The oxide-based garnet LLZO:Ga (Li6.4Ga0,2La3Zr2O12) is a promising solid-state battery electrolyte, offering high ionic conductivity, a wide electrochemical stability window, and lithium metal compatibility. However, upscaling of production requires to address challenges like reproducibility, cost reduction and energy efficiency. This work focuses on two scalable production techniques: Spray drying for synthesizing LLZO:Ga powders with controlled particle properties and tape casting for manufacturing LLZO:Ga free-standing foils. Investigations in this work confirm that phase-pure LLZO:Ga can be successfully produced while reducing the sintering temperature. Additionally, the use of pore-forming additives, enables the production of a porous LLZO:Ga tape acting as scaffold for both cathode material and polymer electrolyte. This paves the way for large-scale manufacturing of high-performance solid-state batteries.
In the first upscaling process, the objective of optimising the spray drying process was achieved by targeting a particle size distribution in the sub-micron range. The use of fine particles with high surface area enables lower sintering temperatures (below 1050°C), reducing energy consumption and minimizing Li-evaporation while maintaining the desired cubic LLZO phase.
For the second upscaling process (tape casting), slurry composition and rheology were optimized. Porous LLZO:Ga tapes were successfully fabricated, serving as mechanical supports for cathode materials and enhancing cell stability and ion transport. During the course of the project, porosities ranging from 50 to 70 vol% were successfully achieved. This allows for tailored loading with cathode materials, enabling optimization of battery performance and energy density. Electrochemical impedance spectroscopy (EIS) confirmed excellent performance, with dense pellets achieving a high ionic conductivity of 1.31 mS cm-1. Completely flat tapes with 13 mm width were successfully produced. The preliminary results show the strong potential in upscaling the electrolyte to 5×5 cm² tapes, marking a significant step toward large-scale production of advanced solid-state batteries with improved energy density and cycling stability.