Influence of cold sintering process on the structure and properties of garnet-type solid electrolytes

• Published in: Ceramics international 2020-08, Vol.46 (11), p.18544-18550
• Main Authors: Wang, Xinchao, Wang, Jinzhu, Li, Fuzhen, Zhu, Feng, Ma, Cheng
• Format: Article
• Language: English
• Subjects: Cold sintering process; Garnet; Grain boundary; Ionic conductivity; Solid electrolyte
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2020.04.160

Li-stuffed garnet oxides are one of the most promising solid electrolytes for Li batteries, but their development is impeded by the overly high sintering temperature (above 1000 °C), which causes uncontrollable Li evaporation and poor repeatability of synthesis. The present study evaluates the possibility of addressing this issue using a recently developed technique called cold sintering process (CSP). We demonstrates that CSP can easily realize a high density of 87.7% at an extremely low temperature of 350 °C. However, the material becomes air sensitive after CSP, and the conductivity is degraded. Detailed structural and chemical analyses reveal that such detrimental effects arise from the inter-granular phase induced by the preferential dissolution of Al and Li. Therefore, in order to take full advantage of CSP during solid-electrolyte fabrication, the incongruent dissolution issue must be the focal point of improvement. Our results suggest that CSP is a promising solution to the overly high sintering temperature of garnet electrolytes, and deserves more attention in future studies.