Ion-conducting polymer electrolyte based on poly(ethylene oxide) complexed with Li1.3Al0.3Ti1.7(PO4)3 salt

Solid polymer electrolyte films were prepared from poly(ethylene oxide) (PEO) and fine Li1.3Al0.3Ti1.7(PO4)3 salt in appropriate ratios of EO/Li ratios (=8-50) by a solution-cast technique. The complexation of Li1.3Al0.3Ti1.7(PO4)3 salt with PEO was directly detected by infrared (IR) spectroscopy. A cellular structure formed by the PEO crystallites covered by the amorphous complexed layer was observed under SEM. Differential scanning calorimetry (DSC) showed that in the polymer electrolyte, the PEO crystallization temperature decreased from 63.67 to 52.64 °C with the addition of increasing Li1.3Al0.3Ti1.7(PO4)3. The room temperature impedance spectra of the polymer films all exhibited a shape of depressed semicircle in high frequency range and an inclined line in low frequency range, but the high temperature ones were mainly the inclined lines. Measurements of ionic conductivity in the temperature range 298-383K showed that, with EO/Li = 16, the conductivity of the film is ∼10−6 S cm−1 at room temperature and ∼10−4 S cm−1 at above 343 K. By the combining EIS measurement of fabricated solid-state electrochemical cells, the transference number data shows that the polymer films was a mixed (ionic + electronic) conductor, and that the charge transport in the polymer electrolyte system was predominantly due to ions.