Synthesized K ₂ O·11Al ₂ O ₃ as sagger matrix for the preparation of Li‐ion battery cathode materials at high temperatures

Abstract Refractory materials such as mullite, andalusite, forsterite, and cordierite are generally used to prepare saggers for the calcination of Li‐ion battery Li(Ni _x Co _y Mn _z )O ₂ (LNCM) cathode material. However, these compounds are prone to be attacked by the LNCM materials, thereby leading to short life spans and contamination of the Li‐ion battery cathode materials. To improve the corrosion resistance of refractory sagger materials, the most clear cut‐way is enhancing the corrosion resistance of matrix using a new refractory component. Potassium aluminate (K ₂ O·11Al ₂ O ₃ , KA ₁₁ ) with an excellent corrosion resistance against alkaline oxide was synthesized via solid‐state method using potassium carbonate (K ₂ CO ₃ ) and industrial alumina powder (Al ₂ O ₃ ). Interactions between KA ₁₁ and LNCM cathode materials at 800°C–1100°C were characterized by refractory‐LNCM precursor laboratory‐scale tests to understand the corrosion behavior of KA ₁₁ . The microstructure and phase composition of synthesized KA ₁₁ and the calcined KA ₁₁ ‐LNCM mixture cylinders were analyzed with SEM and XRD. The observations reveal that KA ₁₁ shows a better corrosion resistance to LNCM materials compared with mullite, cordierite, and forsterite. The addition of synthesized KA ₁₁ also favors the thermal shock resistances of mullite‐based sagger materials.