The rapid expansion of the lithium-ion batteries (LIBs) market not only raised the price of raw materials but also attracted increasing concern of the environmental hazards from the inappropriate disposal of spent LIBs. It is thus desirable to recycle the spent LIBs from both economic and environmental perspectives. This thesis aims at designing the recycle processes for different cathode materials (LiNi_xMn_yCo_1-x-yO₂, and LiNi_xCo_yAl_1-x-yO₂). Oxalic acid was chosen as the key component to recover lithium from LiNi_xMn_yCo_1-x-yO₂. Using LiNi_0.5Mn_0.3Co_0.2O₂ (NMC-532) as the base case cathode materials, 96.3% of lithium was dissolved along with 2.16% of manganese. An integrated process based on chemical and anti-solvent precipitation was synthesized to separate and recover manganese a...[ Read more ]

The rapid expansion of the lithium-ion batteries (LIBs) market not only raised the price of raw materials but also attracted increasing concern of the environmental hazards from the inappropriate disposal of spent LIBs. It is thus desirable to recycle the spent LIBs from both economic and environmental perspectives. This thesis aims at designing the recycle processes for different cathode materials (LiNi_xMn_yCo_1-x-yO₂, and LiNi_xCo_yAl_1-x-yO₂). Oxalic acid was chosen as the key component to recover lithium from LiNi_xMn_yCo_1-x-yO₂. Using LiNi_0.5Mn_0.3Co_0.2O₂ (NMC-532) as the base case cathode materials, 96.3% of lithium was dissolved along with 2.16% of manganese. An integrated process based on chemical and anti-solvent precipitation was synthesized to separate and recover manganese and lithium with high recovery and high purity from the liquid after dissolution. Ammonia dissolution was utilized to recover Ni, Co, and Mn from the solid residue of the mixed oxalates produced from selective lithium dissolution. When NH₃-(NH₄)₂C₂O₄ was used, 97.2% of nickel and 0.6% of cobalt were dissolved, and no manganese was detected in the solution. The overall recovery of Ni, Co, and Mn was 94.4%, 90.9%, and 99.4%, respectively. Another possibility to handle the mixed oxalates (Ni, Co, and Mn) was developed by converting them to mixed sulfates through an acid baking treatment. A process was developed to use the recycled mixed sulfates as the metal feed for LiNi_1/3Mn_1/3Co_1/3O₂ precursor synthesis. The influence of different factors, including pH, the concentration of NH₄OH, atmosphere, and reaction time, on the quality of the precursor was investigated. A casual table has been developed to guide the synthesis of high-quality LiNi_1/3Mn_1/3Co_1/3O₂ precursors. Thus, this thesis has developed a complete process to recycle the metals from spent LIBs back to cathode materials. In addition, the same approach was shown to work well for the recycle and recovery of all the metal from LiNi_0.8Co_0.15Al_0.05O₂ (NCA) cathode material that is commonly used in EVs.