Ionic Conductivity of Lithium Phosphides

We comprehensively study the ionic conductivity in lithium phosphides, promising materials for energy storage applications, by using a combination of first-principles computations and machine learning interatomic potentials. Using quasiharminic approximation, we calculated convex hulls Li-P system at various temperatures temperature-composition phase diagram was obtained, delineating stability regions each phase. The stable (Li3P, LiP, Li3P7, Li3P11, LiP7) metastable (Li4P3, Li5P4, LiP5) compounds studied as function temperature. In some found have high room (10−3–10−2 S cm−1). Structures with lowest are LiP7, which diffusion is negligible whole temperature range 300–500 K. Li3P, Li4P3, there 3D Li atoms, while Li5P4 2D mechanism prevails, LiP5 LiP7 1D observed. This may provide insights development ion metal battery applications.