Janus Separator of Polypropylene-Supported Cellular Graphene Framework for Sulfur Cathodes with High Utilization in Lithium-Sulfur Batteries.
Janus Separator of Polypropylene-Supported Cellular Graphene Framework for Sulfur Cathodes with High Utilization in Lithium-Sulfur Batteries.
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DOI：
10.1002/advs.201500268
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发表时间：
2016-01
期刊：
影响因子：
15.1
通讯作者：
Zhang, Qiang
中科院分区：
文献类型：
--
作者：
Peng, Hong-Jie;Wang, Dai-Wei;Huang, Jia-Qi;Cheng, Xin-Bing;Yuan, Zhe;Wei, Fei;Zhang, Qiang
由于硫阴极的转化化学，锂-硫（Li-S）电池表现出高的理论能量密度。然而，在硫/Li 2S至锂多硫化物固-液相变期间固有的移动的氧化还原中心导致低硫利用率和差的循环寿命。本文介绍了介孔多孔石墨烯骨架（CGF）/聚丙烯膜Janus隔膜，以促进硫阴极的利用。多孔聚丙烯膜作为与锂阳极接触的绝缘基底，而具有100 S cm-1的高电导率、3.1 cm 3 g-1的大中孔体积和2120 m2 g-1的巨大表面积的CGF粘附在阴极侧，以重新激活穿梭的多硫化物并保护离子通道。因此，具有“双面”CGF Janus隔板的Li-S电池表现出1109 mAh g−1的高初始容量和在0.2 C下250次循环后在800 mAh g−1下保持的上级容量，其硫利用效率比使用常规聚丙烯隔板的相应结果高40%。在容量以及电化学动力学方面有显著的改进。对于这种先进的配置，实现了5.5 mAh cm−2的极高面积容量，结合80%的高硫含量和5.3 mg cm−2的面积负载量。采用CGF隔膜可以很好地消除往复机构对降低锂硫电池硫利用率和总能量密度的负面影响。因此，采用含碳材料作为隔膜的两面，为改善涉及复杂相演变和转换电化学的装置的活性材料的利用率和能量密度提供了新的机会。
Owing to the conversion chemistry of the sulfur cathode, the lithium–sulfur (Li–S) batteries exhibit high theoretical energy density. However, the intrinsic mobile redox centers during the sulfur/Li2S‐to‐lithium polysulfides solid‐to‐liquid phase transition induce low sulfur utilization and poor cycling life. Herein, the Janus separator of mesoporous cellular graphene framework (CGF)/polypropylene membrane to promote the utilization of sulfur cathode is introduced. The porous polypropylene membrane serves as an insulating substrate in contact with lithium anode while CGFs that possess high electrical conductivity of 100 S cm−1, a large mesopore volume of 3.1 cm3 g−1, and a huge surface area of 2120 m2 g−1 are adhered on cathode side to reactivate the shuttling‐back polysulfides and to preserve the ion channels. Therefore, the Li–S cell with the “two‐face” CGF Janus separator exhibit a high initial capacity of 1109 mAh g−1 and superior capacity preserved upon 800 mAh g−1 after 250 cycles at 0.2 C, which is 40% higher on sulfur utilization efficiency than the corresponding results with routine polypropylene separators. There are significant improvements on capacity as well as electrochemical kinetics. A very high areal capacity of 5.5 mAh cm−2 combined with high sulfur content of 80% and areal loading amount of 5.3 mg cm−2 is achieved for such advanced configuration. The negative impact of shuttle mechanism on lowering the utilization of sulfur and overall energy density of a Li–S battery is well eliminated by applying CGF separators. Consequently, employing carbonaceous materials as Janus face of separators enlightens new opportunities for improving the utilization of active materials and energy density of devices that involve complex phase evolution and conversion electrochemistry.
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