Computational study of ideal electrolyte/anode interfaces for Na3SbS4/Na

As part of an effort to develop energy storage technology based on Na-ion batteries, recent papers in the literature\footnote{Wang {\em{et al.}}, {\bf{Angew. Chem. Int. Ed. 55}}, 8551–8555 (2016), Zhang {\em{et al.}}, {\bf{Adv. Sci. 2016}}, 1600089 (2016)} demonstrate the electrochemical stability of the solid electrolyte Na$_3$SbS$_4$ interfaced with a metallic Na anode. The integrity of this electrolyte/anode interface, which is essential to the success of these battery components, is attributed to the formation of a stable solid-electrolyte interphase (SSEI). We report the results of a computational study of this system, using first-principles methods to model ideal interfaces of Na$_3$SbS$_4$ with Na metal. The ideal interfaces were constructed from (110), (100), and (001) surfaces of tetragonal crystals of Na$_3$SbS$_4$ and Na metal in various configurations. The results show several likely components of the SSEI including a few broken Sb$-$S bonds and Na$_2$S groups stabilized at the outer layer of the interface.