New Method Developed for Analyzing Lithium-sulfur Batteries
Lithium-sulfur batteries are a promising addition to lithium-ion batteries due to their high energy density and potentially low cost. However, they suffer from capacity fade over multiple charge-discharge cycles. This is due to the dissolution and diffusion of intermediate lithium polysulfide species, which can lead to loss of active material and reduced capacity over time. To further develop lithium-sulfur batteries, it is therefore essential to precisely characterize these species and thus prevent their formation. A team from MEET Battery Research Center at the University of Münster has developed a method that can be used to specify and quantify polysulfide anions and molecular sulfur in lithium polysulfide solutions in organic solvents.
Innovative Method Combination Provides Precise Results
“We have coupled high-performance liquid chromatography and inductively coupled plasma mass spectrometry to tackle this problem for the first time,” says Aleksei Sadykov, PhD student at MEET Battery Research Center and the International Graduate School for Battery Chemistry, Characterization, Analysis, Recycling and Application (BACCARA). “With this method combination, we can precisely quantify the different types of sulfur.” The research team discovered that tetrasulfide is the most abundant species in all lithium polysulfide solutions examined.
Furthermore, the scientists identified a clear trend for increasing mass fractions of long-chain polysulfides and molecular sulfur in the solutions with a high sulfur content. They observed the same trend for the shortest polysulfide anions. “Our method provides important insights into the distribution of polysulfides,” explains Sadykov. “This allows us to shed light on the polysulfide shuttle effect and optimize electrolyte additives for this type of batteries”.
Lead author Aleksei Sadykov also presented the newly developed method at this year's Nordic Conference on Plasma Spectrochemistry in Norway, and was awarded with a poster prize.
Detailed Results Online Available
The entire study has been published by the authors Aleksei Sadykov, Dr Yannick P. Stenzel, Dr Simon Wiemers-Meyer and Dr Sascha Nowak, MEET Battery Research Center as well as Prof. Dr Martin Winter, MEET Battery Research Center and Helmholtz Institute Münster of Forschungszentrum Jülich, in the “Journal of Analytical Atomic Spectrometry”.