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Probing Dopant Redistribution, Phase Propagation, and Local Chemical Changes in the Synthesis of Layered Oxide Battery Cathodes
Advanced Energy Materials ( IF 27.8 ) Pub Date : 2020-11-20 , DOI: 10.1002/aenm.202002719
Zhijie Yang 1 , Linqin Mu 1 , Dong Hou 1 , Muhammad Mominur Rahman 1 , Zhengrui Xu 1 , Jue Liu 2 , Dennis Nordlund 3 , Cheng‐Jun Sun 4 , Xianghui Xiao 5 , Feng Lin 1
Affiliation  

Achieving the targeted control of layered oxide properties calls for more fundamental studies to mechanistically probe their evolution during their synthesis. Herein, dopant distribution, phase propagation, and local chemical changes as well as their interplay in multielement‐doped LiNiO2 materials are investigated using spectroscopic, imaging, and scattering techniques. It is shown that dopants undergo dynamic redistribution in the Ni(OH)2 host lattice at the early stage of calcination (below 300 °C). Such redistribution behavior exhibits strong dopant‐dependent characteristics, allowing for targeted surface and bulk doping control. The Ni oxidation process exhibits depth‐dependent characteristics and the most rapid Ni oxidation takes place between 300 and 700 °C. Using Ni oxidation state as the proxy for the phase transformation, the buildup of heterogenous phase propagation in the early stage of calcination is shown, especially along the radial direction of secondary particles. The radial heterogenous phase distribution gradually decreases upon completing the calcination. However, a high degree of mosaic‐like heterogeneity may still be present in the final product, departing from the perfect layered oxide. The present study offers fundamental insights into manipulating multiscale materials properties during calcination for obtaining stable, high‐energy layered oxide cathodes.

中文翻译:

在层状氧化物电池阴极合成中探测掺杂剂的重新分布,相传播和局部化学变化

要实现对分层氧化物性能的目标控制,就需要进行更基础的研究,以机械方式探索其在合成过程中的演变。在这里,使用光谱,成像和散射技术研究了掺杂多元素掺杂的LiNiO 2材料中的掺杂物分布,相传播和局部化学变化以及它们之间的相互作用。结果表明,掺杂剂在Ni(OH)2中经历了动态重新分布。煅烧初期(低于300°C)的主晶格。这种重新分布行为表现出强烈的掺杂依赖性,从而可以有针对性地控制表面和体掺杂。镍的氧化过程具有深度相关的特性,最快的镍氧化发生在300至700°C之间。以镍的氧化态作为相变的代表,表明了煅烧初期异相扩散的建立,特别是沿二次粒子的径向。煅烧完成后,径向异相分布逐渐减小。但是,最终产品中仍可能存在高度马赛克状的异质性,这与理想的分层氧化物不同。
更新日期:2021-01-07
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