XAS study on lithium ion conducting Li2O-SeO2-B2O3 glass electrolyte

Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) techniques were used to identify the local structural variations with SeO2 content for Li-ion conducting 0.5Li2O-0.5(ySeO2-(1-y)B2O3) (0.3 ≤ y ≤ 0.7) glasses. Based on the Se K-edge XAFS spectra, formation and growth of Se-O clusters were observed and also the valence state of Se cations in the glasses decreased with the increase of SeO2 content. The ratio of 3-fold coordinated boron ([3]B) to 4-fold coordinated boron ([4]B) in the glasses from the B K-edge NEXAFS spectra showed that incorporation of SeO2 in the network resulted in borate network depolymerization. The lithium ion conduction mechanism of Li2O-SeO2-B2O3 glasses was discussed in terms of the microstructural variation.