Electrical properties of PVA/PANI/LiI composite membranes

Abstract This study centers on polyvinyl alcohol and polyaniline films infused with lithium iodide as polymer electrolyte membranes that conduct ions for various electrochemical applications. Electrolyte membranes made from a 90:10 weight percent blend of polyvinyl alcohol (PVA) and polyaniline (PANI) were synthesized with varying amounts of LiI (from 5 to 25% by weight) via solution casting. The samples were analyzed through X-ray diffraction (XRD), Fourier transform infrared (FT-IR), mechanical properties testing, AC impedance spectroscopy, and linear sweep voltammetry (LSV). X-ray diffraction results show that the amorphous nature of PVA enhances with more additives, and LiI incorporation leads to improved mechanical properties in composite samples. FTIR analysis highlighted interactions between PVA and electrolyte components. Notably, the composites’ elongation at break surpassed that of the undoped PVA film, reaching 108 ± 7.1% with increased LiI content. The membrane containing 20 wt% LiI salt showed the highest ionic conductivity of 4.45 × 10 –3 S cm −1 . This top-performing membrane displayed an ionic transference number of 0.991 and demonstrated electrochemical stability at 2.21 V. All composite membranes displayed peaks in the dielectric loss spectra. The dielectric properties of the composites indicate a significant connection between the fluctuations in conductivity and the changes in the mobility and concentration of charge carriers. The composite materials exhibited non-Debye characteristics regarding their dielectric properties.