Revealing the Magnesium‐Storage Mechanism in Mesoporous Bismuth via Spectroscopy and Ab‐Initio Simulations,Angewandte Chemie International Edition

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Revealing the Magnesium‐Storage Mechanism in Mesoporous Bismuth via Spectroscopy and Ab‐Initio Simulations
Angewandte Chemie International Edition ( IF 16.1 ) Pub Date : 2020-08-13 , DOI: 10.1002/anie.202009528
Xin Xu ₁ , Dongliang Chao ₁ , Biao Chen ₂ , Pei Liang ₃ , Huan Li ₁ , Fangxi Xie ₁ , Kenneth Davey ₁ , Shi‐Zhang Qiao ₁

Affiliation

We present mesoporous bismuth nanosheets as a model to study the charge‐storage mechanism of Mg/Bi systems in magnesium‐ion batteries (MIBs). Using a systematic spectroscopy investigation of combined synchrotron‐based operando X‐ray diffraction, near‐edge X‐ray absorption fine structure and Raman, we demonstrate a reversible two‐step alloying reaction mechanism Bi↔MgBi↔Mg₃Bi₂. Ab‐initio simulation methods disclose the formation of a MgBi intermediate and confirm its high electronic conductivity. This intermediate serves as a buffer for the significant volume expansion (204 %) and acts to regulate Mg storage kinetics. The mesoporous bismuth nanosheets, as an ideal material for the investigation of the Mg charge‐storage mechanism, effectively alleviate volume expansion and enable significant electrochemical performance in a lithium‐free electrolyte. These findings will benefit mechanistic understandings and advance material designs for MIBs.

中文翻译：

通过光谱和从头算模拟揭示中孔铋中镁的储存机理

我们提出了介孔铋纳米片作为研究镁离子电池（MIBs）中Mg / Bi系统电荷存储机制的模型。使用组合的基于同步加速器的operando X射线衍射，近边X射线吸收精细结构和拉曼的系统光谱调查，我们展示了一个可逆两步合金化反应机理Bi↔MgBi↔Mg ₃的Bi ₂。从头开始的模拟方法揭示了MgBi中间体的形成并证实了其高电导率。该中间体用作显着的体积膨胀（204％）的缓冲剂，并起着调节Mg储存动力学的作用。介孔铋纳米片是研究Mg电荷存储机理的理想材料，可有效缓解体积膨胀并在无锂电解质中实现显着的电化学性能。这些发现将有助于机械理解，并为MIB改进材料设计。

更新日期：2020-08-13

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