Poly (ethylene oxide) (PEO)-based, sodium ion-conducting‚ solid polymer electrolyte films, dispersed with Al2O3 filler, for applications in sodium ion cells

Abstract

The studies on solid polymer electrolyte (SPE) films with high ionic conductivity suitable for the realization of all solid-state Na-ion cells‚ form the focal theme of the work presented in this paper. The SPE films are obtained by the solution casting technique using the blend solution of poly (ethylene oxide) (PEO) with ethylene carbonate (EC) and propylene carbonate (PC) and complexed with sodium nitrate. Structural and thermal studies of SPE films are done by XRD, FTIR spectroscopy, and TGA techniques. Surface morphology of the films is studied using the FESEM. The ionic conductivity of SPE films is determined from the electrochemical impedance spectroscopy studies. For the SPE film with 16 wt% of NaNO3 used for reacting with the polymer blend of PEO with EC and PC, the ionic conductivity obtained is around 1.08 × 10−5 S cm−1. Addition of the Al2O3 as the filler material is found to enhance the ionic conductivity of the SPE films. The studies on the Al2O3 modified SPE film show an ionic conductivity of 1.86 × 10–4 S cm−1, which is one order higher than that of the SPE films without the filler content. For the SPE film dispersed with 8 wt% of Al2O3, the total ion transport number observed is around 0.9895, which is quite impressive from the perspective of the applications in electrochemical energy storage devices. From the cyclic voltammetry studies, a wide electrochemical stability window up to 4 V is observed, which further emphasizes the commendable electrochemical behavior of these SPE films.