Structure and Diffusion Pathways in Li6PS5Cl Argyrodite from Neutron Diffraction, Pair-Distribution Function Analysis, and NMR

The interest in all solid-state batteries has increased notably over the last years. Reasons are, among others, the demand for higher energy densities in storage devices and considerable safety issues in classical battery systems based on liquid electrolytes. One solution is the usage of solid electrolytes in battery systems. Because the crystal structure highly correlates with ion migration, the focus of our work is a detailed determination of the structure and Li pathways in the solid electrolyte argyrodite-type Li6PS5Cl. With neutron diffraction an additional Li site was experimentally detected. The comparison of maximum entropy method and differential bond valence analysis revealed the Li ion hopping pathways. With pair-distribution function analysis, a distortion of the [PS4](3-) tetrahedra resulting in a local monoclinic structure is found. A modulation of the local monoclinic structure is averaged out on longer length scales to an overall cubic structure that is known from the literature.