity, and transference number in rGO/BaCoO ₃ electrode material for optimized supercapacitor energy storage

Due to their remarkable cycle stability and outstanding capacitance, ABO₃-type perovskite materials have emerged as highly effective electrode materials, delivering remarkable electrochemical performance. In this study, BaCoO₃/rGO composites with varying rGO content (0, 5, 10, and 15%), designated as PBCO, BCO-I, BCO-II, and BCO-III, were synthesized using a solvothermal process. These composites were evaluated for their potential as electrode materials in supercapacitor (SC) applications. X-ray diffraction analysis confirmed the presence of well-crystallized samples with a hexagonal phase structure. Field emission scanning electron microscopy revealed the desired level of porosity, well-defined morphologies, and uniformly distributed grains, which are beneficial for electrochemical applications. Elemental analysis verified the stoichiometric composition of the samples. Comprehensive electrochemical characterization was performed using cyclic voltammetry in a 2 M KOH solution, revealing a transition from diffusive control (EDLC) to hybrid capacitor behavior. Additionally, galvanostatic charge-discharge experiments demonstrated that the BCO-III composite exhibited a specific capacity of 90.15 C g⁻¹, an energy density of 21.28 W h kg⁻¹, and a power density of 531.25 W kg⁻¹. The transference number (t ₊) is found to be 0.2, which means that higher current will be driven through the anion. Further, the sample BCO-III, exhibiting the highest specific capacity, was evaluated for stability and demonstrated a remarkable retention rate of 90% after 5k GCD cycles and a remarkable coulombic efficiency of 94%, with an excellent diffusion rate and ionic conductivity of about 4.51 × 10⁻¹⁴ cm² s⁻¹, 0.128 S cm⁻¹, respectively, highlighting its significant potential for SC applications.