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Roles of Coherent Interfaces on Electrochemical Performance of Sodium Layered Oxide Cathodes
Chemistry of Materials ( IF 7.2 ) Pub Date : 2018-06-22 00:00:00 , DOI: 10.1021/acs.chemmater.8b01556
Qun Huang 1 , Jiatu Liu 1, 2 , Sheng Xu 1 , Peng Wang 2 , Douglas G. Ivey 3 , Baiyun Huang 1 , Weifeng Wei 1
Affiliation  

Sodium layered cathode materials with higher specific capacity and enhanced cyclability are desired for advanced Na-ion batteries (NIBs). This work presents the controlled synthesis of a class of multiphasic P-/O-type Li-substituted NaxLi0.18Mn0.66Ni0.17Co0.17O2 layered composites. Complementary electron microscopy and X-ray-based spectroscopy analyses at multilength scales reveal that nanoscale intergrown nanostructures with various coherent-interface densities are featured in these layered composites. Improvements in electrochemical kinetics and cycling performance are observed in the triphasic P3/P2/O′3 composite with a larger amount of coherent-interface density. The interphasic strain induced by the lattice mismatch along the a/b plane between the Na–P3, Na–P2, and Li–O′3 phases may not only effectively suppress P3–P3″ and P2–P2″ phase transitions that account for enhanced cyclability but also facilitate smooth and fast Na diffusion between the prismatic sites leading to enhanced rate capability. Moreover, the gradual electrochemical activation process triggered by Li–O′3 phase in P2-containing composites is believed to play a positive role on the electrochemical kinetics of the composite materials.

中文翻译:

相干界面对钠层氧化物阴极电化学性能的作用

对于高级Na离子电池(NIB),需要具有更高比容量和增强的可循环性的钠层阴极材料。这项工作提出了一类多相P- / O型Li取代的Na x Li 0.18 Mn 0.66 Ni 0.17 Co 0.17 O 2的受控合成层状复合材料。互补电子显微镜和基于X射线的光谱在多长度尺度上的分析表明,这些层状复合材料具有各种相干界面密度的纳米级互生纳米结构。在具有大量相干界面密度的三相P3 / P2 / O'3复合材料中,观察到电化学动力学和循环性能的改善。晶格不匹配沿a / b引起的相间应变Na–P3,Na–P2和Li–O'3相之间的平面不仅可以有效抑制P3–P3”和P2–P2”相变,这增强了循环能力,而且还促进了棱柱形晶体之间Na的平滑快速扩散网站以提高费率功能。此外,据信由Li–O'3相触发的含P2复合材料的逐步电化学活化过程对复合材料的电化学动力学起着积极的作用。
更新日期:2018-06-22
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