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

We have performed a theoretical study of the Li/Li6PS5Cl 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/Li6PS5Cl interface decomposes with formation of multiple phases and that the main decomposition products are Li2S, Li3P, 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.