Chemical modification effect on synthesizing Al-doped LLZO cubic garnet

Abstract

Chemical modification of metal alkoxides is crucial for controlling hydrolysis and polycondensation, as variations in electronegativity can cause uneven chelation and polymerization, leading to solution uniformity issues, molecular segregation, and undesired phases. This study highlights the importance of precise modulation to prevent phases like tetragonal LLZO or pyrochlore, preserving the desired cubic garnet structure of Al-doped Li₇La₃Zr₂O₁₂ (LLZAO) at lower temperatures. Synthesis of Al-substituted LLZAO fine powders via the metal alkoxide method aims for molecular-level homogeneity. Controlling rapid hydrolysis of both Zr and Al alkoxides is crucial for stabilizing monophasic cubic LLZAO and achieving lower calcination temperatures of 750 °C within 3 h, resulting in a sintered pellet with significant bulk ionic conductivity of 1.14 × 10⁻⁴ S cm⁻¹ at room temperature, underscoring the potential of chemically modified LLZAO as an efficient solid electrolyte for next-generation lithium-ion batteries.