Ultrafast Li Electrolytes Based on Abundant Elements:   Li$_{10}$SnP$_2$S$_{12}$ and Li$_{11}$Si$_2$PS$_{12}$
  We report on the synthesis and characterization of two solid electrolytes, Li$_{10}$SnP$_2$S$_{12}$ and Li$_{11}$Si$_2$PS$_{12}$, which are based exclusively on abundant elements. Both compounds feature extremely high Li ion diffusivities, with the Si-based material even surpassing the present record holder, the related electrolyte Li$_{10}$GeP$_2$S$_{12}$. The structure and dynamics were studied with multiple complementary techniques and the macroscopic diffusion could be traced back to fast Li ion hopping in the crystalline lattice. 
Alexander Kuhn, Oliver Gerbig, Changbao Zhu, Frank Falkenberga,   Joachim Maier, and Bettina V. Lotsch
cond-mat.mtrl-sci