In recent years, increasing environmental awareness combined with political and economic incentives has driven the establishment of stricter regulations for battery recycling. Alongside the rapid progress in solid-state battery research, it has become essential to explore potential strategies for the recovery of valuable materials even prior to the large-scale commercialization of these technologies. With the implementation of lithium metal anodes, recent studies have increasingly focused on the selective recovery of lithium as a key aspect of sustainable recycling approaches.
Among the various solid electrolytes under investigation, the argyrodite-type ceramic Li₆PS₅Cl (LPSCl) stands out as one of the most promising candidates, exhibiting ionic conductivities comparable to those of conventional liquid electrolytes. However, sulfide-based materials present significant safety concerns due to their pronounced reactivity with moisture, leading to the formation of hydrogen sulfide (H₂S). This behavior must be carefully considered throughout all stages of material handling including recycling operations.
In this study, the formation of H₂S from composite cathodes containing sulfidic electrolyte as well as morphological changes on the surface were investigated under different atmospheric conditions, leading to important insights regarding the safe and proper handling of those materials. Additionally, the H₂S release from LPSCl after aqueous dissolution was determined. The results laid the foundation for an aqueous lithium recovery approach. The aqueous extraction of the electrolyte from the composite cathode was investigated together with a promising and environmentally compatible method to obtain lithium in the form of lithium phosphate with high purity and yields.