Synthesis and characterization of Ni2+-doped polypyrrole electrodes for supercapacitor application

Abstract

This study introduces a novel approach to synthesizing Ni²⁺-doped Polypyrrole (Ni²⁺-PPy) films using the Successive Ionic Layer Adsorption and Reaction (SILAR) technique—a method previously unexplored for this purpose. By leveraging the innovative integration of Ni²⁺ ions, we developed low-cost, binder-free composite materials with enhanced electrochemical properties, such as higher specific capacitance and improved cycling stability. Compared to traditional methods, this work demonstrates significant improvements in the structural and electrochemical characteristics of the synthesized films. The use of stainless-steel substrates and a simple SILAR technique enables scalable, uniform, and controllable deposition of PPy films, which offers a clear advantage over other conventional doping techniques. Characterization using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), confirms the formation of highly porous films that allow efficient ion diffusion. Electrochemical studies in 1 M H₂SO₄ using a three-electrode system reveal that Ni²⁺-PPy films exhibit a specific capacitance of 584 F/g at a scan rate of 5 mV/s, significantly higher than the 465 F/g observed for pure PPy. Additionally, the Ni²⁺-PPy films maintain 66% stability after 1000 cycles, demonstrating their superior energy storage potential. This work highlights the synergistic effects of Ni²⁺ incorporation, which improves the electrochemical performance and stability of PPy-based materials, marking an innovative step in the development of efficient supercapacitor electrodes.