UV-assisted synthesis of an Ag-poly (aminosalicylic acid) hybrid system for an asymmetric supercapacitor and its application as a low pass filter

Supercapacitors have attracted substantial research interest as energy storage devices because of their long cycle life, quick electrochemical charging-discharging process and high energy and power densities. In this study, a UV-light mediated synthesis route was applied to fabricate a silver-polymer (poly-aminosalicylic acid) [Ag-PASA] hybrid system as a cathode material for the preparation of an asymmetric supercapacitor. In a three-electrode setup, Ag-PASA as an active material displayed a specific capacity of 317 C g⁻¹ at 5 mV s⁻¹ in the presence of KOH (1 mol dm⁻³) as an electrolyte. The assembled asymmetric device fabricated using Ag-PASA as a cathode material and activated carbon as an anode material exhibited a faradaic charge storage mechanism, achieving a specific capacity of 55 C g⁻¹ at 5 mV s⁻¹ and a capacity retention of 85% after 10⁴ charge-discharge cycles at 1.4 A g⁻¹. The device delivered specific energy values of 9 and 15.1 W h kg⁻¹ at specific powers of 1625 and 325 W kg⁻¹, respectively. Electrochemical results indicate that Ag-PASA could be an excellent cathode material for asymmetric supercapacitor applications. The fabricated supercapacitor was applied in an RC circuit to analyse its frequency response through both experimental and simulation methods. The results demonstrated an effective attenuation of high-frequency components, confirming a cut-off frequency of 3 Hz, which is critical for low pass filter application in audio processing and signal conditioning.