Tunable Porosity and Structural Properties of Carbon Aerogels: Adapting Packing Density and Morphology of Dry-Film Cathodes

The increasing demand for high-energy-density storage systems to support green energy technologies has highlighted the limitations of lithium-ion batteries and spurred interest in lithium-sulfur solid-state batteries (LS-SSBs), as they offer significant advantages, such as high theoretical energy densities and improved safety. Despite intense research in the recent years, there is a lack of understanding regarding a favorable carbon structure as a sulfur host in LS-SSBs. This study investigates the use of carbon aerogels (CAs) with adaptable porosity and mechanical properties as conductive matrices in LS-SSB cathodes. Two different CAs are examined: a brittle, mesoporous aerogel (p-CA) and a flexible, macro- and microporous aerogel (f-CA). High sulfur utilization (∼1500 mAh g<inf>S</inf>⁻¹) is achieved using p-CA, but it suffers from low Coulombic efficiency and reversibility. Conversely, f-CA exhibits lower sulfur utilization but improved cycling stability. The combination of both aerogels results in a higher packing density of the LS-SSB cathode. High sulfur utilization and enhanced long-term stability are realized for the mixed cathode. These results demonstrate the potential of CAs as a customizable, scalable host matrix for LS-SSBs, enabling improved cathode morphology and electrochemical performance through controlled tuning of their structural and mechanical properties.