Fast Lithium Ion Conduction in Li₂SnS₃: Synthesis, Physicochemical Characterization, and Electronic Structure

Li₂SnS₃ is a fast Li⁺ ion conductor that exhibits high thermal stability (mp ∼750 °C) as well as environmental stability under ambient conditions. Polycrystalline Li₂SnS₃ was synthesized using high-temperature, solid-state synthesis. According to single-crystal X-ray diffraction, Li₂SnS₃ has a sodium chloride-like structure (space group <i>C</i>2<i>/c</i>), a result supported by synchrotron X-ray powder diffraction and ¹¹⁹Sn Mössbauer spectroscopy. According to impedance spectroscopy, Li₂SnS₃ exhibits Li⁺ ion conductivity up to 1.6 × 10^–3 S/cm at 100 °C, which is among the highest for ternary chalcogenides. First-principles simulations of Li₂SnS₃ and the oxide analogue, Li₂SnO₃, provide insight into the basic properties and mechanisms of the ionic conduction. The high thermal stability, significant lithium ion conductivity, and environmental stability make Li₂SnS₃ a promising new solid-state electrolyte for lithium ion batteries