Exploring the microstructural properties of hydroxypropyl‐methylcellulose‐based solid polymer electrolytes: a promising candidate for flexible electrical double‐layer capacitor

Abstract This study investigates the development and characterization of solid polymer electrolytes based on hydroxypropyl methylcellulose (HPMC) for magnesium ion transport. Electrolyte films were prepared using a conventional solution casting technique, incorporating HPMC and magnesium acetate. Fourier transform infrared (FTIR) spectroscopy and XRD analyses were conducted to examine the interactions between the polymer and salt components. Impedance spectroscopy was employed to assess the electrical conductivity of the prepared electrolytes. Thermal stability was evaluated using TGA. The FTIR and XRD results indicated the formation of a complex between the polymer and salt. The electrolyte containing 30 wt% magnesium acetate exhibited a room temperature ionic conductivity of 5.88 × 10 −4 S cm −1 , demonstrating enhanced electrical properties. An electrical double‐layer capacitor was fabricated using this high‐conductivity electrolyte, and its electrochemical performance was analysed. © 2025 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.