Cross-sectional X-ray nanodiffraction of LLZTO and glass-modified composites: lithium redistribution and dendrite mitigation

Lithium garnet-type electrolytes such as Li6.6La3Zr1.6Ta0.4O12 (LLZTO) are among the most promising oxide-based solid electrolytes due to their high ionic conductivity (~10⁻³ S/cm) and chemical stability. However, their polycrystalline nature facilitates lithium dendrite penetration along grain boundaries, which critically limits their practical application in solid-state batteries. We recently developed a strategy to modify LLZTO grain boundaries with lithium borate (LBO) and fluorinated borate glasses (LBO–AlF3). These electronically insulating, mechanically rigid glassy additives suppress dendrite growth and lower interfacial resistance against lithium metal. This proposal aims to use cross-sectional X-ray nanodiffraction at ID13 to quantify operando lithium-induced stress distributions, phase evolution, and microstructural changes in LLZTO and glass-modified composites. This experiment will, for the first time, reveal how glass additives alter the dendrite process.