Zinc Chloride–Polyethylene Oxide Gel Polymer Electrolytes for Wearable and Flexible Energy Storage Applications

ABSTRACT We prepared and evaluated the properties of hydrated ZnCl 2 ‐Polyethylene oxide (PEO) gel polymer electrolyte (H‐GPE) for flexible electrochemical capacitors (FEC). The FEC was developed using the H‐GPE and a multi‐layer graphene sheet as an electrode for wearable and flexible energy storage applications. The electrochemical performance of the fabricated H‐GPEs with different ZnCl 2 :PEO ratios were evaluated. Three compositions, namely 60:40, 70:30, and 80:20 wt.%, were investigated and denoted as FEC1, FEC2, and FEC3, respectively. Among these, the FEC2 sample exhibits comparatively higher specific capacitance (7.374 µF.cm −2 ) values compared to FEC1 (5.840 µF.cm −2 ) and FEC3 (2.280 µF.cm −2 ) at a current density of 0.2 µA.cm −2 . The device developed with 70% ZnCl 2 exhibited the highest specific capacitance among the tested compositions, indicating the most favorable overall electrochemical behavior, consistent with the combined FTIR and electrochemical results. Further, the electrochemical performance of FEC2 is examined at various temperatures (−10 to 50°C), and it reveals that the specific capacitance of FEC increases with temperature. The mechanical flexibility studies show that the current response decreases as the bending angle increases, from 30° to 180°. The observed performance reveals the possible application of this H‐GPE along with new active electrode materials in FEC devices for low‐powered electronics.