(633c) Scalable Fabrication of Multielement Ceramic Oxide Particles By an Aerosol Process

Aerosol processes have long been regarded as scalable methods to fabricate functional particles for the applications in energy storage and conversion. They have distinguished advantages to bridge the gap between the synthesizing at laboratory-scale and manufacturing at commodity-scale, for example, short residence time, facile instrument requirement, and simple operation. Aerosol processes have been successfully applied to produce particles with controllable particle-to-particle composition, morphology, and crystallinity. Unfortunately, those particles generally have a restricted number of elements. This is mainly attributed to the complex particle evolution, involving multiphase chemical reactions in less than seconds. When it comes to multielement powders, element segregation, phase impurity, and a large variety of morphologies can be expected in the product. Therefore, we developed an aerosol process, flame spray pyrolysis (FSP), to make multielement particles. To demonstrate the capability of our FSP process, garnet-type solid-state electrolyte, Li₇La₃Zr₂O₁₂ (LLZO), has been produced with a simple post-calcination step to achieve the cubic LLZO (c-LLZO) phase.

The conventional methods to synthesize c-LLZO rely on solid-state reactions starting from micron-sized oxides, repeated ball-milling, pellet-pressing, and calcination. Since the solid-state reactions are restricted by the long-diffusion distance and low material diffusivity, we utilized the FSP process. In FSP, the starting materials are mixed uniformly in precursor solutions to shorten the diffusion length. In the as-synthesized powders, Li, La, and Zr are distributed uniformly. The particles displayed only one crystal phase. Starting from those particles, c-LLZO powders were obtained through the calcination with a temperature below 700 ^oC.