Oxygen vacancies on surface of the TiO2 fillers hinder Li+ conduction in PEO all-solid-state electrolyte

Polyethylene oxide (PEO) was one of the most classic and widely used solid polymer electrolyte matrixes. In this work, we added the previously synthesized titanium dioxide (B-P25) fillers with oxygen vacancies to the PEO-LiClO 4 solid electrolyte system. It is found that compared with the pristine P25 fillers, the oxygen vacancies lead to the decrease of ionic conductivity and the Li + transference number. Infrared and Raman spectroscopy shows that the introduction of oxygen vacancies lead to the formation of Li + -ClO 4 − ion pairs and the decrease of carrier concentration resulted in the decrease of Li + conductivity. Further theoretical calculations verified that this is due to the preferential combination of oxygen vacancies and ether oxygen atoms of PEO. This finding effectively supplements the effect of oxide oxygen vacancies on the conduction of Li + in the PEO matrix, and not all oxygen vacancies are beneficial to the conduction of Li + ions in the PEO matrix.