Tunable electrochemical properties of polyaniline/CuO/BaTiO<sub>3</sub> nanocomposites for supercapacitor application

Revolutionizing energy storage demands innovative strategies that transcend the conven­ti­onal boundaries of electrode design. Here, we unveil a powerful approach that harnesses the synergistic interplay between dielectric and conductive nanophases to unlock unprecedented charge storage performance in polymeric supercapacitors. By individually synthesizing copper oxide (CuO) and barium titanate (BaTiO3) nanoparticles and strategically embedding them into a polyaniline (PANI) matrix, we engineered two finely tuned ternary nano­composites: PCB5 (10 wt.% CuO, 5 wt.% BaTiO3) and PCB10 (5 wt.% CuO, 10 wt.% BaTiO3). Advanced structural and spectroscopic analyses (X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Ramanspectroscopy) confirmed the successful integration of the nanophases, while dielectric studies revealed distinct variations in dielectric constant and interfacial polarization behaviour depending on nanoparticle ratios. Among the composites, PCB5 showed the most balanced electrochemical performance, with a specific capacitance of 271.67 F g-¹, outperforming pristine PANI and its BaTiO3-rich counterpart. Electrochemical impedance spectroscopy further confirmed the low series and charge-transfer resistances of the PCB5 composite sample, reflecting its efficient ion/electron transport pathways. Furthermore, BET analysis showed an increased surface area (31.37 m² g-¹) compared to pristine PANI (24.08 m² g-¹), providing additional electroactive interfaces for charge accumulation. These findings establish, for the first time, a dielectric-conductive co-engineering paradigm in PANI nanocomposites, where carefully optimized filler ratios act as a dual-function booster of both dielectric constant and electrochemical kinetics. This extraordinary synergy paves the way for transformative next-generation high-energy, high-power supercapacitors with tunable multifunctionality.