Direct Nickel Recovery From Spent NCM Lithium ‐ Ion Batteries Enabled by Hydrophobic Sulfur ‐ Donor Extractants

ABSTRACT

The increasing demand for lithium‐ion batteries (LIBs) attracts sustainable recycling, particularly for high‐value metals such as Ni and Co used in high‐Ni ternary cathodes. However, current hydrometallurgical processes rely on multistage solvent extractions that exhibit poor Ni selectivity and generate large quantities of Na ₂ SO ₄ waste because of extensive pH adjustment and extractant saponification. Herein, we report an organocatalyst‐inspired, sulfur‐donor extractants (TPA‐H) designed through molecular‐level engineering for highly selective direct Ni recovery. These P(V)‐based extractants enable direct and efficient Ni extraction under strongly acidic conditions (pH ∼0.5), achieving an exceptional Ni/Co separation factor (β) exceeding 2300. Mechanistic studies revealed that the optimized structure and coordination of the phosphorodithioate framework preferentially stabilize Ni(II) over competing metals. Large‐scale extractions using real spent LIB black mass leachates demonstrated >95% Ni extraction efficiency under acidic conditions. Subsequent stripping and recrystallization without an intermediate scrubbing step afforded high‐purity NiSO ₄ ·6H ₂ O (99.7%), while suppressing Na ₂ SO ₄ byproduct generation. The TPA‐Hs exhibited excellent recyclability over 10 consecutive cycles, and the recovered Ni was directly crystallized as high‐purity NiSO ₄ ·6H ₂ O. Furthermore, integration of an advanced‐flow reactor (AFR)–Zaiput separator platform enabled biphasic mass transfer, thereby overcoming the limitations of mixer–settler systems and facilitating automated continuous extraction–separation processes.