An XAS study of the local environment of ions in soggy sand electrolytes

In this paper via X-ray absorption spectroscopy (XAS) studies we discuss the local ion environment in two different "soggy sand" electrolyte systems: RbBr in ethylene carbonate-dimethyl carbonate (EC-DMC):SiO2 and LiBr in tetrahydrofuran (THF):SiO2. The X-ray absorption near edge structure results for the RbBr in EC-DMC:SiO2 showed marked changes for the Br K-edge and almost no change for the Rb K-edge in the composite compared to the pure solution. Quantitative analysis of Br K-edge from extended X-ray absorption fine structure in LiBr in THF:SiO2 showed pronounced ordering in the Br- ions which arises from the trapping of the Br- on the surface of the silica.