钴修饰碳纳米管瓶刷助力锂硫电池多硫化物转化

开发具有多层次结构(包括多孔结构、杂化骨架和/或拓扑形貌)的超结构碳材料,对于满足电化学储能和转换系统中复杂催化反应的需求非常关键.在本文中,我们以钴纳米颗粒为催化位点,在杂化碳纳米管骨架表面可控接枝毛发状碳纳米管,开发了一类层次化多孔的钴修饰碳纳米管瓶刷(Co/CNTBs).其中,精确的瓶刷状拓扑形貌和分级多孔结构能够有效地提供可及表/界面和高导电网络,钴修饰的杂化骨架可以促进硫的氧化还原反应动力学.因此,基于Co/CNTBs功能化隔膜的锂硫电池具有优异的倍率性能(在10 C下比容量为707 mA h g^(-1))和长效的循环稳定性.更重要的是,基于Co/CNTBs催化剂的高硫载量电池(6.72 mg cm^(-2))在0.1 C下循环100圈后仍具有4.81 mA h cm^(-2)的高面积容量.本工作为高性能超结构杂化碳材料的原位接枝合成策略带来了新的思路,有望用于众多具有挑战性的应用.

Oxygen-vacancy-containing cerium oxide nanoparticle-decorated nanonetwork-structured carbon toward high-performance lithium–sulfur batteries

Lithium-sulfur(Li-S)batteries have been regarded as promising next-generation energy-storage devices owing to their inherently high theoretical energy density.Unfortunately,the poor capacity and cycling life caused by severe polysulfide shuttle effect and sluggish redox kinetics in sulfur cathodes greatly impede the practical application of Li-S batteries.Herein,a new class of nanonetworkstructured carbon decorated with oxygen-vacancy-containing cerium oxide nanoparticles(NSC-CeO_(2−x)),in which carbon skeleton is composed of highly conductive carbon nanotube core welded by hybrid carbon shell,has been developed via one-step heating treatment of hybrid molecular brush and further employed as functional interlayer to modify separator of Li-S battery.Owing to the synergistic effect of the highly active CeO_(2−x)nanoparticles and the threedimensional carbon nanonetwork in enhancing the preservation of the soluble polysulfides and boosting the redox kinetics of sulfur species,the NSC-CeO_(2−x)significantly promotes the electrochemical performance of sulfur cathode.As a result,the as-constructed Li-S batteries exhibit an ultrahigh initial sulfur utilization of 92.9%and an extremely large capacity of 751mA h g^(−1) at a high rate of 5 C.Remarkably,a stable capacity of 728 mA h g^(−1)over 300 cycles at 1 C is also achieved.