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 Bi_0.25Sb_1.75Te₃ 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 Bi_0.25Sb_1.75Te₃ 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.

中文翻译：

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Bi，Sb和Te的协同作用可提高钠离子电池整体合金阳极的稳定性

循环过程中发生的大量体积变化阻碍了与钠发生合金化反应的材料的有效使用。改善循环稳定性的最常见方法之一是纳米结构。但是，材料颗粒尺寸减小所需的过程很难转移到大规模生产中。为了减轻这种问题，已经设计了三元合金Bi _0.25 Sb _1.75 Te ₃并研究了其电化学性能。系统的选择是由Sb和Te均显示出大的可逆容量以及Bi的极高的抗断裂性驱动的。实际上，Bi _0.25 Sb _1.75 Te _3的微米级散装粉末表现出高的容量保持率（在200 mA g ^-1下100次循环后，保留初始容量的91％）和出色的平均库仑效率（100次循环为99.9％），两者均优于双组分同类产品Sb ₂ Te ₃散装和纳米形式。该行为表明，Sb被Bi少量取代确实对电化学性能产生了深远的影响。更令人信服的观察结果是，当活性材料为微米级粉末形式时，而不是在碳复合材料中为纳米级时，观察到增强的性能和稳定性。该行为归因于粒度对（去）磺化反应途径以及对SEI钝化层的厚度和组成的影响。三元合金稳定性的提高表明，仔细优化多组分系统可以在不限制尺寸的情况下显着提高性能，从而为方便而低成本的电极制造开辟了道路。