Vertically Aligned CNT-Supported Thick Ge Films as High-Performance 3D Anodes for Lithium Ion Batteries
Vertically Aligned CNT-Supported Thick Ge Films as High-Performance 3D Anodes for Lithium Ion Batteries
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DOI：
10.1002/smll.201400003
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发表时间：
2014-07-23
期刊：
影响因子：
13.3
通讯作者：
Zhang, Qing
中科院分区：
文献类型：
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作者：
Wang, Xinghui;Susantyoko, Rahmat Agung;Zhang, Qing
由于高能量密度和长循环寿命，可充电锂离子电池(LiB)对移动设备和电动汽车的快速发展至关重要。[1-7]目前商用石墨材料的高可逆容量、长循环寿命和高倍率性能的替代阳极的开发是非常迫切的。锗(Ge)具有很高的理论比容量(约1600mAHg-1)、优异的锂离子扩散性和高的导电性，是一种很有潜力的负极材料。然而，在实际应用中，Ge在锂化和脱硫化过程中经历了很大的体积变化(超过300%)，导致活性物质从集电器上粉化和/或分离，导致失去电接触和较差的循环寿命。[11，12]人们通过制备各种纳米结构并将它们分散到活性或非活性基质中来克服这些问题。13-16]直接在集电体上生长的自支撑Ge薄膜代表了一种有吸引力的架构。例如，鲁达夫斯基等人。通过离子束修饰改善了镍箔上140-240 nm厚的Ge薄膜的电化学性能；[11，17]Wang等人。报道了一种覆盖在铜纳米线阵列上的50纳米厚的Ge薄膜，表现出了更好的性能；[18]Yu等人。在100 nm的三维双连续金电极上涂覆20 nm和50 nm厚的非晶Ge薄膜，具有较长的循环寿命和良好的倍率性能。[19]虽然这些方法显著提高了锂存储性能，但由于薄膜厚度有限，导致面积容量很小，因此很难实际应用。当使用较厚的Ge膜(>；300 nm)时，观察到快速的容量衰减。这种褪色是因为
Due to their high energy density and long cycle life, rechargeable lithium ion batteries (LIBs) are essential to the rapid development of mobile devices and electric vehicles.[1–7] Development of alternative anodes with high reversible capacity, long cycle life, and high rate capability for current commercial graphite materials is in great demand. Germanium (Ge) is of a great potential as an anode material due to its high theoretical specific capacity (ca. 1600 mAh g–1), excellent Li+ diffusivity, and high electrical conductivity.[8–10] However, in practice Ge experiences large volume changes (over 300%) during lithiation and delithiation, which result in pulverization and/or detachment of active materials from the current collector and lead to the loss of electrical contact and poor cycle life.[11, 12] Much effort has been made to overcome these problems through fabrication of various nanostructures and dispersing them into active or inactive host matrices.[10, 13–16] Self-supported Ge thin films grown directly on current collectors, represent an attractive architecture. For instance, Rudawski et al. improved the electrochemical performance of 140–240-nm-thick Ge thin film on Ni foil through ion-beam modification;[11, 17] Wang et al. reported a 50-nm-thick Ge thin film covering copper nanowire arrays that showed improved performance;[18] Yu et al. coated 20-and 50-nm-thick amorphous Ge thin film on 100-nm three-dimensional (3D) bicontinuous Au electrodes, which delivered long cycle life and good rate performance.[19] Although these methods significantly enhance lithium-storage performance, they are hard to apply practically because the limited film thickness results in a small areal capacity. When thicker Ge film (> 300 nm) is used, fast capacity fading is observed. This fading is because there is