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首页> 外文期刊>ACS Omega >Probing the Critical Role of Sn Content in SnSb@C Nanofiber Anode on Li Storage Mechanism and Battery Performance
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Probing the Critical Role of Sn Content in SnSb@C Nanofiber Anode on Li Storage Mechanism and Battery Performance

机译：探讨SnSb @ C纳米纤维阳极中Sn含量对锂存储机理和电池性能的关键作用

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The minimization of the detrimental effects as a result of the drastic volume changes (few hundred times) occurring during repeated alloying–dealloying of lithium with group IV elements, e.g., tin (Sn), is a major challenge. An important design strategy is to have Sn as a component in a binary compound. SnSb is an important example where the antimony (Sb) itself is redox active at a potential higher than that of Sn. The ability of Sb to alloy with Li reduces the Li uptake amount of Sn in SnSb compared to that in bare Sn. Thus, the volume changes of Sn in SnSb will expectedly be much lower compared to that in bare Sn, leading to greater mechanical stability and cyclability. As revealed recently, the complete reformation of SnSb (for a molar ratio of Sn/Sb = 1:1) during charging is not achieved due to the loss of some fraction of Sn. Thus, the molar concentration of Sn and Sb in SnSb is also absolutely important for the optimization of battery performance. We discuss here SnSb with varying compositions of Sn encapsulated inside an electrospun carbon nanofiber (abbreviated as CF). The carbon-nanofiber matrix not only provides electron transport pathways for the redox process but also provides ample space to accommodate the drastic volume changes occurring during successive charge and discharge cycles. The systematic changes in the chemical composition of SnSb minimize the instabilities in SnSb structure as well as replenish any loss in Sn during repeated cycling. The composition plays a very crucial role, as magnitude of specific capacities and cyclability of SnSb are observed to depend on the variable percentage of Sn. SnSb-75-25-CF, which contains excess Sn, exhibits the highest specific capacity of 550 mAh g~(–1) after 100 cycles in comparison with pure SnSb (1:1) anode material at a current density of 0.2 A g~(–1) and shows excellent rate capability over widely varying current densities (0.2–5 A g~(–1)).
机译：将锂与锡（Sn）等IV族元素进行合金化和重复合金化过程中发生的剧烈体积变化（几百次），从而使有害影响最小化是一个重大挑战。一个重要的设计策略是将Sn作为二元化合物的成分。 SnSb是一个重要的例子，其中锑（Sb）本身具有氧化还原活性，且电势高于Sn。与裸露的锡相比，Sb与Li形成合金的能力降低了SnSb中Sn的Li吸收量。因此，与裸锡相比，SnSb中Sn的体积变化预计将低得多，从而导致更高的机械稳定性和可循环性。如最近所揭示的，由于损失了一部分Sn，所以在充电期间没有实现SnSb的完全重整（对于Sn / Sb的摩尔比为1：1）。因此，SnSb中Sn和Sb的摩尔浓度对于优化电池性能也绝对重要。我们在这里讨论的SnSb具有包裹在电纺纳米碳纤维（缩写为CF）中的Sn的不同组成。碳纳米纤维基质不仅为氧化还原过程提供了电子传输途径，而且提供了足够的空间来容纳在连续的充电和放电循环中发生的急剧的体积变化。 SnSb的化学组成的系统变化最大程度地减少了SnSb结构的不稳定性，并补充了重复循环过程中Sn的任何损失。组成起着至关重要的作用，因为观察到SnSb的比容量和可循环性的大小取决于Sn的可变百分比。与纯SnSb（1：1）阳极材料相比，SnSb-75-25-CF中含有过量的Sn，在100次循环后，其最高比容量为550 mAh g〜（-1），其电流密度为0.2 A g 〜（–1）并在广泛的电流密度（0.2–5 A g〜（–1））上显示出出色的速率能力。

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