Enhancement of long stability of sulfur cathode by encapsulating sulfur into micropores of carbon spheres
Enhancement of long stability of sulfur cathode by encapsulating sulfur into micropores of carbon spheres
复制标题
将硫包裹在碳球微孔中提高硫阴极的长期稳定性
DOI：
10.1039/c002639e
复制
发表时间：
2010-01-01
影响因子：
32.5
通讯作者：
Gao, X. P.
中科院分区：
文献类型：
--
作者：
Zhang, B.;Qin, X.;Gao, X. P.
为了提高高能锂硫电池系统硫阴极的长期稳定性，将升华硫与碳球的混合物进行热处理，将硫包埋在碳球的微孔中，制备了硫碳球复合材料。通过x射线粉末衍射（XRD）、透射电子显微镜（TEM）、布鲁瑙尔-埃米特-泰勒（BET）、热重（TG）和局部元素线扫描等分析，发现单元素硫在表面积大、孔分布窄的碳球微孔内以高度分散的状态存在。恒流充放电过程、循环伏安（CV）和电化学阻抗谱（EIS）表明，硫碳球复合材料作为正极材料具有较大的可逆容量和优良的高倍率放电性能。特别是含硫量为42 wt%的硫碳球复合材料，由于碳球的强吸附作用，在狭窄的微孔内约束了电化学反应，因此具有长达500次循环的长电化学稳定性。因此，本文提出的限制在微孔内的电化学反应将是硫阴极长期稳定性增强的主要因素。本研究获得的知识不仅对设计高效的新型电极材料具有重要意义，而且对理解微孔对电化学循环稳定性的影响具有重要意义。
To enhance the long stability of sulfur cathode for a high energy lithium-sulfur battery system, a sulfur-carbon sphere composite was prepared by encapsulating sulfur into micropores of carbon spheres by thermal treatment of a mixture of sublimed sulfur and carbon spheres. The elemental sulfur exists as a highly dispersed state inside the micropores of carbon spheres with a large surface area and a narrow pore distribution, based on the analyses of the X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), thermogravimetry (TG) and local element line-scanning. It is demonstrated from galvanostatic discharge-charge process, cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) that the sulfur-carbon sphere composite has a large reversible capacity and an excellent high rate discharge capability as cathode materials. In particular, the sulfur-carbon sphere composite with 42 wt% sulfur presents a long electrochemical stability up to 500 cycles, based on the constrained electrochemical reaction inside the narrow micropores of carbon spheres due to strong adsorption. Therefore, the electrochemical reaction constrained inside the micropores proposed here would be the dominant factor for the enhanced long stability of the sulfur cathode. The knowledge acquired in this study is important not only for the design of efficient new electrode materials, but also for understanding the effect of the micropores on the electrochemical cycle stability.