Abstract This work developed a novel strategy for enhancing selective extraction of transition‐metal ions (Ni 2+ , Co 2+ , and Mn 2+ ) from spent lithium‐ion batteries by the so‐called “hydrogen bond (HB) network to manipulate coordination environment” in the deep eutectic solvent (DES) composed of octanoic acid (OctA), procaine (Pro), N,N‐di (1‐methylheptyl) acetamide (N503) (OctAProN503). The DES demonstrated the ultra‐high extraction efficiency (99.8%) of transition‐metal ions and separation selectivities for β Co 2+ /Li + , β Ni 2+ /Li + , and β Mn 2+ /Li + of 24,122, 64,782, and 35,439, respectively, outperforming other DESs reported from literature to date. The molecular‐level mechanism on enhancing extraction of transition‐metal ions was revealed by spectral analyses, quantum chemical (QC) calculations, and molecular dynamics (MD) simulations, namely (i) enhancing the coordination probability between transition‐metal ions and DES through densifying HB networks and (ii) increasing coordination intensity by modulating HB interactions within DESs. This work provides theoretical guidance for rational design of efficient DESs for recycling valuable metals from spent LIBs.
Wu et al. (Sun,) studied this question.