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−1and 558 Wh L−1at cell level. The impact of the carbon host matrix on the performance of solvent‐free‐processed S/C cathodes is investigated at pouch cell level. Furthermore, the morphology and porosity of the cathodes are investigated inter alia via synchrotron tomography. After the adaption of the carbon host matrix composition, energy densities at cell level of 425 Wh kg−1and 588 Wh L−1are achieved.