兴奋剂
电化学
锰
氧化还原
离子
材料科学
八面体
氧化物
阴极
雅恩-泰勒效应
无机化学
化学工程
氧气
纳米技术
化学
电极
光电子学
冶金
物理化学
有机化学
工程类
作者
Xiaobai Song,Ruonan Liu,Junteng Jin,Xudong Zhao,Yao Wang,Qiuyu Shen,Ziqing Sun,Xuanhui Qu,Lifang Jiao,Yongchang Liu
标识
DOI:10.1016/j.ensm.2024.103377
摘要
Manganese-based layered oxides with anionic redox activity are considered as one of the most promising cathode candidates for sodium-ion batteries (SIBs) owing to their abundant resources and high theoretical specific capacities. However, the severe Jahn-Teller (J-T) effect of Mn3+ and irreversible lattice oxygen loss result in rapid structural degradation and electrochemical performance deterioration. Herein, the functioning mechanism of F-doping in regulating the local and electronic structures of Mn-based layered oxides is unraveled. The introduction of the more electronegative F ions on one hand breaks the electronic symmetry of the MnO6 octahedra and effectively alleviates the J-T distortion, on the other hand suppresses the Zn ions migration through the strong Zn-F bonds and stabilizes the oxygen redox chemistry and facilitates the Na+ diffusion. The above reaction mechanisms are systematically validated by in-situ/ex-situ analyses and theoretical computations. As a result, the optimum P2-Na0.75Zn0.28Mn0.72O1.93F0.07 cathode demonstrates significantly improved rate capability (178.6 mAh g−1 at 0.1 C with 64.4 mAh g−1 at 10 C) and enhanced cycling durability (83.1% capacity retention over 400 cycles at 3 C) compared to the un-doped P2-Na0.75Zn0.28Mn0.72O2 material. This study clarifies the F-doping mechanism in layered oxides and provides new perspectives for designing high-energy and high-stability cathodes for SIBs.
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