Alloying of Alkali Metals with Tellurene
Alloying of Alkali Metals with Tellurene
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DOI：
10.1002/aenm.202003248
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发表时间：
2020-08
影响因子：
27.8
通讯作者：
Dhruv Batra;Yifei Yuan;Y. Singh;Swastik Basu;Dawei Wang;A. Yang;Xiaohua Wang;M. Rong;Ho Jin Le
中科院分区：
文献类型：
--
作者：
Dhruv Batra;Yifei Yuan;Y. Singh;Swastik Basu;Dawei Wang;A. Yang;Xiaohua Wang;M. Rong;Ho Jin Le
石墨阳极在锂离子电池中提供较低的容量。相比之下，碲有望与具有高体积容量的碱金属(≈2620mAhcm−3)合金化，但到目前为止还没有对其合金化行为的详细研究。本文研究了一系列含少量Te的碱金属(A=Li、Na、K)的合金化反应。原位电子显微镜和密度泛函理论都表明，Te与碱金属形成了A2Te。然而，合金产品的结晶顺序从单晶(对于Li2Te)到多晶(对于Na2Te和K2Te)有很大的不同。典型的合金材料在与锂反应时会失去结晶度--因此，Te保持结晶度的能力令人惊讶。模拟表明，与Na或K相比，Li在Te中的迁移是高度各向同性的，使其结晶度得以保持。这种各向同性的锂输运是由Te的特殊结构实现的，其中手性链由范德华力束缚。而与Na和K的合金化性能较差，而在Li中，Te的体积容量稳定在≈700mAhcm−3，约为商品石墨实际容量的两倍。
Graphite anodes offer low volumetric capacity in lithium‐ion batteries. By contrast, tellurene is expected to alloy with alkali metals with high volumetric capacity (≈2620 mAh cm−3), but to date there is no detailed study on its alloying behavior. In this work, the alloying response of a range of alkali metals (A = Li, Na, or K) with few‐layer Te is investigated. In situ transmission electron microscopy and density functional theory both indicate that Te alloys with alkali metals forming A2Te. However, the crystalline order of alloyed products varies significantly from single‐crystal (for Li2Te) to polycrystalline (for Na2Te and K2Te). Typical alloying materials lose their crystallinity when reacted with Li—the ability of Te to retain its crystallinity is therefore surprising. Simulations reveal that compared to Na or K, the migration of Li is highly “isotropic” in Te, enabling its crystallinity to be preserved. Such isotropic Li transport is made possible by Te's peculiar structure comprising chiral‐chains bound by van der Waals forces. While alloying with Na and K show poor performance, with Li, Te exhibits a stable volumetric capacity of ≈700 mAh cm−3, which is about twice the practical capacity of commercial graphite.