Structural, optical, and electrical characteristics of HPMC/PVA-I₂O₅ composites: Fabrication and performance analysis for energy storage applications

Polymer composites (PCs) are increasingly utilized in energy storage applications, notably in dielectric capacitors, due to their distinct properties and advantages over conventional liquid electrolytes. In this study, we investigate the structural, optical, electrical, and dielectric properties of hydroxypropyl methylcellulose (HPMC)/polyvinyl alcohol (PVA) composite films filled with varying concentrations of iodine pentoxide (I₂O₅), prepared via a solution casting method. Incorporating I₂O₅ into the polymer matrix significantly impacted the composite's properties. FTIR and XRD analyses revealed disturbances in molecular structure, crystallization order, and the presence of I₂O₅ crystal phases in the composite films. Calculations of crystallinity percentage indicated a reduction with I₂O₅ addition, leading to increased amorphous phase content suitable for enhancing electrical conductivity (σ). UV/vis spectroscopy studies demonstrated decreased optical energy gaps, suggesting improved charge storage capability. The σ analysis revealed enhanced values with I₂O₅ addition, indicative of improved charge mobility within the composite films. Frequency-dependent behaviors in complex permittivity (ε′ and ε″) highlighted the potential of these composites for efficient charge storage across different frequency ranges. Impedance analysis provided insights into space charges and conductive paths within the composites, influencing their electrical characteristics. Capacitors fabricated from the HPMC/PVA-I₂O₅ composites exhibited enhanced energy storage capacity and controlled conductance characteristics, demonstrating promising performance for energy storage applications. Our findings demonstrate that the HPMC/PVA-I₂O₅ composites are potential dielectric materials for capacitor technology.