Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University , 145 Gwanggyo-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-270, Republic of Korea.
Advanced Institutes of Convergence Technology , 145 Gwanggyo-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-270, Republic of Korea.
ACS Appl Mater Interfaces. 2017 Jan 25;9(3):2430-2438. doi: 10.1021/acsami.6b13370. Epub 2017 Jan 10.
There is a growing need to improve the electrical conductivity of the cathode and to suppress the rapid capacity decay during cycling in lithium-sulfur (Li-S) batteries. This can be achieved by developing facile methods for the synthesis of novel nanostructured carbon materials that can function as effective cathode hosts. In this Article, we report the scalable synthesis of ordered mesoporous carbon nanosheets (OMCNS) via the etching of self-assembled iron oxide/carbon hybrid nanosheets (IO-C NS), which serve as an advanced sulfur host for Li-S batteries. The obtained two-dimensional (2D) nanosheets have close-packed uniform cubic mesopores of ∼20 nm side length, and the gap between the pores is ∼4 nm, which resembles the honeycomb structure consisting of an ordered array of hexagonal pores. We loaded OMCNS with sulfur by a simple melting infusion process and evaluated the performance of the resulting OMCNS-sulfur composites as the cathode material. As a result, the sulfur-loaded OMCNS hybrid (OMCNS-S) electrode infiltrated with 70 wt % sulfur delivers a high and stable reversible capacity of 505.7 mA h g after 500 cycles at 0.5 C-rate with excellent capacity retention (a decay of 0.081% per cycle) and excellent rate capability (580.6 mA h g at a high current density of 2 C). The improved electrochemical properties could be attributed to the fact that the uniform cubic mesopores offer sufficient space for the volume expansion of sulfur inside them and therefore trap the polysulfides during the charging-discharging process. Therefore, these unique structured carbon nanosheets can be promising candidates for other energy-storage applications.
在锂硫（Li-S）电池中，阴极的导电性需要提高，循环过程中的容量快速衰减需要得到抑制。这可以通过开发简便的方法来合成新型纳米结构的碳材料来实现，这些材料可以作为有效的阴极主体。在本文中，我们报告了通过自组装的氧化铁/碳混合纳米片（IO-C NS）的刻蚀，可大规模合成有序介孔碳纳米片（OMCNS）的方法，IO-C NS 可用作 Li-S 电池的先进硫主体。所得到的二维（2D）纳米片具有紧密堆积的均匀立方介孔，边长约为 20nm，孔之间的间隙约为 4nm，类似于由有序排列的六边形孔组成的蜂窝状结构。我们通过简单的熔融渗透过程将 OMCNS 负载硫，并评估了所得的 OMCNS-硫复合材料作为阴极材料的性能。结果表明，负载 70wt%硫的 OMCNS 杂化物（OMCNS-S）电极在 0.5 C 倍率下经过 500 次循环后，具有 505.7 mA h g-1 的高且稳定的可逆容量，具有出色的容量保持率（每循环衰减 0.081%）和优异的倍率性能（在 2 C 的高电流密度下为 580.6 mA h g-1）。电化学性能的提高可归因于以下事实：均匀的立方介孔为硫在其中的体积膨胀提供了足够的空间，并因此在充电-放电过程中捕获多硫化物。因此，这些独特结构的碳纳米片有望成为其他储能应用的候选材料。
