Development of High-Performance LLZO Separators for Solid-State Batteries: Balancing Li Loss, Stability, and Morphology in a Tape Casting Process

Abstract

Ceramic solid-state batteries (SSBs) are considered a viable alternative to lithium-ion batteries with liquid electrolytes, as they offer greater safety at the cell level. The Li7La3Zr2O12 garnet (LLZO) is a promising solid electrolyte for SSBs due to its stability with lithium metal anode and its good ionic conductivity of up to 2 mS cm-1. However, scalable and economically feasible techniques for producing LLZO-based batteries are required to make them competitive in the market.Tape casting is an industrially scalable process for producing customizable ceramic components. Successful implementation of this method requires a deep understanding of the transformation of the LLZO powder during the whole process chain, especially the effects of Li loss due to air and protic solvents interaction as well as Li evaporation during sintering.In this talk, a novel approach for fabricating thin LLZO ceramic separators by tape casting will be presented, in which lithium saltis used as a lithium mediator source in different process steps to optimize the separator properties. Using XRD, Raman spectroscopy, NMR spectroscopy, and SEM, we systematically investigate the effects of material composition and process conditions on the compositional and electrochemical performance of tape-cast LLZO separators in symmetric cells. This research provides important insights for optimizing the manufacturing process and enables the development of high-performance LLZO ceramic separators for all-solid-state batteries.