Tetrahedral Tilting and Lithium‐Ion Transport in Halide Argyrodites Prepared by Rapid, Microwave‐Assisted Synthesis

Abstract This study demonstrates a rapid, dry, microwave‐assisted (MW) synthesis method that enables preparation of halide argyroditesLi 6 PS 5 X ${\rm Li}_6 {\rm PS}_5X$ ( X = $X =$   Cl − ${\rm Cl}^-$ ,Br − ${\rm Br}^-$ ,I − ${\rm I}^-$ ) in less than 20 min. The structures and ion transport properties of the resulting materials are compared with those synthesized by conventional solid‐state synthesis methods. The microwave‐assisted method leads to increased4 a / 4 d $4a/4d$ site disorder and elevated Arrhenius prefactors ( σ 0 $\sigma _0$ ), which lead to an order of magnitude improvement in the 30 ∘ C $^\circ{\rm C}$ ionic conductivity of MW‐Li 6 PS 5 I ${\rm Li}_6 {\rm PS}_5{\rm I}$ . X‐ray pair distribution function analysis (XPDF) reveals significant rotational disorder of thePS 4 3 − ${{\mathrm{PS}}_{4}}^{3-}$ units, which is impacted by the synthesis method, choice of halide, and presence ofS 2 − ${\rm S}^{2-}$ / X − $X^-$ site disorder. These rotational displacements are strongly correlated with ion transport, specificallyσ 0 $\sigma _0$ and entropy of migration ( Δ S m $\Delta S_m$ ). Overall, this study demonstrates a rapid synthesis route for preparing high‐quality halide argyrodite solid‐state electrolytes in less than 20 min, and further unravels atomistic insights into the interplay of structural disorder, rotational dynamics, and ion transport mechanisms.