Y. Zhang, Z.F. Chen, X.Y. Shi, C.X. Meng, P. Das, S.H. Zheng, F. Pan,* Z.-S. Wu*

Advanced Energy Materials, 2023, 13.

DOI: 10.1002/aenm.202203045 [PDF]

Li-rich materials are among the most promising cathode materials for lithium-ion batteries thanks to their high specific capacity. However, they exhibit poor structural stability, resulting in low initial coulombic efficiency and limited cycle stability. Herein, a long-neglected Li-deficient state is realized for Co-freelithium-rich cathode through a facile calcination medium-induced surface-corrosion (CMISC) strategy for alleviating the aforementioned drawbacks. The as-constructed Li-deficient lithium-rich cathode of Li_1.2-σMn_0.6Ni_0.2O₂(d-LMNO) exhibits enhanced capacity of 272 mAh/g,improved initial efficiency of 84.5%, and cycle stability with 82.0% retention over 200cycles. Besides, multiple in-situ and ex-situ investigations confirm the appropriate lithium depletion regulated 3d-transition metal interlayered disorder, resulting in excellent structural reversibility ofd-LMNO. Also, theory simulation suggests the crystal structure with Li-defects has lower energy and Li-diffusion energy barrier when the coordination interlayer 3d-metal has more Ni closest to the diffused Li, meaning less interlayered disorder. And migration of Li close to the vacancy is dominated by a tetrahedral site hopping path in the presence of additional vacancies around the Li vacancy, which has a low migration energy barrier. Moreover, similar results achieved in Co-containing Li-rich cathodes further demonstrate the universality of this simple CMISC strategy, exhibiting great potential for performance improvement and applicability.