Cathode Recycling of Spent Sodium Ion Batteries

Sodium-ion batteries (SIBs) have been commercialized in 2023 and are expected to capture a substantial market share in the future. However, the material systems in SIBs are very similar to those in lithium-ion batteries (LIBs), which necessitate consideration of recycling in terms of safety issues, environmental concerns, and economic values. In this study, we present the first evaluations of the disassembly of spent commercialized SIBs and the leaching and regeneration of their cathode material (NaNi_1/3Fe_1/3Mn_1/3O₂). We find that pretreatment of SIBs recycling offers advantages, particularly in separating the cathode and removing impurities from the material surface. The primary challenge in recycling is that failed cathode materials are difficult to dissolve in traditional inorganic acids, with an extraction rate of only 57.4% even when a reducing agent is added. Fortunately, there is a possibility for the failed NaNi_1/3Fe_1/3Mn_1/3O₂ regeneration. By replenishing sodium and repairing the structure through thermal treatment, the capacity can be restored to 109.4 mAh g⁻¹, with potential practical applications. Economic analysis indicates that the recycling of spent SIBs through cathode material regeneration results in a profit of $3.76 kg⁻¹ battery, even surpassing the $2.64 kg⁻¹ battery profit from LIB recycling. We hope that this research will provide a foundation for SIB recycling.