Corrosion Behavior of Cobalt Oxide and Lithium Carbonate on Mullite-Cordierite Saggar Used for Lithium Battery Cathode Material Sintering

Mullite-cordierite ceramic saggar is a necessary consumable material used in the synthesis process of LiCoO2 that is easily eroded during application. In our study, we systematically investigated the characteristics and surface corrosion behavior of waste saggar samples. We divided the cross sections of waste saggar into the attached layer, hardened layer, permeability layer, and matrix layer. Then, we examined the high-temperature solid-state reactions between saggar powder and lithium carbonate or cobalt oxide to identify erosion reactants correlating with an increase in the number of recycled saggars. The results of time-of-flight secondary ion mass spectrometric analysis (TOF-SIMS) prove that the maximum erosion penetration of lithium can reach 2 mm. However, our morphology and elemental distribution analysis results show that the erosion penetration of cobalt was only 200 mu m. When enough lithium carbonate reacted, lithium aluminate and lithium silicate were the main phases. Our X-ray computed tomography (X-ray CT) analysis results show that the change in phase volume before and after the reaction, including the generation of oxygen and carbon dioxide gas, led to the internal crack expansion of the material-saggar interface. Our results can contribute to improving saggar and upgrading waste saggar utilization technology.

Automated summary

A study was conducted on the characteristics and surface corrosion behavior of waste saggar samples used in the synthesis process of LiCoO2. The erosion reactants in recycled saggars were identified through high-temperature solid-state reactions. The results showed significant erosion penetration of lithium compared to cobalt, with generation of key phases and internal crack expansion at the material-saggar interface. These findings contribute to the improvement of saggar and the utilization technology of waste saggars.