In this present era, renewable energy sources and clean fuels have been very much significant. In this scenario, solar cells, wind turbines, and geothermal energy have been considered suitable alternatives to overcome the lack of energy and global warming due to fossil fuel consumption. In recent years, extensive progress in nanoscience has attracted significant attention towards energy storage devices by scientists around the world. Nafion membrane-based flexible supercapacitor may become an alternative energy storage device in the coming future. Nafion is essentially a perfluoro sulfonate proton conductor (H⁺) and contains perfluoro vinyl ether groups attached to pendant sulfonate SO₃^-H⁺ groups over a tetrafluoroethylene (Teflon) backbone. Nations are extensively used as a proton conductor for proton exchange membranes in fuel cells, water filtration, and caustic soda production. Protons on the sulfonic acid groups can ‘‘hopping’’ from one acid site to another. Nafions pores allow movement of cations but do not allow movement of anions or electrons.

The electrodes present in the upper and lower layers of IPMCs are electrical conductors with a very low electric resistivity. They are generally platinum (Pt), Gold or silver (Ag). When a continual electric current is enforced on the IPMC matrix, the positive ions, primarily at rest within the negative ionic polymer charges, move from one electrode to another. However, the negative ionic charges in the polymer are permanent; they will not be transportable. The gap between the positive and negative ionic charges will then introduce an electric field inside the IPMC matrix; there is a potential difference in its terminals and electrical forces between the IPMC systems. Metal oxides or sulfides and conducting polymers are the utmost potential electroactive materials for configuring pseudocapacitors. Conducting polymers has distinctive attribution like higher theoretical specific capacitance, good physicochemical properties, high electrical conductivity, quick large-scale production, and lower cost. An extensively analysed conducting polymer is PANI. It is a perspective electrode material for its electroactivity, higher conductivity, good stability, and specific capacitance. A proton is required for PANI to conduct and sufficiently charged and discharged to work as a Supercapacitor.

The flexible Nafion-PANI membrane was prepared in an indigenous process (the flexibility was shown in Fig1 (a)), and supercapacitor properties of that flexible membrane was investigated thoroughly. For this, a 2M solution of LiCl was prepared as the electrolyte, and electrochemical tests, namely CV, charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS), were performed at the mentioned alkaline electrolyte. The charge transfer mechanism of the Nafion-PANI membrane and bare Nafion membrane was checked by cyclic voltammetry test at different scan rates. Fig1 (b) & (c) shows the behaviour of bare Nafion and Nafion-PANI flexible membrane respectively in 2M of LiCl electrolyte at different scan rate over the range of 0–1 V. Fig1 (d) shows that the CV curve is broadened in the case of Nafion-PANI membrane as compared to bare Nafion membrane. The charge transfer is increasing in the PANI-Nafion membrane because due to the use of conduction polymer (PANI) into the Nafion membrane, the electron transfer inside the Nafion membrane increases, which further increases the cyclic voltammetry curve. Fig1 (e) shows the charge-discharge graph of the Nafion-PANI membrane. Fig1 (f) also confirms that the discharge time of the Nafion-PANI flexible membrane is greater than the bare Nafion membrane, where we take the same specific areal current in both cases.