Study On Solvent Extraction Recovery of Nickel and Cobalt From Ternary Spent Lithium-Ion Batteries and Reduction of Solvent Loss

This study introduces a sustainable and environmentally friendly process for selective co-extraction of Ni 2+ and Co 2+ from leaching solution of spent ternary lithium-ion batteries (LIBs) with neodecanoic acid (V10). The extraction conditions were systematically optimized, and a process for reducing extractant dissolution loss in the raffinate was specifically designed, with both the extraction and extractant recovery steps integrated into a continuous mixer-settler operation. Experimental results showed that under optimal conditions, the extraction efficiency of Ni and Co consistently exceeded 99.9%, and the concentrations of Li and Mg in the strip solution remained below 1 mg/L. This process achieved both ultra-high extraction of Ni and Co and deep separation from Mg and Li. Furthermore, the chemical oxygen demand (COD) of the raffinate was reduced from around 10,000 mg/L to below 1,000 mg/L, demonstrating the effectiveness of this method in significantly decreasing COD. In addition, the extraction mechanism and the mechanism for reducing extractant dissolution loss were also verified. This work provides insights for developing a potentially practical process based on the V10 extraction system to improve selective co-extraction of Ni and Co from complex solutions while reducing extractant dissolution loss.