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β-SnSb for Sodium Ion Battery Anodes: Phase Transformations Responsible for Enhanced Cycling Stability Revealed by In Situ TEM
ACS Energy Letters ( IF 19.3 ) Pub Date : 2018-06-19 00:00:00 , DOI: 10.1021/acsenergylett.8b00762
Hezhen Xie 1, 2 , Xuehai Tan 3 , Erik J. Luber 1, 2 , Brian C. Olsen 1, 2 , W. Peter Kalisvaart 1, 2 , Katherine L. Jungjohann 4 , David Mitlin 5 , Jillian M. Buriak 1, 2
Affiliation  

β-SnSb is known to be a highly stable anode for sodium ion batteries during cycling, but its sodiation–desodiation alloying reactions are poorly understood. Combining in situ TEM with electroanalytical methods, we demonstrate that β-SnSb forms Na3Sb and Na15Sn4 in sequence upon sodiation and re-forms as β-SnSb upon desodiation. The negative enthalpy of mixing for Sn and Sb is sufficient to cause sequentially deposited bilayers of Sn/Sb to transform into β-SnSb, resulting in comparable cycling stability. The good cycling stability of β-SnSb results from the complex two-phase amorphous–nanocrystalline microstructure in the partially charged–discharged states, as well as the intrinsic mechanical toughness of the β phase. Per the in situ TEM results, the sequential phase transformation shows minimal fracturing of the β-SnSb, indicating facile buffering of stresses. Extensively cycled specimens eventually show crystalline Sn phase segregation, which may be the source of the ultimate capacity fade in the alloy and bilayers.

中文翻译:

用于钠离子电池阳极的β-SnSb:通过原位TEM揭示了增强循环稳定性的相变

众所周知,β-SnSb是钠离子电池在循环过程中高度稳定的阳极,但其对钠盐-钠盐的合金化反应知之甚少。将原位TEM与电分析方法相结合,我们证明β-SnSb形成Na 3 Sb和Na 15 Sn 4在糖化过程中顺序排列,在糖化过程中重新形成β-SnSb。Sn和Sb的混合负焓足以引起顺序沉积的Sn / Sb双层转变为β-SnSb,从而具有相当的循环稳定性。β-SnSb的良好循环稳定性来自于部分充放电状态下复杂的两相非晶-纳米晶体微观结构以及β相的固有机械韧性。根据原位TEM结果,顺序相变显示β-SnSb的断裂最小,表明应力的缓冲很容易。大量循环的样本最终显示出结晶的Sn相偏析,这可能是合金和双层中最终容量衰减的来源。
更新日期:2018-06-19
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