Characterization of Li-S Batteries Using Laboratory Sulfur X-ray Emission Spectroscopy

Application of laboratory-based X-ray analytical techniques that are capable of a reliable characterization of the chemical state of sulfur within bulk battery cathode in parallel with electrochemical characterization is essential for further development of lithium-sulfur batteries. In this work, MeV proton-induced X-ray emission (XES) sulfur measurements were performed in ex situ mode on laboratory-synthesized sulfur standards and precycled battery cathodes. The average sulfur charge was determined from the energy shift of the K alpha emission line and from the spectral shape of the K beta emission spectrum. Finally, operando K alpha XES measurements were performed to monitor reduction of sulfur within battery cathode during discharge. The experimental approach presented here provides an important step toward more routine laboratory analysis of sulfur-based battery systems and also other sulfur-neighboring low-Z bulk materials with emission energies in the tender X-ray range.

Automated summary

The application of laboratory-based X-ray analytical techniques for reliable characterization of sulfur in battery cathodes is essential for the development of lithium-sulfur batteries. MeV proton-induced X-ray emission sulfur measurements were conducted ex situ on sulfur standards and battery cathodes, with the average sulfur charge determined from the energy shift of the K alpha emission line and spectral shape of the K beta emission spectrum. Operando K alpha XES measurements were performed to monitor sulfur reduction during discharge, representing an important step towards routine analysis of sulfur-based battery systems.