Preparation and electrochemical behaviors of composite solid polymer electrolytes based on polyethylene oxide with active inorganic–organic hybrid polyphosphazene nanotubes as fillers

Abstract

Inorganic–organic hybrid porous poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanotubes with active hydroxyl groups are incorporated in polyethylene oxide (PEO), using LiClO₄ as doping salts, to form a novel composite polymer electrolyte (CPE). The composite solid polymer electrolytes are characterized using differential scanning calorimetry (DSC), atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrical impedance spectroscopy. The SEM photographs indicate that the electrolytes are miscible and homogeneous. Incorporation of active PZS nanotubes in PEO–LiClO₄ polymer electrolytes facilitates salt dissociation and enhances ionic conductivity. Maximum ionic conductivity values of 4.5 × 10⁻⁵ S cm⁻¹ at ambient temperature and 1.56 × 10⁻³ S cm⁻¹ at 80 °C are obtained when the content of active PZS nanotubes is 10 wt% and the lithium ion transference number is 0.39. The experiment results show that the inorganic–organic hybrid polyphosphazene nanotubes with active hydroxyl groups can enhance the ionic conductivity and increase the lithium ion transference number of PEO-based electrolytes more effectively comparing with traditional ceramic fillers such as SiO₂.