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Insertion of Magnesium into Antimony Layers on Gold Electrodes:Kinetic Behaviour
ChemElectroChem ( IF 3.5 ) Pub Date : 2021-09-08 , DOI: 10.1002/celc.202100918
Da Xing 1 , Pawel Pawol Bawel 1 , A. A. Abd-El-Latif 2 , Lingxing Zan 3 , Helmut Baltruschat 4
Affiliation  

Magnesium based secondary batteries are regarded as a viable alternative to the immensely popular Li-ion systems. One of the largest challenges is the selection of a Mg anode material since the insertion/extraction processes are kinetically slow because of the large ionic radius and high charge density of Mg2+. In an attempt to bridge the gap between insertion measurements in 3D composite electrode materials and that in an idealized pure model system, we studied the insertion and diffusion of Mg in a thin, massive layer of Sb deposited on Au by using PITT, CV, and potential step experiments. Sb has been suggested as an insertion material because magnesium can form intermetallic compound with it. The layered crystal structure of Sb leads should facilitate formation of such an intermetallic phase. Mg insertion from a MACC/tetraglyme electrolyte into Sb starts 300 mV positive of the onset potential of Mg deposition as shown by cyclic voltammetry. The molar ratio of Mg to Sb agrees well with the stoichiometry of Mg3Sb2 alloy (Zintl-phase). The diffusion coefficient of Mg-insertion into Sb – layers and the charge transfer rate have been estimated by the above techniques. Such diffusion coefficients, albeit still somewhat “apparent”, are much more closely related to the true diffusion coefficient in the metal or alloy. The solid-state diffusion coefficient of Mg into the Sb layers is in the range of 4–8×10−14 cm2 s−1. A very high Tafel slope of 370 mV/dec was found in potential step experiments. Mg insertion was further investigated by XPS measurements. Besides Mg and Sb, Al and Cl signals were also detected, particularly at the outer parts of the layer.

中文翻译:

将镁插入金电极上的锑层:动力学行为

镁基二次电池被认为是非常流行的锂离子系统的可行替代品。最大的挑战之一是镁阳极材料的选择,因为 Mg 2+ 的离子半径大和电荷密度高,因此插入/提取过程在动力学上很慢. 为了弥合 3D 复合电极材料中的插入测量与理想化纯模型系统中的插入测量之间的差距,我们通过使用 PITT、CV 和潜在的步骤实验。Sb 已被建议作为插入材料,因为镁可以与它形成金属间化合物。Sb 引线的层状晶体结构应有助于形成这种金属间相。如循环伏安法所示,镁从 MACC/四甘醇二甲醚电解质插入 Sb 开始 300 mV 的镁沉积起始电位正值。Mg 与 Sb 的摩尔比与 Mg 3 Sb 2的化学计量一致合金(Zintl 相)。Mg 插入到 Sb 层的扩散系数和电荷转移率已通过上述技术估计。这种扩散系数虽然仍然有些“明显”,但与金属或合金中的真实扩散系数更密切相关。Mg进入Sb层的固态扩散系数在4-8×10 -14  cm 2  s -1的范围内。在电位阶跃实验中发现了 370 mV/dec 的非常高的 Tafel 斜率。通过 XPS 测量进一步研究了 Mg 插入。除了 Mg 和 Sb,还检测到 Al 和 Cl 信号,特别是在层的外部。
更新日期:2021-10-07
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