Sustainable Pathways for the Direct Recycling of Lithium-Ion Batteries

As the popularity of electric vehicles continues to rise so does the demand for lithium-ion batteries (LIB). A common cathode material for LIBs used in electric vehicles is lithium nickel manganese cobalt oxides (Li-Ni_xCo_yMn_1−x−yO₂, NMC). This is due to its high specific capacity (160 – 200 mAh/g) and voltage (~3.6 V). Currently, there are two types of battery recycling methods that are in use in at an industry level scale: hydrometallurgy and pyrometallurgy. The overall goal of these processes is to recover the raw materials as individual elements. These processes are energy intensive, generate other hazardous wastes, and are not economically advantageous. There is another recycling process known as direct recycling that offers a better solution for the recycling of lithium-ion batteries. The overall goal of direct recycling is the recovery, regeneration, and reuse of battery cathode material without breaking down the chemical structure. This approach is less energy consuming and generates less additional waste than then traditional hydrometallurgy and pyrometallurgy methods. This research has developed two different methods of direct recycling, Flux-Assisted Direct Regeneration and MechanochemAssisted Direct Regeneration. The Flux-Assisted Direct Regeneration method uses a eutectic lithium salt mixture and reduced annealing time and temperature to drastically improve the energy efficiency. This method was able to fully regenerate the NMC cathode material. The regenerated material had a better battery performance than the new commercial NMC material. The Mechanochem-Assisted Direct Regeneration method uses a planetary ball mill to achieve NMC cathode material regeneration. This method is more energy efficient while still achieving full relithiation and crystal structure recovery.