The mixed glass former effect in 0.35Na2O + 0.65[xB2O3 + (1-x)P2O5] glasses

Abstract

<p>Energy storage is a growing concern in an ever increasingly battery driven society. Development of safer, smaller, and longer lasting batteries is in demand. Ion conducting glasses are an important type of solid electrolyte that could be used to answer this need. Unfortunately, many known ion conducting glasses, such as binary lithium oxide glasses with conductivities in the 10-7 - 10-8 S/cm range, are not conductive enough for practical use. In order for ion conducting glasses to be used as a commercial solid electrolyte, a method of increasing the glasses' ionic conductivity must be found. While alkali mixed glass former glasses, such as Bi₂O₃+B₂O₃+LiO₂ and Li₂S+SiS₂+GeS₂, have shown increases in the alkali ion conductivity up to two orders of magnitude, the cause of this increase is unclear. This phenomena has become known as the Mixed Glass Former Effect (MGFE) and is defined by a non-linear, non-additive change in ionic conductivity. Although the MGFE has been observed in the literature, it has not been observed in all mixed glass former (MGF) glasses and has also been seen as a negative or positive effect. In this talk, I will review our comprehensive study of the physical properties, structure, and the effect of composition on MGF sodium borophosphate glasses. It is our hypothesis that changes in the short range order structures, caused by the mixing of the boron and phosphate networks, are responsible for the MGFE. I will show a strong correlation between physical properties and structural changes with changing glass former composition.</p>