Microstructural Evolution of Tin Nanoparticles during In Situ Sodium Insertion and Extraction
Microstructural Evolution of Tin Nanoparticles during In Situ Sodium Insertion and Extraction
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DOI：
10.1021/nl303305c
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发表时间：
2012-11-01
期刊：
影响因子：
10.8
通讯作者：
Huang, Jian Yu
中科院分区：
文献类型：
--
作者：
Wang, Jiang Wei;Liu, Xiao Hua;Huang, Jian Yu
利用原位透射电镜研究了纳米钠离子电池电解过程中锡纳米粒子的微观结构变化和相变。研究发现，第一个调解过程分两步进行；即结晶Sn纳米粒子最初是通过具有迁移相边界的两相机制介导形成na贫的非晶态NaxSn合金（x近似于0.5），再通过单相机制介导形成几个富na的非晶态Na15Sn4 （x = 3.75）。第一步的体积膨胀率约为60%，第二步后的体积膨胀率为420%。然而，尽管出现了巨大的膨胀，但并未观察到裂纹或断裂，这是由于单相钠化的第二步，在整个颗粒上容纳了很大一部分钠化引起的应力。在可逆的钠/脱钠循环过程中也观察到优异的可循环性，显示了锡纳米粒子作为可充电电池电极材料的巨大潜力。
The microstructural changes and phase transformations of tin nanoparticles during electrochemical sodiation were studied with a nanosized sodium ion battery using in situ transmission electron microscopy. It was found that the first sodiation process occurred in two steps; that is, the crystalline Sn nanoparticles were initially sodiated via a two-phase mechanism with a migrating phase boundary to form a Na-poor, amorphous NaxSn alloy (x similar to 0.5), which was further sodiated to several Na-rich amorphous phases and finally to the crystallized Na15Sn4 (x = 3.75) via a single-phase mechanism. The volumetric expansion was about 60% in the first step and 420% after the second step. However, despite the huge expansion, cracking or fracture was not observed, which is attributed to the second step of the single-phase sodiation that accommodates large portion of the sodiation-induced stress over the entire particle. Excellent cyclability was also observed during the reversible sodiation/desodiation cycles, showing great potential of Sn nanoparticles as a robust electrode material for rechargeable batteries.