Synergistic Effect of Activated Carbon (AC) with Halide Perovskite RbGeI3 Composite for High-Performance Supercapacitor Electrodes: A Hydrothermal Approach

Halide perovskites, known for their high ionic–electronic conductivity and flexible chemistry, have gained significant consideration in energy storage applications. In this study, halide perovskites (RbGeI3) and their composite with AC (RbGeI3/AC) were synthesized using a facile hydrothermal approach. x-ray diffraction (XRD) confirmed the successful synthesis of the composite and exhibited cubic phase structure. Field-emission scanning electron microscopy (FE-SEM) revealed porous-type morphology with high surface area. Energy dispersive spectroscopy (EDX) confirmed the desired elements such as Rb, Ge, I, and C. In electrochemical analysis, cyclic voltammetry (CV) confirmed the pseudocapacitive nature of both electrodes. An AC-based electrode displayed impressive cyclic stability and retained 86.3% of its original capacitance after 4000 successful cycles. Galvanostatic charge–discharge (GCD) testing unveiled exceptional specific capacitance of 1055.5 F/g at 0.2 A/g, high power density (590.8 W/kg), and energy density (68.6 Wh/kg). Electrochemical impedance spectroscopy (EIS) presented a small semi-circle for the AC-based composite, signifying low charge transfer resistance. We can confidently suggest that incorporation of AC with halide perovskites holds promise as a solution for advancing energy storage technology in the perspective of supercapacitor electrodes.