Dataset for Development of Analytical Techniques for Lithium-Sulfur Batteries

Dataset supports: Liam Michael Furness (2020) Thesis. Development of Analytical Techniques for Lithium-Sulfur Batteries. University of Southampton. The aim of this study is to develop analytical techniques that can be used to better understand the lithium-sulfur (Li-S) battery system. The first technique involves the determination of the total atomic sulfur content and the average polysulfide chain length of a polysulfide solution. These experiments elucidated the 2-phase boundaries and eutonic point, giving an accurate representation of the ternary (lithium sulfide-sulfur-electrolyte) phase diagram. The 2-phase boundary describes the maximum solubility of a polysulfide solution in contact with either solid lithium sulfide or solid sulfur. On the other hand, the eutonic point describes the maximum solubility of a polysulfide solution in contact with both solid lithium sulfide and solid sulfur, thus the concentration of polysulfide species at the eutonic point is the maximum that can be achieved. The saturation concentration of polysulfide species will depend on the nature of the solvent and the lithium salt, and these variables can be tuned to improve the Li-S battery performance. This was observed when increasing the electrolyte salt concentration which limited the polysulfide solubility and in turn improved the cyclability of the Li-S battery. Therefore, the composition of the ternary phase diagram can be implemented to explain changes in Li-S battery galvanostatic cycling performance. The second technique, electrochemical impedance spectroscopy, will give further insight to the Li-S battery system. This technique, initially developed from Lasia et al. to determine the electroactive surface area of catalysts, has been applied to the cathode formulations for Li-S batteries in this study.1 Starting with the impedance of the basic components in a Li-S battery to understand features on the Nyquist plot. The complexity of cell setup was increased until the impedance of a full Li-S battery was achieved. This method allows determination of the specific surface area of different Li-S battery cathode formulations whilst also studying how the specific surface area of an electrode changes during galvanostatic cycling.