Iron-Cation–Integrated Polyaniline Electrodes for High-Performance Coin-Cell Hybrid Supercapacitors

Polyaniline (PANI) is commonly used as an electrode material for supercapacitors; nevertheless, it has limited conductivity, leading to significant IR drops during charging and discharging. To enhance its performance, PANI was integrated with iron (Fe), a non-toxic and abundant element, creating a composite electrode. The electrochemical performance of the PANI/Fe composite, produced via direct electrodeposition, was compared to pure PANI in a 3-electrode system with 1 M H₂SO₄ electrolyte at 0.7 V vs Ag/AgCl. The PANI/Fe composite exhibited significantly reduced IR drops, suggesting improved conductivity due to the interaction between PANI and Fe cations. It achieved a specific capacitance of 278.7 F g⁻¹, double that of pure PANI (137.7 F g⁻¹). A hybrid supercapacitor, with PANI/Fe positive electrode and jute-stick activated carbon (JAC) negative electrode, was also tested. This device delivered a specific power of 479.5 W kg⁻¹, specific energy of 62.9 Wh kg⁻¹, and specific capacity of 131.2 mAh g⁻¹ at 1 A g⁻¹, with a cell potential of 1.2 V. After 4000 cycles at 10 A g⁻¹, it retained 97% of its capacity, with peak values of 6600 W kg⁻¹ power and 26.6 Wh kg⁻¹ energy. These results demonstrate the potential of Fe-enhanced PANI for improved supercapacitor performance.