Formation of Lithium Lanthanum Zirconium Oxide Nanofibers: Insight from In-Situ Synchrotron X-Ray Scattering Study

Lithium lanthanum zirconium oxide (Li₇La₃Zr₂O₁₂) with a cubic crystal structure is a promising candidate for a solid-state electrolyte due to its good ionic conductivity, thermal stability, and relatively large electrochemical window against Li metal anodes. The formation of the cubic phase usually requests elevated temperatures and a relatively long annealing time. However, we have observed cubic phase LLZO at significantly lower temperatures in nanofibers than their bulk counterparts. To understand the phase transformation and stability of the LLZO nanofibers, we performed in-situ simultaneous Small-Angle and Wide-Angle X-ray Scattering (SAXS/WAXS) for the LLZO precursor nanofibers during their annealing between RT and 800 °C. In this study, we investigate the structural evolution and microstructure changes of the nanofibers as a function of temperature. The electrochemical properties of the LLZO nanofibers were also evaluated.