Optimal Sulfur Cathode for High-Energy Density All-Solid-State Li-S Batteries

All-solid-state lithium-sulfur batteries (ASSLSBs) offer substantial potential as a high-energy density and cost-effective energy storage technology. To achieve practically high specific energy in ASSLSBs (e.g., >400 Wh Kg^-1), sulfur cathodes with high areal capacity (>6 mAh cm^-2) are essentially needed to offset the relatively low working voltage of elemental sulfur cathode (1.9 V vs. Li). This requires high mass loading sulfur cathodes by maximizing both sulfur content in the whole electrode and sulfur utilization rate to reduce the parasitic weights, which still remains a challenge. We attemped to establish criteria for sulfur cathode selection by systematically investigating material impacts at both particle and electrode levels. Our findings indicate that unlike traditional liquid systems, solid sulfur cathodes necessitate the formation of high-density sulfur/solid electrolyte/carbon triple-phase boundaries and low-tortuous ionic/electronic paths. Detailed materials selection criteria will be discussed. Employing these principles, we engineered solid sulfur cathodes with 6-15 mAh cm^-2 and 50 wt% sulfur content and demonstrated high rate capability and long-term cycling stability against metallic Li anode. Details of the study will be presented and discussed at the meeting.