State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, PR China.
ACS Appl Mater Interfaces. 2013 Mar;5(6):2208-13. doi: 10.1021/am4000535. Epub 2013 Mar 15.
Porous carbon materials with large pore volume are crucial in loading insulated sulfur with the purpose of achieving high performance for lithium-sulfur batteries. In our study, peapodlike mesoporous carbon with interconnected pore channels and large pore volume (4.69 cm(3) g(-1)) was synthesized and used as the matrix to fabricate carbon/sulfur (C/S) composite which served as attractive cathodes for lithium-sulfur batteries. Systematic investigation of the C/S composite reveals that the carbon matrix can hold a high but suitable sulfur loading of 84 wt %, which is beneficial for improving the bulk density in practical application. Such controllable sulfur-filling also effectively allows the volume expansion of active sulfur during Li(+) insertion. Moreover, the thin carbon walls (3-4 nm) of carbon matrix not only are able to shorten the pathway of Li(+) transfer and conduct electron to overcome the poor kinetics of sulfur cathode, but also are flexible to warrant structure stability. Importantly, the peapodlike carbon shell is beneficial to increase the electrical contact for improving electronic conductivity of active sulfur. Meanwhile, polymer modification with polypyrrole coating layer further restrains polysulfides dissolution and improves the cycle stability of carbon/sulfur composites.
具有大孔体积的多孔碳材料对于负载绝缘硫以实现高性能的锂硫电池至关重要。在我们的研究中，合成了具有互联孔道和大孔体积（4.69cm3g-1）的豆荚状介孔碳，并将其用作基质来制备碳/硫（C/S）复合材料，该复合材料作为锂硫电池有吸引力的阴极。对 C/S 复合材料的系统研究表明，碳基质可以容纳高达 84wt%的高但合适的硫负载量，这有利于提高实际应用中的堆积密度。这种可控的硫填充还可以有效地阻止活性硫在 Li（+）插入过程中的体积膨胀。此外，碳基质的薄碳壁（3-4nm）不仅能够缩短 Li（+）转移的路径并传导电子以克服硫阴极的差动力学，而且还具有灵活性以保证结构稳定性。重要的是，豆荚状碳壳有利于增加电接触，从而提高活性硫的电子导电性。同时，用聚吡咯涂层进行聚合物修饰进一步抑制多硫化物的溶解，提高了碳/硫复合材料的循环稳定性。
