Department of Chemical and Biomolecular Engineering, University of Maryland , College Park, Maryland 20742, United States.
Institute for Superconducting and Electronic Materials, University of Wollongong , Wollongong, NSW 2522, Australia.
ACS Nano. 2017 Sep 26;11(9):9048-9056. doi: 10.1021/acsnano.7b03591. Epub 2017 Sep 5.
Due to its high theoretical capacity, high energy density, and easy availability, the lithium-sulfur (Li-S) system is considered to be the most promising candidate for electric and hybrid electric vehicle applications. Sulfur/carbon cathode in Li-S batteries still suffers, however, from low Coulombic efficiency and poor cycle life when sulfur loading and the ratio of sulfur to carbon are high. Here, we address these challenges by fabricating a sulfur/carboxylated-graphene composite using a reverse (water-in-oil) microemulsion technique. The fabricated sulfur-graphene composite cathode, which contains only 6 wt % graphene, can dramatically improve the cycling stability as well as provide high capacity. The electrochemical performance of the sulfur-graphene composite is further enhanced after loading into a three-dimensional heteroatom-doped (boron and nitrogen) carbon-cloth current collector. Even at high sulfur loading (∼8 mg/cm) on carbon cloth, this composite showed 1256 mAh/g discharge capacity with more than 99% capacity retention after 200 cycles.
由于其理论容量高、能量密度高、易于获得，锂硫（Li-S）系统被认为是最有前途的电动和混合动力汽车应用候选者。然而，当硫的负载和硫与碳的比例较高时，硫/碳阴极在锂硫电池中仍然存在库仑效率低和循环寿命差的问题。在这里，我们通过使用反相（油包水）微乳液技术来制造一种羧基化石墨烯复合硫。所制备的含 6wt%石墨烯的硫-石墨烯复合阴极可以显著提高循环稳定性并提供高容量。将硫-石墨烯复合材料装入三维杂原子掺杂（硼和氮）碳布集流器后，其电化学性能得到进一步提高。即使在碳布上的硫负载量较高（约 8mg/cm）的情况下，该复合材料在 200 次循环后仍具有 1256mAh/g 的放电容量，容量保持率超过 99%。
