ANALYTICAL TECHNIQUES FOR Li-S BATTERIES

摘要

Lithium sulfur rechargeable batteries are foreseen to be used in electric vehicles in the near future. To enable their placement to the market we need to improve their reliability and cycling performance. This can be done by selective change of the chemical environment in the Li-S battery, including electrolyte (solvents and salts), different combinations of cathode composites and different additives. With an aim to understand differences between different chemical environments, suitable and reliable analytical techniques that can effectively monitor the changes of interest, should be developed. In this work we present two newly developed analytical techniques which are capable to detect quantitative and qualitative differences between different polysulfide species in the electrolyte. More specifically, both proposed techniques can detect the polysulfides that have diffused away from the cathode composite. With a modified 4-electrode Swagelok cell we can quantitatively determine the amount of such polysulfides, while an in-situ UV-Vis cell gives us information about the composition of these polysulfides. Combining these techniques with a classical galvanostatic cycling method could lead to a better understanding, consequently, a faster tuning of Li-S battery properties.