Quantum Mechanics Reactive Dynamics Study of Solid Li-Electrode/Li₆PS₅Cl-Electrolyte Interface

We have performed a theoretical study of the Li/Li 6 PS 5 Cl interface and showed the ability of the applied computational methods to properly describe the chemical processes that occur at the interface. After a 500 ps ab initio molecular dynamics simulation, we find that the Li/Li 6 PS 5 Cl interface decomposes with formation of multiple phases and that the main decomposition products are Li 2 S, Li 3 P, LiCl, and possibly LiP. These findings are in good agreement with reported experimental data. The observed quick decomposition is attributed to the weak bonding between P and S. On the basis of this and earlier obtained experimental results, we conclude that the chemical instability may be an intrinsic problem of P–S-based solid electrolytes when they are in contact with Li-metal. Our results validate the effectiveness of the available computational tools to reach a deeper insight into the evolution of interfacial structures and properties prior to experiment.