Defect‐Mediated Heteroepitaxial Co‐Regeneration Strategy for Direct Regeneration of Spent Cathodes Materials

Abstract The efficient recycling of retired lithium‐ion battery materials is crucial for resource conservation and environmental sustainability. Direct regeneration significantly reduces waste and process complexity compared to pyrometallurgical and hydrometallurgical approaches. Herein, the study presents a defect‐mediated heteroepitaxial co‐regeneration strategy. The strategy precisely utilizes the inherent particle cracks and surface oxygen vacancy defects in spent lithium cobalt oxide to establish an ion diffusion pathway network, enabling quantitative replenishment of structurally deficient lithium. And the vacancy defects on the surface cooperatively guide La³⁺ and Ti⁴⁺ to form a concentration gradient doping distribution. Meanwhile, a continuous Li_0.3La_0.576TiO₃ perovskite coating with a thickness of ≈50 nm is constructed on the surface. Aberration‐corrected electron microscopy reveals the atomic‐scale occupation preferences of La³⁺/Ti⁴⁺ and the structural reconstruction morphology in directly regenerated materials. Combined with density functional theory calculations, the study further elucidates the defect‐mediated mechanism of reduced heterointerface formation energy and optimized Li⁺ migration barriers. The directly regenerated material delivers a high initial discharge capacity of 231 mAh g⁻¹ at 4.6 V and retains 89.1% capacity retention after 200 cycles. Moreover, this study provides crucial insights into recycling strategies for spent cathode materials and promotes the practical application of efficient recycling technologies.