Surface Segregation‐Assisted Direct Regeneration of Spent Layer Cathodes

Abstract

ABSTRACT Direct regeneration has emerged as a promising approach, owing to its economic and environmental advantages. However, the efficiency of lithium replenishment and phase reconstruction—the core steps in the regeneration process—is critically hindered by the inert rock‐salt phase of spent cathode materials. Herein, we propose a segregation‐assisted regeneration strategy that leverages the segregation behavior of high‐valence elements to regulate reaction thermodynamics during the regeneration process, thereby preferentially inducing the in situ transformation of the NiO‐type rock‐salt phase. This transformation facilitates Li‐ion diffusion, accelerates the reconstruction of the layered structure, and enhances the overall structural stability. As proof of concept, tungsten (W 6+ ) is introduced into the regeneration process of spent LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cathodes, leading to the formation of Li‐W‐Ni‐O compounds and Li 2 WO 4 , which collectively facilitate the direct regeneration of the degraded material. The regenerated NCM523 delivers a high reversible capacity of 150 mAh g −1 at 0.5 C, outperforming commercial counterparts, and retains 83% of its capacity after 800 cycles in a 1.1 Ah pouch cell. Moreover, this strategy demonstrates broad applicability to other degraded layered cathode materials, including LiNi 0.6 Co 0.2 Mn 0.2 O 2 and LiNi 0.8 Co 0.1 Mn 0.1 O 2 . This work provides a scalable, energy‐efficient, and sustainable route for regenerating spent cathodes.