Lithium Chalcogenidotetrelates: LiChT—Synthesis and Characterization of New Li⁺ Ion Conducting Li/Sn/Se Compounds

Five new lithium chalcogenidotetrelates, so-called “LiChT” phases, with the elemental combination Li/Sn/Se, Li 4 [SnSe 4 ] ( 1 ), 1 ∞ {Li 2 [SnSe 3 ]} ( 2 ), and the respective solvates Li 4 [SnSe 4 ]·13H 2 O ( 3 ), Li 4 [Sn 2 Se 6 ]·14H 2 O ( 4 ), and Li 4 [SnSe 4 ]·16MeOH ( 5 ) were generated in single-crystalline form. We present and discuss syntheses, crystal structures, spectroscopic and thermal behavior, as well as Li + ion conducting properties of the phases that represent uncommon Li + ion conducting materials with a maximum conductivity found for 1 (σ 20°C = 2 × 10 –5 S·cm –1, σ 100°C = 9 × 10 –4 S·cm –1 ). The latter was elucidated via impedance spectroscopy and further studied by electronic structure calculations, revealing vacancy migration as the dominant Li + transport mechanism. Thus, studies on a selenido-LISICON family were found to be a very interesting starting point for an extension of the LISICON-related solid state lithium ion conductors (SSLIC).