A novelty strategy induced pinning effect and defect structure in Ni-rich layered cathodes towards boosting its electrochemical performance

Layered Ni-rich transition metal oxide is treated as the most promising alternative cathode due to their high-capacity and flexible composition. However, the severe lattice strain and slow Li-ion migration kinetics severely restrict their practical application. Herein, a novelty strategy induced pinning effect and defect structure in layered Ni-rich transition metal oxide cathodes is proposed via a facile cation(iron ion)/anion (polyanion) co-doping method. Subsequently, the effects of pinning effect and defect structure on element valence state, crystal structure, morphology, lattice strain, and electrochemical performance during lithiation/delithiation are systematically explored. The detailed characterizations (soft X-ray absorption spectroscopy (sXAS), in-situ X-ray diffraction (XRD), etc.) and density functional theory (DFT) calculation demonstrate that the pinning effects built-in LiNi(0.9)Co(0.05)Mn(0.0)5O(2) materials by the dual-site occupation of iron ions on lithium and transition metal sites effectively alleviate the abrupt lattice strain caused by an unfavorable phase transition and the subsequent induction of defect structures in the Li layer can greatly reduce the lithium-ion diffusion barrier. Therefore, the modified LiNi0.9Co0.05Mn0.05O2 exhibits a high-capacity of 206.5 mAh g(-1) and remarkably enhanced capacity retention of 93.9% after 100 cycles, far superior to similar to 14.1% of the pristine cathodes. Besides, an excellent discharge capacity of 180.1 mAh g(-1) at 10 degrees C rate is maintained, illustrating its remarkable rate capability. This work reports a pinning effect and defect engineering method to suppress the lattice strain and alleviate lithium-ion kinetic barriers in the Ni-rich layered cathodes, providing a roadmap for understanding the fundamental mechanism of an intrinsic activity modulation and structural design of layered cathode materials. (C) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.