Comparative framework of solvent-assisted delamination for direct regeneration of NMC cathodes

Direct regeneration of lithium-ion battery cathodes offers a pathway to retain the embedded value of complex materials yet remains limited by inefficient separation and poorly understood surface transformations. Here, we establish a comparative framework for solvent-assisted delamination of LiNi 0.4 Mn 0.4 Co 0.2 O 2 (NMC442) cathodes recovered from end-of-life pouch cells. Mechanical and solvent-assisted strategies based on N -methyl-2-pyrrolidone (NMP), ethylene glycol (EG), and ethylene carbonate/propylene carbonate (EC/PC) are systematically evaluated across process metrics, structural integrity, surface chemistry, and electrochemical response. All solvent-assisted routes preserve the layered R-3m bulk structure, while distinct surface chemistries are observed after delamination. EG promotes efficient delamination through thermally activated binder disruption, whereas EC/PC enables low-temperature separation with reduced solvent demand and minimal current collector degradation, yielding the most balanced process performance. Despite structural retention, electrochemical activity remains severely limited, demonstrating that delamination alone does not restore functionality. Solid-state re-lithiation restores lithium intercalation, showing that electrochemical activity can be substantially recovered following subsequent treatment. Overall, these results provide a systematic basis for assessing solvent-assisted delamination strategies with respect to separation efficiency, material preservation, and subsequent electrochemical response.