Yttria as a secondary phase in LAGP for Solid State Battery Applications

Solid state batteries represent significant improvements in energy density, operating temperature, and safety over liquid batteries, but low ionic conductivity limits their commercial applicability. Ionic conductivity results from the interplay of several factors, including grain boundary interfaces, grain size, porosity, and crystal structure. Secondary phases may also play an important role. For example, yttria helps stabilize the crystal structure of ceramics such as zirconia at high temperatures, and it has also been demonstrated to improve ionic transport in solid-state electrolytes such as LAGP when introduced via glass melt synthesis. To explore the role of yttria in LAGP via more energy-efficient methods, we introduce yttria extrinsically to powder LAGP. Ball milling and hand mixing were used to disperse the yttria, and the material was consolidated by thermal sintering as well as microwave processing. Samples are analyzed with respect to the effect of yttria on grain growth, ionic conductivity, and microwave absorbance, and the results are discussed with respect to the underlying physical properties.