Origin of anomalous high-rate Na-ion electrochemistry in layered bismuth telluride anodes
Origin of anomalous high-rate Na-ion electrochemistry in layered bismuth telluride anodes
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DOI：
10.1016/j.matt.2021.01.005
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发表时间：
2021-04-07
期刊：
影响因子：
18.9
通讯作者：
He, Kai
中科院分区：
文献类型：
--
作者：
Cui, Jiang;Zheng, Hongkui;He, Kai
货车德瓦尔斯层状金属硫属化物Bi 2 Te 3在碱离子电池中显示出优异的容量和倍率性能，但与Li+、Na+和K+的潜在反应机理仍未被发现。出乎意料的是，Na+电化学在高电流密度下优于Li+和K+。在这里，原位透射电子显微镜被用来揭示锂化，钠化和钾化过程中的纳米级转变，这遵循两步转化和与Li+和Na+的合金化反应，以及三步嵌入-转化-与K的合金化反应。与直觉相反，钠化反应具有最高的反应动力学，其起源可以通过第一性原理和有限元模拟两个方面来阐明。Bi 2 Te 3和其Na-转化产物之间较低的界面应变调节能允许比Li-和K-离子反应更容易的钠化相变。在凹形钠化反应前沿的更高的电化学-机械应力集中促进了Na离子的持续扩散和反应传播这些基本见解对于快速充电碱离子电池至关重要。
van der Waals layered metal chalcogenide Bi2Te3 has shown exceptional capacity and rate capability in alkali-ion batteries but the underlying reaction mechanism with Li+ , Na+ , and K+ remains undiscovered. It is unexpected that Na+ electrochemistry outperforms Li+ and K+ at high current densities. Here, in situ transmission electron microscopy is used to uncover nanoscale transformations during lithiation, sodiation, and potassiation, which follows two-step conversion and alloying reactions with Li+ and Na+, and three-step intercalation-conversion-alloying reactions with K. Counterintuitively, sodiation exhibits the highest reaction kinetics, and its origin can be elucidated by first-principles and finite-element simulations in two aspects. The lower interfacial strain accommodation energy between Bi2Te3 and its Na-conversion products allows more facile sodiation phase transformation than Li- and K-ion reactions. The higher electrochemo-mechanical stress concentration at the concave-shaped sodiation reaction front facilitates continued Na-ion diffusion and reaction propagation These fundamental insights are essential for fast-charging alkali-ion batteries.