Surface Spin‐State Manipulation via a Strong Electronegative Ligand Field Enables Direct Regeneration of Spent Lithium‐Ion Battery Cathodes

Abstract

ABSTRACT The rapid growth of lithium‐ion batteries has intensified the need for efficient recycling of spent LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM) cathodes. However, direct regeneration is hindered by the high‐spin state of Ni 2+ ( S = 1) in degraded surface structures, which impedes Li + intercalation and limits repair efficiency. Here, we introduce a strong electronegative ligand field to modulate the surface NiO 6 coordination environment, enabling precise regulation of Ni spin state and electronic structure. This strategy alters the occupancy of Ni e g orbitals, converting high‐spin Ni 2+ (t 2 g 6 e g 2 , S = 1) to low‐spin Ni 3+ (t 2 g 6 e g 1 , S = 1/2) while downshifting the Ni d ‐band center. The resulting electronic reconfiguration weakens Ni‐Li interactions, enabling efficient lithiation and regeneration of the degraded NCM black mass. The regenerated cathode, when assembled into pouch cells, exhibits Ah‐level capacity with electrochemical performance comparable to commercial counterparts. This work establishes a direct correlation between Li + transport kinetics and the Ni spin‐state regulation, offering a new chemical paradigm for the direct regeneration of degraded cathodes.