Atomic insights into the oxidative degradation mechanisms of sulfide solid electrolytes
Chuntian Cao, Matthew R. Carbone, Cem Komurcuoglu, Jagriti S. Shekhawat, Kerry Sun, Haoyue Guo, Sizhan Liu, Ke Chen, Seong‐Min Bak, Yonghua Du, Conan Weiland, Xiao Tong, Daniel A. Steingart, Shinjae Yoo, Nongnuch Artrith, Alexander Urban, Deyu Lu, Feng Wang
Abstract
Electrochemical degradation of solid electrolytes is a major roadblock in the development of solid-state batteries. Combining X-ray absorption spectroscopy characterization, first-principles simulations, and machine learning, here we report the atomic-scale oxidative degradation mechanisms of sulfide electrolytes using Li 3 PS 4 (LPS) as a model system. The degradation begins with a decrease of Li neighbor affinity to S atoms, followed by the formation of S-S bonds as the PS 4 tetrahedron deforms. After the first cycle, the PS 4 motifs become strongly distorted, and PS 3 motifs start to form. The distortion of PS 4 and the formation of S-S bonds are correlated with an increased interfacial impedance. We identify the spectral fingerprints of the local structural evolution and use them as a proxy for the electrochemical stability of phosphorus sulfide electrolytes, as demonstrated in argyrodite Li 6 PS 5 Cl. This study provides guidance for controlling macroscopic reactions through microstructural engineering and can advance the rational design of sulfide electrolytes.