Synthesis and lithium conductivities of Li2SiS3 and Li4SiS4

The compositions in the LiSiS system were synthesized by using pyrolitic graphite-coated silica ampoules. Two ternary compounds, Li2SiS3 and Li4SiS4, were identified and their powder x-ray diffraction data were reported for the first time. Li2SiS3 had a = 6.735 Å, b = 11.664 Å, and c = 5.926 Å, with a space group Cmc21, while Li4SiS4 had a = 13.735 Å, b = 7.769 Å, and c = 6.147 Å, with a space group Pnma. The lithium conductivities of Li2SiS3 and Li4SiS4 at room temperature were 2 ×10−6 and 5 ×10−8 (Ω.cm)−1, respectively. Their ionic conduction behaviors were discussed based on their crystal structures deduced here.