Synergic effect of Bi, Sb and Te for the increased stability of bulk alloying anodes for sodium-ion batteries
Synergic effect of Bi, Sb and Te for the increased stability of bulk alloying anodes for sodium-ion batteries
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DOI：
10.1039/c7ta07648g
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发表时间：
2017-11-28
影响因子：
11.9
通讯作者：
Margadonna, Serena
中科院分区：
文献类型：
--
作者：
Orzech, Marcin W.;Mazzali, Francesco;Margadonna, Serena
与钠发生合金化反应的材料的有效使用受到循环过程中发生的大量体积变化的阻碍。提高循环稳定性的最常见方法之一是纳米结构化。然而，材料颗粒减小所需的工艺几乎不能转移到大规模生产中。为了解决这一问题，设计了三元合金Bi_（0.25）Sb_（1.75）Te_3，并对其电化学性能进行了研究。系统的选择是由Sb和Te显示的大可逆容量以及Bi非常理想的抗断裂性驱动的。实际上，微米尺寸的Bi 0.25 Sb 1.75 Te 3的本体粉末显示出高容量保持率（在200 mA g（-1）下100次循环后保持初始容量的91%）和优异的平均库仑效率（100次循环为99.9%），这两者都上级于对于本体和纳米尺寸形式的双组分对应物Sb 2 Te 3所观察到的那些。这种行为表明，用Bi少量取代Sb确实对电化学性能具有深远的影响。甚至更令人信服的是，当活性材料为微米级粉末形式时，观察到增强的性能和稳定性，而当在碳复合材料中为纳米级时，则没有。这种行为归因于颗粒尺寸对钠化反应途径以及对SEI钝化层的厚度和组成的影响。三元合金的稳定性的改善表明，多组分系统的仔细优化可以导致显着的性能增强，而不需要尺寸限制，开辟了一条道路，以方便和低成本的电极制造。
Effective use of materials that undergo alloying reactions with sodium is hampered by the substantial volume changes that occur during cycling. One of the most common approaches to improve cycling stability is nanostructuring. However, the processes required for material's particle downsizing are hardly transferable to large scale production. To alleviate such problems, the ternary alloy Bi0.25Sb1.75Te3 has been designed and its electrochemical performance investigated. The choice of system was driven by the large reversible capacities displayed by both Sb and Te coupled with the highly desirable fracture resistance of Bi. Indeed, micron-sized bulk powder of Bi0.25Sb1.75Te3 showed high capacity retention (retaining 91% of the initial capacity after 100 cycles at 200 mA g(-1)) and an excellent average coulombic efficiency (99.9% for 100 cycles), both of which are superior to those observed for the bi-component counterpart Sb2Te3 as bulk and nanosized forms. This behaviour indicates that a small substitution of Sb with Bi does have profound effects on the electrochemical performance. Even more compelling is the observation that enhanced performance and stability are observed when the active material is in the form of micron-sized powder and not when nanosized in a carbon composite. This behaviour is ascribed to the influence of particle size on the (de) sodiation reaction pathways and on the thickness and composition of the SEI passivation layer. The improved stability of the ternary alloy shows that careful optimization of multicomponent systems could lead to remarkable performance enhancement without the necessity of size confinement, opening the way to facile and low-cost electrode manufacturing.