Tape Casting of LLZO Ceramic Separators: An Overview of Challenges, Optimization Strategies, and Paths to Industrial...

Tape casting is a cost-effective process for the scalable and continuous production of thin layers from ceramic powders. In recent years, interest in the use of tape casting for the production of solid-state battery components such as ceramic separators, ceramic cathodes, or complete cells has grown significantly. This upswing has been particularly pronounced for ceramic battery components based on the garnet-type Li₇La₃Zr₂O₁₂ (LLZO) solid electrolyte, as it exhibits the highest chemical stability toward Li metal anodes, while also possessing high overall ionic conductivity and being processable under ambient conditions. Since the separator has a decisive influence on the battery performance, strict control of the tape casting process at every stage, from slurry formulation and sintering to posttreatment and cell integration, is crucial for the reproducible manufacture of LLZO battery components with satisfactory performance. This perspective provides a systematic analysis of the challenges of the LLZO tape casting process and examines their impact on morphology, phase stability, and electrochemical performance, which often lead to nonreproducible results in various studies. In addition to presenting state-of-the-art solutions to these interrelated problems, we offer our perspective and propose innovative approaches to address concerns about scalability and reproducibility. By identifying critical gaps and opportunities for future research and development, this overview aims to facilitate understanding of the real challenges in the industrialization of LLZO separators and ultimately contributes to the realization of commercially viable all-solid-state batteries.