Li₆SiO₄Cl₂: A Hexagonal Argyrodite Based on Antiperovskite Layer Stacking

A hexagonal analogue, Li6SiO4Cl2, of the cubic lithium argyrodite family solid electrolytes is isolated by a computation–experiment approach. We show that structure equivalent to antiperovskite electrolyte through anion site and vacancy ordering within stacking two close-packed layers. Construction models assemble these layers with combination motifs, both well known in large perovskite structural variants, followed energy minimization identifies Li6SiO4Cl2 as stable candidate composition. Synthesis determination demonstrate material adopts predicted site-ordered low conductivity ?10–10 S cm–1 at room temperature above an order–disorder transition 469.3(1) K. This establishes dynamic Li disorder analogous increases Li-ion mobility observed via NMR AC impedance spectroscopy. The compositional flexibility alongside this newly established connection, which enables use wealth unexplored chemistry significant field electrolytes.