Polysulfide Anchoring Mechanism Revealed by Atomic Layer Deposition of V2O5 and Sulfur-Filled Carbon Nanotubes for Lithium-Sulfur Batteries.
Polysulfide Anchoring Mechanism Revealed by Atomic Layer Deposition of V2O5 and Sulfur-Filled Carbon Nanotubes for Lithium-Sulfur Batteries.
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DOI：
10.1021/acsami.6b16155
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发表时间：
2017-02
影响因子：
9.5
通讯作者：
R. Carter;L. Oakes;N. Muralidharan;Adam P. Cohn;Anna Douglas;C. Pint
中科院分区：
文献类型：
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作者：
R. Carter;L. Oakes;N. Muralidharan;Adam P. Cohn;Anna Douglas;C. Pint
尽管表面工程有望解决硫碳复合材料阴极中多硫化物穿梭的挑战，但熔融渗透技术限制了工程表面与多硫化物锚定相关的机理研究。在这里，我们提出了一个受控的实验证明，在组装成无粘合剂电极和极性V2O5锚定层的原子层沉积（ALD）涂层后，使用气相等温处理来填充碳纳米管（CNTs）的内部。碳纳米管外表面的超薄亚单层V2O5涂层平衡了多硫化物穿梭的不利影响和由于导电碳纳米管表面附近的结合位点而导致的高硫利用率的必要性。装载到碳纳米管内部的硫提供了一个空间分离的控制体积，通过直接的硫-碳纳米管电接触实现高硫负载，从而实现有效的硫转化。通过控制ALD涂层厚度，在0.1℃和0.2℃条件下获得1209 mAh/gS的高初始放电容量，在100次循环后保持87%的容量，在450次循环时保持73%的容量，并与最佳的V2O5锚定层厚度相关。这提供了实验证据，表明表面工程方法可以通过控制设计高效无粘结剂锂硫电池阴极的分子尺度构建块来有效克服多硫穿梭。
Despite the promise of surface engineering to address the challenge of polysulfide shuttling in sulfur-carbon composite cathodes, melt infiltration techniques limit mechanistic studies correlating engineered surfaces and polysulfide anchoring. Here, we present a controlled experimental demonstration of polysulfide anchoring using vapor phase isothermal processing to fill the interior of carbon nanotubes (CNTs) after assembly into binder-free electrodes and atomic layer deposition (ALD) coating of polar V2O5 anchoring layers on the CNT surfaces. The ultrathin submonolayer V2O5 coating on the CNT exterior surface balances the adverse effect of polysulfide shuttling with the necessity for high sulfur utilization due to binding sites near the conductive CNT surface. The sulfur loaded into the CNT interior provides a spatially separated control volume enabling high sulfur loading with direct sulfur-CNT electrical contact for efficient sulfur conversion. By controlling ALD coating thickness, high initial discharge capacity of 1209 mAh/gS at 0.1 C and exceptional cycling at 0.2 C with 87% capacity retention after 100 cycles and 73% at 450 cycles is achieved and correlated to an optimal V2O5 anchoring layer thickness. This provides experimental evidence that surface engineering approaches can be effective to overcome polysulfide shuttling by controlled design of molecular-scale building blocks for efficient binder free lithium sulfur battery cathodes.