Characteristics of a Li₃BS₃ Thioborate Glass Electrolyte Obtained via a Mechanochemical Process

To improve the ionic conductivity of solid electrolytes, it is generally thought that anions with high polarizability should be used. However, the relationship between polarization and conductivity is not clear because conductivity largely depends on the crystal structure. In this study, we focus on amorphous materials with no long-range ordered structure. The conductivity and ductility properties of lithium boron oxide (Li3BO3), lithium boron nitride (Li3BN2), and lithium boron sulfide (Li3BS3) are compared. Li3BS3 glass is prepared from Li2S, B, and S using heat treatment and a mechanochemical process. It has high ductility and a higher ionic conductivity (3.6 × 10–4 S cm–1 at 25 °C) than that of Li3BO3 and Li3BN2 glass with a low activation energy of 32 kJ mol–1. Li3BS3 glass is therefore suitable as an ionic conductor with high conductivity. The electronegativity of anions and glass properties such as ionic conductivity and ductility are correlated, and it is proposed that this relationship can be used as a basis for investigating fast ionic conductors.