In Situ Synthesis of Bipyramidal Sulfur with 3D Carbon Nanotube Framework for Lithium–Sulfur Batteries
In Situ Synthesis of Bipyramidal Sulfur with 3D Carbon Nanotube Framework for Lithium–Sulfur Batteries
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DOI：
10.1002/adfm.201302915
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发表时间：
2014-04
影响因子：
19
通讯作者：
Lina Wang;Yu Zhao;Morgan L. Thomas;H. Byon
中科院分区：
文献类型：
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作者：
Lina Wang;Yu Zhao;Morgan L. Thomas;H. Byon
报道了一锅法合成具有双锥硫颗粒的三维碳纳米管骨架材料及其在锂硫（Li-S）电池阴极中的应用。通过在水/四氢呋喃中简单混合多壁碳纳米管（MWCNTs）、硫粉末和封端剂，合成了被MWCNTs包围的微米双锥硫颗粒。多壁碳纳米管自发地在硫颗粒内部和外部形成3D导电网络。沿着MWCNT骨架的边缘，存在不含硫颗粒的区域，其占总体积的约35体积%。将这些硫-MWCNT双锥颗粒与导电碳添加剂混合以制备用于Li-S电池的无粘合剂阴极。Li-S电池在第一次循环时在0.05 C下的放电比容量为1600 mAh g−1。特别地，这些Li-S电池在深度放电和充电（相对于Li/Li+为1.0- 3.0V）时显示出高的速率稳定性和库仑效率。这种所得性能可以起因于1）导电MWCNT骨架和碳添加剂涂层在硫颗粒上的均匀分布，其分别允许快速Li+离子/电解质扩散和多硫化物穿梭的减轻，和2）无硫缓冲空间适应体积膨胀。预计这种具有简单合成工艺的新阴极设计可以减少制备步骤的数量，从而可以构建低成本的Li-S电池。
A one‐pot synthesis of three‐dimensional carbon nanotube frameworks with bipyramidal sulfur particles and the application of these materials for a cathode in lithium–sulfur (Li–S) battery are reported. By simple mixing of multi‐walled carbon nanotubes (MWCNTs), sulfur powder, and capping agents in water/tetrahydrofuran, micrometer bipyramidal sulfur particles enclosed with MWCNTs are synthesized. The MWCNTs spontaneously form a 3D conducting network inside and outside the sulfur particle. Along the edge of MWCNT framework, a sulfur particle‐free region is present, which comprises ≈35 vol% based on the total volume. These sulfur‐MWCNT bipyramidal particles are mixed with conductive carbon additive to prepare binder‐free cathode for Li–S cells. The Li–S cells deliver a specific discharge capacity of ≈1600 mAh g−1 at 0.05 C on the first cycle. In particular, these Li–S cells show high rate stability and Coulombic efficiency with deep discharge and charge (1.0–3.0 V vs Li/Li+). This resultant performance can arise from 1) homogeneous distribution of the conducting MWCNT framework and the carbon additive coating layer on the sulfur particle, which allow rapid Li+ ion/electrolyte diffusion and mitigation of polysulfide shuttle, respectively, and 2) the sulfur‐free buffer space accommodating volume expansion. It is expected that this new cathode design with the simple synthetic process can reduce the number of preparation steps, thus allowing the construction of a low‐cost Li–S battery.