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Atomic insights into surface orientations and oxygen vacancies in the LiMn2O4 cathode for lithium storage
Journal of Alloys and Compounds ( IF 5.8 ) Pub Date : 2021-03-04 , DOI: 10.1016/j.jallcom.2021.159387
Wangqiong Xu , Yonghui Zheng , Lina Lin , Weibin Lei , Zhenguo Wang , Haili Song , Yan Cheng , Ruijuan Qi , Hui Peng , Hechun Lin , Zhenzhong Yang , Rong Huang

Surface anisotropy of spinel LiMn2O4 crystal is of significance for strengthening the lithium storage. In this work, we investigate the evolutions of surface orientations and oxygen vacancies in the LiMn2O4 cathode materials by the spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM) technique. Firstly, the {111} lattice planes appear in the formed LiMn2O4 octahedra, and then the {110} and {001} crystal planes are observed in the subsequent truncated octahedral at a higher temperature or a longer annealing time. The LiMn2O4 crystals with dominated {111} and {110} planes and an appropriate amount of oxygen vacancies exhibits a superior cycling performance and rate performance, suggesting a synergistic effect of surface orientation and concentration of oxygen vacancies achieves an enhanced electrochemical performance. The introduction of oxygen vacancies can accelerate the diffusion of lithium-ions along {110} plane and strengthen the rate performance of LiMn2O4, as elucidated by the combination of Cs-STEM observation, X-ray photoelectronic spectra analysis and property measurements.



中文翻译:

锂离子储存LiMn 2 O 4阴极中的表面取向和氧空位的原子见解

尖晶石型LiMn 2 O 4晶体的表面各向异性对于增强锂的储存具有重要意义。在这项工作中,我们通过球差校正扫描透射电子显微镜(Cs-STEM)技术研究了LiMn 2 O 4正极材料中表面取向和氧空位的演变。首先,{111}晶面出现在形成的LiMn 2 O 4八面体中,然后在更高温度或更长的退火时间下,在随后的截短的八面体中观察到{110}和{001}晶面。LiMn 2 O 4具有{111}和{110}面为主且适量的氧空位的晶体显示出优异的循环性能和速率性能,表明表面取向和氧空位浓度的协同效应实现了增强的电化学性能。结合Cs-STEM观察,X射线光电子能谱分析和性能测量可以看出,引入氧空位可以加速锂离子沿{110}面的扩散并增强LiMn 2 O 4的速率性能。

更新日期:2021-03-11
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