Superionic Conduction in Rapidly Quenched Li₂S-SiS₂-Li₃PO₄ Glasses

Abstract

Lithium ion conducting glasses were prepared in the system (0.6Li₂S⋅0.4SiS₂)-Li₃PO₄ by twin-roller rapid quenching. The temperatures of glass transition (T_g) and crystallization (T_c) were determined for the glassy samples with 0-40mol% Li₃PO₄. The conductivity values at 25°C (σ₂₅) were maximized and the activation energies (E_a) for conduction were minimized at the composition with 5mol% Li₃PO₄; the maximum σ₂₅ value was as high as 9×10^-4S⋅cm^-1. Since the difference between T_g and T_c was also maximized at the same composition, it was concluded that the doping of small amounts of Li₃PO₄ improved both the glass stability against crystallization and the lithium ion conductivities.