Polydopamine-coated, nitrogen-doped, hollow carbon-sulfur double-layered core-shell structure for improving lithium-sulfur batteries.
Polydopamine-coated, nitrogen-doped, hollow carbon-sulfur double-layered core-shell structure for improving lithium-sulfur batteries.
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DOI：
10.1021/nl502238b
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发表时间：
2014-08
期刊：
影响因子：
10.8
通讯作者：
Weidong Zhou;Xingcheng Xiao;Mei Cai;Li Yang
中科院分区：
文献类型：
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作者：
Weidong Zhou;Xingcheng Xiao;Mei Cai;Li Yang
为了更好地限制锂硫(Li/S)电池电极中的硫/多硫化物，提高循环稳定性，我们研制了聚合物包覆碳硫双层核壳结构。首先将硫磺浸渍到中空碳球中，然后进行包覆聚合，得到双层核壳结构。通过对扫描电子显微镜(STEM)图像的研究，我们证明了硫不仅成功地穿透了多孔碳壳，而且还沿着碳壳内壁聚集，这首次提供了可见和令人信服的证据，证明硫更倾向于扩散到中空碳中，而不是聚集在多孔壁上。利用这种结构，在Li/S电池中，150次循环后0.2℃下的容量稳定在900 mA h g(-1)，600次循环后0.6 C下的容量稳定在630 mA h g(-1)。我们还论证了全电池使用硫电极与硅膜电极耦合的可行性，这表明显著提高了循环稳定性和效率。这种出色的电化学性能可以归因于通过独特的双层核壳结构对硫的良好限制。
To better confine the sulfur/polysulfides in the electrode of lithium-sulfur (Li/S) batteries and improve the cycling stability, we developed a double-layered core-shell structure of polymer-coated carbon-sulfur. Carbon-sulfur was first prepared through the impregnation of sulfur into hollow carbon spheres under heat treatment, followed by a coating polymerization to give a double-layered core-shell structure. From the study of scanning transmission electron microscopy (STEM) images, we demonstrated that the sulfur not only successfully penetrated through the porous carbon shell but also aggregated along the inner wall of the carbon shell, which, for the first time, provided visible and convincing evidence that sulfur preferred diffusing into the hollow carbon rather than aggregating in/on the porous wall of the carbon. Taking advantage of this structure, a stable capacity of 900 mA h g(-1) at 0.2 C after 150 cycles and 630 mA h g(-1) at 0.6 C after 600 cycles could be obtained in Li/S batteries. We also demonstrated the feasibility of full cells using the sulfur electrodes to couple with the silicon film electrodes, which exhibited significantly improved cycling stability and efficiency. The remarkable electrochemical performance could be attributed to the desirable confinement of sulfur through the unique double-layered core-shell architectures.