Smaller Sulfur Molecules Promise Better Lithium-Sulfur Batteries
Smaller Sulfur Molecules Promise Better Lithium-Sulfur Batteries
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DOI：
10.1021/ja308170k
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发表时间：
2012-11-14
影响因子：
15
通讯作者：
Wan, Li-Jun
中科院分区：
文献类型：
--
作者：
Xin, Sen;Gu, Lin;Wan, Li-Jun
锂硫电池具有很高的理论能量密度，是目前锂离子电池的4-5倍，但其应用一直受到劣质电池的阻碍。硫磺阴极的电子传导性下降，最重要的是，由于形成了可溶的多硫化物中间体(Li2Sn4-8)，导致其容量迅速衰减。尽管在这个问题上作出了许多努力，但打击硫损失仍然是最大的挑战之一。在这里，我们表明，通过将硫控制为较小的同素异形体，这个问题可以有效地减少。在导电微孔碳基质的受限空间中合成了亚稳的S2-4小分子硫分子。约束S2-4作为一种新型正极材料，可以完全避免常用的大尺寸S-8和S-4(2-)之间的不利过渡。基于这一概念的锂S电池具有前所未有的高比容量、良好的循环稳定性和优异的倍率性能，有望成为一种实用的高能量密度电池，应用于便携式电子产品、电动汽车和大规模储能系统。
The lithium-sulfur battery holds a high theoretical energy density, 4-5 times that of today's lithium ion batteries, yet its applications have been hindered by poor. electronic conductivity of the sulfur Cathode and, most importantly, the rapid fading of its capacity due, to the formation of soluble polysulfide intermediates (Li2Sn, n = 4-8). Despite numerous efforts concerning this issue, combatting sulfur loss remains one of the greatest challenges. Here we show that this problem can be effectively diminished by controlling the sulfur as smaller allotropes. Metastable small sulfur molecules of S2-4 were synthesized in the confined space of a conductive microporous carbon matrix. The confined S2-4 as a new cathode material can totally avoid the unfavorable transition between the commonly used large S-8 and S-4(2-). Li-S batteries based on this concept exhibit unprecedented electrochemical behavior with high specific capacity, good cycling stability, and superior rate capability, which promise a practicable battery with high energy density for applications in portable electronics, electric vehicles, and large-scale energy storage systems.