插层(化学)
空位缺陷
材料科学
电化学
密度泛函理论
循环伏安法
介电谱
阳离子聚合
八面体
锂(药物)
尖晶石
过渡金属
无机化学
氧化物
离子
电极
化学
结晶学
物理化学
计算化学
催化作用
冶金
有机化学
高分子化学
内分泌学
医学
生物化学
作者
Shasha Guo,Toshinari Koketsu,Zhiwei Hu,Jing Zhou,Chang-Yang Kuo,Hong-Ji Lin,Chien-Te Chen,Peter Strasser,Lijun Sui,Yu Xie,Jiwei Ma
出处
期刊:Small
[Wiley]
日期:2022-09-04
卷期号:: 2203835-2203835
标识
DOI:10.1002/smll.202203835
摘要
Transition metal oxides (TMOs) as high-capacity electrodes have several drawbacks owing to their inherent poor electronic conductivity and structural instability during the multi-electron conversion reaction process. In this study, the authors use an intrinsic high-valent cation substitution approach to stabilize cation-deficient magnetite (Fe3 O4 ) and overcome the abovementioned issues. Herein, 5 at% of Mo4+ -ions are incorporated into the spinel structure to substitute octahedral Fe3+ -ions, featuring ≈1.7 at% cationic vacancies in the octahedral sites. This defective Fe2.93 ▫0.017 Mo0.053 O4 electrode shows significant improvements in the mitigation of capacity fade and the promotion of rate performance as compared to the pristine Fe3 O4 . Furthermore, physical-electrochemical analyses and theoretical calculations are performed to investigate the underlying mechanisms. In Fe2.93 ▫0.017 Mo0.053 O4 , the cationic vacancies provide active sites for storing Li+ and vacancy-mediated Li+ migration paths with lower energy barriers. The enlarged lattice and improved electronic conductivity induced by larger doped-Mo4+ yield this defective oxide capable of fast lithium intercalation. This is confirmed by a combined characterization including electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT) and density functional theory (DFT) calculation. This study provides a valuable strategy of vacancy-mediated reaction to intrinsically modulate the defective structure in TMOs for high-performance lithium-ion batteries.
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