Plasma-assisted fabrication of PPy-Ni(II) hybrid electrodes for high-performance supercapacitors with enhanced capacitance and voltage window

Abstract The integration of plasma-engineering techniques in energy storage devices has emerged as a promising strategy to enhance the electrochemical behavior of electrode materials. In this study, a novel hybrid system comprising polypyrrole (PPy) and a bis(oxamato) nickel(II) complex ([nBu4N]2[Ni(opba)]) was developed and modified through plasma surface treatment to improve its capacitance, conductivity, and electrochemical stability. Plasma-modified stainless steel mesh substrates provided enhanced surface energy and active nucleation sites for the electropolymerization of PPy, resulting in a three-dimensional, highly porous structure favorable for charge transport and ion accessibility.Electrochemical analysis, including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS), revealed a significant improvement in the specific capacitance (up to 160 Fg^-1 at 1 Ag^-1), and a widened potential window (up to 1.5 V), with 97% capacitance retention over 1000 cycles. These results confirm that the synergistic combination of plasma-induced morphology control and redox-active metal complex enhances both energy and power density of the supercapacitor.This work represents a case study to demonstrate the influence of Dielectric Barrier Discharge (DBD) plasma treatment under selected parameters on PPy–Ni(II) hybrid electrodes, rather than a systematic optimization across different plasma conditions. This method provides a scalable and sustainable pathway for the development of high-performance capacitors, especially for applications under harsh plasma or space environments.