Towards Recycling of LLZO Solid Electrolyte Exemplarily Performed on LFP/LLZO/LTO Cells**

Abstract All‐solid‐state lithium ion batteries (ASS‐LIBs) are promising due to their safety and higher energy density as compared to that of conventional LIBs. Over the next few decades, tremendous amounts of spent ASS‐LIBs will reach the end of their cycle life and would require recycling in order to address the waste management issue along with reduced exploitation of rare elements. So far, only very limited studies have been conducted on recycling of ASS‐LIBS. Herein, we investigate the recycling of the Li 7 La 3 Zr 2 O 12 (LLZO) solid‐state electrolyte in a LiFePO 4 /LLZO/Li 4 Ti 5 O 12 system using a hydrometallurgical approach. Our results show that different concentration of the leaching solutions can significantly influence the final product of the recycling process. However, it was possible to recover relatively pure La 2 O 3 and ZrO 2 to re‐synthesize the cubic LLZO phase, whose high purity was confirmed by XRD measurements.