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All-solid-state batteries (ASSB) using lithium-sulfur (Li-S) cathodes, present a low-cost energy storage solution that can achieve energy densities exceeding 500 Wh kg-1. However, their development in ASSBs has been hindered by poor kinetics, insulative interfaces, and (chemo)mechanical degradation, resulting in low utilization and cycle life. Here, we manipulate the meta-stability and redox activity of sulfide solid electrolytes to form ionically conductive interphases on the cathode surface using a simple and scalable synthesis approach. This creates a microstructure that enables high utilization and reversible electrochemical behavior with both sulfur and Li2S. Bulk and morphological characterization with X-ray absorption spectroscopy quantification is used to validate reversibility. Additionally, optimizing the cathode/catholyte microstructure by tailoring particle size to the micron-scale enhances rate performance for practical operation. The coupled (chemo)mechanical behavior of Li-S cathodes and sulfide solid electrolytes was found to alleviate internal stresses with cycling, especially when paired with high capacity anodes like silicon. As a result, this approach enables high loading sulfur cathodes up to 11 mAh cm-2 with stable operation at room temperature. Several high energy density cell architectures are demonstrated, particularly a Li2S anode-free pouch cell at 4.5 mAh cm-2 that can operate under low stack pressures. This work establishes new design strategies for Li-S cathodes, providing a pathway to enable high energy density batteries for a wide range of future applications.
Cronk et al. (Mon,) studied this question.