Self-Reconstruction of Highly Degraded LiNi_0.8 Co_0.1 Mn_0.1 O₂ toward Stable Single-Crystalline Cathode

The ever-growing demand for resources sustainability has promoted the recycle of spent lithium-ion batteries to a strategic position. Direct recycle outperforms either hydrometallurgical or pyrometallurgical approaches due to the high added value and facile treatment processes. However, the traditional direct recycling technologies are only applicable for Ni-poor/middle cathodes. Herein, spent Ni-rich LiNi_0.8 Co_0.1 Mn_0.1 O₂ (S-NCM) to performance-enhanced single-crystalline cathode materials is directly recycled using a simple but effective LiOH-NaCl molten salt. The evolution process of the Li-supplement and grain-recrystallization during regeneration is systematically investigated, and the successful recovery of the highly degraded microstructure is comprehensively proven, including significant elimination of Ni²⁺ and O vacancies. Beneficial from the favorable reconstructed single-crystalline particles, the regenerated NCM (R-NCM) represents remarkably enhanced structural stability, electrochemical activity, O₂ and cracks suppression during charge/discharge, thus achieving the excellent performances in long-term cycling and high-rate tests. As a result, R-NCM maintains the 86.5% reversible capacity at 1 C after 200 cycles. Instructively, the present molten salt can be successfully applied for recycling spent NCMs with various Li and Ni compositions (e.g., LiNi_0.5 Co_0.2 Mn_0.3 O₂ ).