Investigation of Structural, Optical, and Electrical Properties of Lithium Ion Conducting Mixed Solid Polymer Electrolyte Systems

Abstract

Mixed solid polymer electrolyte (MSPE) systems show interesting ion conduction behavior that can be exploited for practical charge storage device applications. This study focuses on the MSPE system containing Polyethylene Oxide (PEO₁: M_w = 1 $\times$ 10⁶ g/mol), (PEO₂: M_w = 1 $\times$ 10⁵ g/mol), Poly(methyl methacrylate) (PMMA: M_w = 1.5 $\times$ 10⁴ g/mol) in various weight proportions with a constant concentration of the lithium perchlorate salt. The dependence of ionic conductivity on temperature follows the Arrhenius behavior. The complex dielectric permittivity and electric modulus results reveal the sensitivity of these parameters to film composition and structural changes. X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) studies confirm significant changes in the crystallinity of the MSPE system. Bandgap studies further confirm the structural disorder in MSPE films induced due to the blending of the polymers. Sample (S2) with composition 96 wt% PEO₁–2 wt% PEO₂–2 wt% PMMA at 303 K exhibited an optimum conductivity of 1.91 $\times$ 10⁻⁴ S/cm and achieved a low activation energy of 0.3 eV which is correlated to the other parameters studied.