Electrolyte-driven performance of optimized polyaniline–cobalt tungstate for supercapacitors

We present a novel class of nanostructured electrode materials using polyaniline (PANI) doped with ultralow concentrations (< 10 wt%) of cobalt tungstate (CoWO₄), which were manufactured using a polyol-mediated method in the quest for next-generation energy storage technologies. This work offers the first thorough comparison of PANI/CoWO₄ nanocomposites in acidic (H₂SO₄), neutral (KCl), and basic (KOH) electrolytes, demonstrating unique ion–electrode interactions controlled by ionic size and protonation dynamics. Structural and advanced spectroscopic analyses—encompassing XRD, TEM, SEM–EDX, LIBS, and XPS—confirmed the successful integration of CoWO₄ into the polymeric matrix with enhanced crystallinity (up to 57.4%) and uniform nanoscale dispersion (13–27 nm). FTIR and Raman spectroscopy further evidenced strong Co–O and W–O vibrational modes, indicating chemical interaction with the PANI backbone. The electrochemical performance was systematically investigated in acidic (1 M H₂SO₄), neutral (1 M KCl), and alkaline (1 M KOH) electrolytes via cyclic voltammetry, galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). All composites exhibited improved capacitive behavior over pristine PANI, with the 8 wt% CoWO₄–PANI composite delivering the highest specific capacitance of 243.2 F/g and energy density of 30.5 Wh/kg in 1 M H₂SO₄. Acidic media facilitated superior redox activity and ionic conductivity, while neutral electrolytes extended the stable potential window. This work highlights the combined contributions of conductive polymer and pseudocapacitive metal tungstate, establishes optimal dopant concentration, and elucidates electrolyte-dependent behavior. The findings offer a scalable and cost-effective pathway for engineering high-performance electrode materials tailored for next-generation energy storage systems.