Closed-loop Recycling of Sulfide Solid Electrolytes from Spent Solid-State Sodium Batteries

All-solid-state sodium batteries (ASSSBs) are promising for large-scale energy storage due to sodium abundance and intrinsic safety. However, from a sustainability perspective, the recyclability of solid electrolytes is critical but largely unexplored, as many mature solid electrolytes rely on low-abundance, high-cost elements, limiting long-term scalability. Herein, we firstly report a closed-loop recycling strategy for Na₃SbS₄ (NAS) solid electrolytes guided by the DFT calculations, enabling efficient recovery and regeneration from spent all-solid-state sodium batteries via a mild dissolution-recrystallization-thermal treatment process. The recycled NAS (R-NAS) fully preserves the long-range crystal structure, local coordination environment, and chemical states of the pristine material. The R-NAS delivers good ionic conductivity, electrochemical stability, reduced polarization, enhanced rate performance, and superior cycling stability comparable to pristine NAS (P-NAS). This work demonstrates the feasibility and importance of the recycling of high-performance sulfide solid electrolytes from spent devices without compromising structural integrity or functionality. The proposed recycling strategy offers a generalizable and sustainable pathway for the reutilization of advanced solid electrolytes, contributing to the circular economy of all-solid-state battery technologies.