Resynthesis of cathode active material from heterogenous leachate composition produced by electric vehicle (EV) battery recycling stream

Abstract

Massive growth of electric vehicle (EV) sales in recent years triggers the huge demands of certain elements for lithium-ion battery (LIB) production. To sustain the supply of the elements and contribute to its circularity, LIB recycling is one of the justified routes. Although hydrometallurgy is considered as the most common process in battery recycling, improvements are still required to make the recycling process cleaner by reducing the steps and minimizing the chemical use. To achieve this goal, co-precipitation method is proposed to produce cathode active metals (CAM) of Li, Ni, Mn and Co from the leach solution. As battery chemistry is evolving fast, in near future, the dominant LiNi1/3Mn1/3Co1/3O2 (LNMC 111) type will be replaced by other types with different NMC ratios. Hence, in this study, co-precipitation was tested to recover Li, Ni, Mn and Co from various leachates with different metal compositions, simulating leachates from different battery chemistries. A hydrometallurgy flowsheet comprising four precipitation steps for metal recoveries from leach solutions was developed. In the first stage, aluminium was removed as Al(OH)3 by increasing the pH of the leachate to 5.5. Cu was removed in the next stage as sulfide by adding sodium sulfide to the supernatant obtained in the first stage. In the third stage, Ni, Mn and Co were co-precipitated as hydroxide precursor by increasing pH of supernatant to 11. The results showed that >95% of Ni, >83% Co, and >42% of Mn could be precipitated from the leaching liquor. Finally, Li is recovered from the supernatant as carbonate precipitate by adding sodium carbonate. Ni,Mn,Co(OH)2 precursor was finally mixed with Li2CO3 precipitated and calcined to resynthesize CAM showing the potential of this process to close the loop of recycling.