Impact of the Carbon Matrix Composition on the S/C Cathode Porosity and Performance in Prototype Li-S Cells

The lithium-sulfur battery is a promising electrochemical storage solution, especially for aviation and aeronautical applications, due to its high-gravimetric energy density (specific energy) and the abundance of sulfur. In recent years, the number of reported prototype cells and their realized energy have increased. This underlines the progress of technology readiness of the lithium-sulfur system. However, the influence of the cathode porosity as well as the porosity of the carbon material on the performance of prototype cells is still not fully understood. Consequently, in this study, the porosity of solvent-free processed cathodes is investigated, with varying carbon matrix composition, via mercury intrusion porosimetry and synchrotron tomography. Moreover, the swelling behavior of the S/C dry-film cathodes is investigated and mitigated. These cathodes are then electrochemically evaluated at pouch cell level with ether-based electrolytes with varying E/S ratios. The combination of the gained findings in pouch cells enables specific energies of 425 Wh kg-1 and 558 Wh L-1 at cell level.