Investigation of Al2O3 Crucible Contamination induced by extra Li2CO3 during Li7La3Zr2O12 Solid Electrolyte Sintering process

Al2O3 crucible is commonly used during the sintering process of Li7La3Zr2O12 pellets, which always introduces unintentional Al-containing impurities to the final product. Rare investigations are focused on the mechanism of this crucible contamination up to now. Based on the study in this work, it is found that the extra Li2CO3 in the Li7La3Zr2O12 powder is a crucial factor in forming this kind of Al-containing impurities in the obtained pellets. The pyrolytic Li2O from Li2CO3 will react with Al2O3 at high temperature, forming liquid Li-Al-O eutectic and further promoting the dissolution of aluminum oxide crucible. Besides, the extra Li2CO3 can also affect the compactness and the distribution of Al element in the pellets, resulting in crystal structure transformation.