Lattice-Electron Synergistic Pinning Strategy for Intensified Regeneration of Spent Ternary Cathodes

The hydrometallurgical recycling of spent lithium-ion batteries (LIBs) confronts a fundamental scientific challenge in enhancing the structure while restoring the cathode chemistry, particularly in remedying the intrinsic Ni/Li antisite disorder and lattice distortions that dictate cycling stability. Herein, we propose a synergistic lattice-electron pinning strategy induced by localized microenvironmental reconfiguration to achieve dual-intensification of the regenerated structure and performance of retired LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523). The constructed localized strongly correlated Na-O-Ni ionic-covalent-bonding network enhances the strength of Ni-O bond, anchoring the lattice oxygen and ultimately effectively suppressing planar gliding in (003) facets. Simultaneously, the enlarged electronegativity difference between Na and O elevates the local electrostatic potential of Ni site, and the consequently increased Δt drives the spin pinning of Ni³⁺ from high-spin (t_2g ⁵e_g ²) to low-spin (t_2g ⁶e_g ¹), significantly suppressing the superexchange interaction along Ni-O-TM bonds. The optimized regenerated cathode delivers a remarkable capacity retention of 69.6% after 400 cycles at 0.5 C, surpassing commercial NCM523 (42.3%) and unoptimized regenerated cathode (40.3%) by 164% and 172%, respectively, and ranks among the top-performing regenerated NCM cathodes to date. This work highlights the significance of pinning effect in hydrometallurgical and establishes a sustainable-route for converting spent LIBs into high-quality regenerated cathodes.