Fast Ionic Transport in Solids

Abstract

The discovery of inorganic solids with ionic conductivities comparable to those of aqueous electrolytes has revolutionized solid-state electrochemistry. Sodium beta alumina, a Na⁺ conductor, and Li_xTiS₂, an intercalation compound with simultaneous Li⁺ and electronic conductivity, are two of the best and most versatile fast ionic conductors. A wide variety of cations can replace Na⁺ in beta alumina and Li⁺ in Li_xTiS₂ and change the properties of the materials. Sodium beta alumina and Li_xTiS₂ are currently used in the development of high-energy density batteries for electric vehicles and electrical utility load leveling. Current research in solid ionic conductors is exploring new intercalation compounds, solid polymer electrolytes, and alkali ion and proton transport in crystalline solids.