Realizing Low-Pressure Operation of All-Solid-State Lithium-Sulfur Batteries via Carbon-Coated Current Collectors

Stable operation of all-solid-state lithium-sulfur batteries (ASSLSBs) under reduced external pressures necessitates overcoming critical interfacial challenges and managing substantial electrode volume changes during cycling. This study introduces a carbon primer coating applied to aluminum (Al) current collectors as an effective strategy to enhance interfacial adhesion and reduce delamination at low pressures. The carbon coating provides uniform current distribution across the interface and improves contact conformality, addressing a critical issue for practical pouch cell applications. The interface design was evaluated by laminating dry-processed Li2S composite cathodes onto carbon-coated Al current collectors with varying surface areas. Interfacial resistance and the mechanical robustness of electrode-current collector interfaces under different pressures were systematically characterized using direct current polarization measurements. Advanced imaging methods, including focused ion beam scanning electron microscopy (FIB-SEM) and X-ray computed tomography (CT), were employed to examine interfacial integrity and detect any morphological changes throughout cycling. Furthermore, to manage significant volume variations inherent in ASSLSBs—particularly the 79% volumetric shrinkage of Li2S cathodes and 280% expansion of silicon (Si) anodes during cycling—the research integrates Si anodes with Li2S cathodes. This combination ensures volumetric compensation, significantly enhancing structural stability and cycling performance at reduced pressures. Overall, this interface engineering strategy and electrode design optimization demonstrate significant improvements in both energy density and cycling stability for ASSLSBs. This research provides a scalable solution, highlighting the potential for high-performance, low-pressure-operating pouch cell configurations.