Cubic rocksalt Li₂SnS₃ and a solid solution with Li₃NbS₄ prepared by mechanochemical synthesis

Cubic Li₂SnS₃ with NaCl structure and the solid solution with Li3NbS4 were developed by mechanochemical synthesis. Cubic Li₂SnS₃ is a metastable phase, and the previously reported monoclinic Li₂SnS₃ is a stable phase. Cubic Li₂SnS₃ acts as an ionic conductor, and the solid solution of Li₃NbS₄-Li₂SnS₃ can be used as an electrode active material in lithium secondary batteries. Li_2.933Nb_0.8Sn_0.267S₄ and Li_2.857Nb_0.571Sn_0.571S₄ shows large reversible capacities of 318 and 286mAhg^-1, respectively. The capacity of these materials depends less on the niobium content than on the electrical conductivity. The reversible capacity in the 2-V region is mainly attributable to redox reactions involving rather sulfur than tin.