The Li + diffusivity in the crystalline, glassy, and interfacial regions was evaluated using velocity-velocity autocorrelation functions. The general trend in Li + diffusivity was D glass > D interface > D crystal . Notably, the Li + diffusivity in the crystalline region of the interfacial model differed significantly from that in the bulk β-Li 3 PS 4 . This difference was attributed to altered PS 4 3rotational dynamics in the crystalline region in the interfacial model. A clear correlation was demonstrated between the q 3 of PS