Towards Recycling of All-Solid-State Batteries with Argyrodite Sulfide Electrolytes: Insights into Electrolyte and Electrode Degradation in Dissolution-Based Separation Processes

All-solid-state Li-ion batteries (ASSBs) represent a promising leap forward in battery technology, rapidly advancing in development. Among the various solid electrolytes, argyrodite thiophosphates Li6PS5X (X = Cl, Br, I) stand out due to their high ionic conductivity, structural flexibility, and compatibility with a range of electrode materials, making them ideal candidates for efficient and scalable battery applications. However, despite significant performance advancements, the sustainability and recycling of ASSBs remain underexplored, posing a critical challenge for achieving efficient circular processes. This study investigates the dissolution-based separation and recovery of argyrodite thiophosphate electrolytes and transition metal oxide electrode materials as a potential recycling strategy for ASSBs. A focus is set on the impact of solvent treatments on the recrystallization behavior of these electrolytes. Furthermore, the interactions between dissolved argyrodite thiophosphates and various transition metal oxide electrode materials (LiCoO2, LiMn2O4, LiNi0.8Mn0.1Co0.1O2, LiFePO4 and Li4Ti5O12) is examined to assess their influence on the functional properties of both the electrolytes and electrode materials. Structural, compositional and morphological changes are analyzed using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Our findings provide insights into the complexities of recycling ASSBs, but also highlight the potential for developing efficient, sustainable recycling processes.