Regeneration of Single‐Crystal with Repaired of the (003) Crystal Plane from Degraded Polycrystalline Ternary Cathode

Abstract

ABSTRACT The direct regeneration of spent polycrystalline cathode materials into highly stable single‐crystal counterparts heralds a transformative shift in the recycling of spent lithium‐ion batteries (S‐LIBs). However, current direct recycling approaches, reliant on molten salt‐mediated single‐crystal transformation, remain constrained by operational complexity and a fragmented mechanistic understanding of defect repair on the (003) crystal plane. Herein, we unveil a streamlined one‐step regeneration strategy leveraging the LiNO 3 ‐LiOH·H 2 O‐Li 2 CO 3 system, enabling the conversion of polycrystalline S‐NCM523 to single‐crystal R‐NCM523 while simultaneously reconstructing (003) crystal plane. DFT and in situ analyses demonstrate that CO 3 2 − , NO 3 − , and OH − preferentially adsorb at the 3a sites within the lithium (Li) layer of the (003) plane. Their oxygen atoms hybridize with Li's 2s orbitals and TM's 3d orbitals, effectively suppressing rock‐salt phase formation via Li vacancy filling and Oxygen vacancy repair. A Two‐step sintering protocol drives particle single‐crystallization and active lithium replenishment. The resultant R‐NCM523 cathode significantly suppresses H2‐H3 phase transitions, delivering an initial half‐cell capacity of 165.80 mAh/g and retaining 81.0% of its discharge capacity after 1000 full‐cell cycles. This precursor‐free strategy achieves a molten salt recovery rate exceeding 90%, providing an industrially viable pathway for efficient, low‐energy S‐LIB regeneration.