Dielectric relaxation studies of poly(ethylene oxide) with the addition of salt or nanofiller

Poly(ethylene oxide) (PEO)–lithium perchlorate (LiClO4) serves as the classical model of polymer–salt systems with good polymer–salt molecular interaction at low salt concentration, whereas titanium dioxide (TiO2) without any surface treatment when added to PEO serves as a classical model of polymer–filler systems with weak polymer–filler molecular interaction. The correlation of molecular interactions of polymer–salt or polymer–filler with thermal properties of the systems, which govern the formation of morphologies of the systems, was attempted in a previous study. Hence, this work focuses on the correlation of morphologies and dielectric relaxation properties of PEO with the addition of LiClO4 or TiO2 investigated using polarized optical microscopy and electrochemical impedance spectroscopy over the frequency range from 50 Hz to 1 MHz at 25 °C. The effects of the addition of LiClO4 or TiO2 on the dynamics and relaxations of the polymer chain of PEO are discussed empirically following the fluctuation–dissipation effects from the common electrochemical terms and equivalent circuit model. The PEO–LiClO4 system seems to be one of the promising polymer electrolytes for application in lithium rechargeable batteries where the charged entities may arise from the interaction of salt with the ether oxygen of PEO in the amorphous region. Meanwhile, the PEO–TiO2 system may be analogous to a polar polymer with longitudinal dipoles along the PEO backbone, ethylene oxide monomers (from PEO) of which may represent the molecular dipole or charged entity. The findings show that the transport of charged entities in the PEO systems after the addition of LiClO4 or TiO2 is dominated by short‐range motion at room temperature. © 2022 Society of Industrial Chemistry. Possible equivalent circuits for PEO–LiClO4 and PEO–TiO2 systems and scaled imaginary parts of impedance (Z*) and electric modulus (M*) versus frequency for PEO with addition of LiClO4 or TiO2 at 25 °C.