(Invited) Advancing Scalable Processing of Thin Sulfide Solid-State Electrolytes for High-Energy ASSBs

Advancing Scalable Processing of Thin Sulfide Solid-State Electrolytes for High-Energy ASSBs Guang Yang, Chanho Kim, and Yuanshun Li Chemical Sciences Division, Oak Ridge National Laboratory, Tennessee, 37831, Oak Ridge, United States yangg@ornl.gov In pursuit of next-generation high-energy-density batteries, all-solid-state batteries (ASSBs) offer a promising platform and can achieve energy levels otherwise difficult to realize with traditional liquid electrolytes. A key objective is to minimize the thickness of the solid-state electrolyte (SSE), thereby increasing a cell’s practical energy density. However, fabricating thin, free-standing sulfide-based SSE films has proven challenging. Conventional approaches often rely on rigid, cold-pressed pellets of argyrodite sulfide electrolytes (e.g., Li6PS5Cl) at the lab scale, which are bulky and heavy, negating potential gains in energy density. Our work addresses this challenge by demonstrating a solution-based processing method to produce sheet-type, thin sulfide SSE films. Through careful solvent selection—guided by Hansen solubility parameters—and strategic binder formulation, we enable slurry casting of Li6PS5Cl particles into thin, flexible, free-standing films. These films incorporate minimal polymer binder, preserving high ionic conductivity while reducing both thickness and areal specific resistance compared to pelletized electrolytes. Although higher binder content can create voids and hinder ion transport, our optimized solvent-binder strategy maintains the particle’s crystal structure, ensures sufficient ionic conductivity, and improves interfacial stability with the lithium-metal anode. In the second part of this presentation, we show that by optimizing both wet and dry processing techniques, as well as SSB assembly, we can achieve an energy density of 400 Wh kg⁻¹ at the single-layer cell level—approaching the theoretical maximum for silicon-based ASSBs. Silicon anodes offer a theoretical capacity nearly an order of magnitude greater than graphite, but their adoption in ASSBs has been limited by challenges such as electrode engineering, cost, and reliance on impractical cold-pressed pellet cells. By integrating our thin sulfide electrolyte film with microsized, cost-effective silicon anodes, we have produced a stable, high-energy-density ASSB configuration that brings silicon-based ASSBs one more step closer to commercial viability. Acknowledgement This research was conducted at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) and is sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) in the Vehicle Technologies Office (VTO) through the Advanced Battery Materials Research (BMR) Program, managed by Drs. Simon Thompson and Tien Duong. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. We are grateful for the fruitful discussions with Dr. Jagjit Nanda at SLAC and Stanford University. References: Mills, A., Kalnaus, S., Tsai, W.Y., Su, Y.F., Williams, E., Zheng, X., Vaidyanathan, S., Hallinan Jr, D.T., Nanda, J. and Yang, G., 2024. Elucidating Polymer Binder Entanglement in Freestanding Sulfide Solid-State Electrolyte Membranes. ACS Energy Letters, 9, pp.2677-2684. Mills, A., Tsai, W.Y., Brahmbhatt, T., Self, E.C., Armstrong, B.L., Hallinan, D.T., Nanda, J. and Yang, G., 2023. Navigating the complexities of solvent and binder selection for solution processing of sulfide solid-state electrolytes. MRS Communications, 13(6), pp.1063-1070. Li, Yuanshun, Yukio Cho, Jiyu Cai, Chanho Kim, Xueli Zheng, Wenda Wu, Amanda L. Musgrove et al. "Effects of catholyte aging on high-nickel NMC cathodes in sulfide all-solid-state batteries." Materials Horizons (2024). Tan, D.H., Chen, Y.T., Yang, H., Bao, W., Sreenarayanan, B., Doux, J.M., Li, W., Lu, B., Ham, S.Y., Sayahpour, B. and Scharf, J., 2021. Carbon-free high-loading silicon anodes enabled by sulfide solid electrolytes. Science, 373(6562), pp.1494-1499.