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

Matjaž Kavčič,Marko Petric,Robert Dominko,Sara Drvarič Talian,Alen Vizintin,Ava Rajh,Kristina Isaković

doi:10.1021/acsaem.0c02878

Abstract

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 Kα emission line and from the spectral shape of the Kβ emission spectrum. Finally, operando Kα 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.

Highlights

X-ray emission spectroscopy (XES) is emerging as a technique complementary to X-ray absorption spectroscopy (XAS), providing information on local electronic structure and bonding configuration of atoms within different bulk materials
We have extended the range of XES studies to tender X-ray range: we have used XES to study the electronic structure of sulfur in solid[9−11] and liquid materials.[12]
The main objective of this work is to explore the capabilities of sulfur XES as a laboratory analytical tool used to characterize electrochemical processes within lithium−sulfur (Li−S) batteries

Summary

Introduction

X-ray emission spectroscopy (XES) is emerging as a technique complementary to X-ray absorption spectroscopy (XAS), providing information on local electronic structure and bonding configuration of atoms within different bulk materials. XES in the hard X-ray range has been extensively used to study 3d transition-metal complexes.[2,3,6−8] The emission energy range of sulfur, remains out of reach for large in-air hard X-ray emission spectrometers used in these studies. We have extended the range of XES studies to tender X-ray range: we have used XES to study the electronic structure of sulfur in solid[9−11] and liquid materials.[12] The high scientific relevance of the tender X-ray range has been widely recognized, and several in-vacuum tender XES spectrometers have been developed recently.[13−17]

Objectives

Results

Conclusion