Materials Science Institute, PCFM Lab and GDHPRC Lab, School of Chemistry, Sun Yat-sen University, Guangzhou, 510275, P. R. China.
Laboratory for Computational Materials Engineering, Division of Energy and Environment, Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, P. R. China.
Adv Mater. 2018 Mar;30(12):e1706895. doi: 10.1002/adma.201706895. Epub 2018 Feb 9.
Lithium-sulfur (Li-S) batteries, based on the redox reaction between elemental sulfur and lithium metal, have attracted great interest because of their inherently high theoretical energy density. However, the severe polysulfide shuttle effect and sluggish reaction kinetics in sulfur cathodes, as well as dendrite growth in lithium-metal anodes are great obstacles for their practical application. Herein, a two-in-one approach with superhierarchical cobalt-embedded nitrogen-doped porous carbon nanosheets (Co/N-PCNSs) as stable hosts for both elemental sulfur and metallic lithium to improve their performance simultaneously is reported. Experimental and theoretical results reveal that stable Co nanoparticles, elaborately encapsulated by N-doped graphitic carbon, can work synergistically with N heteroatoms to reserve the soluble polysulfides and promote the redox reaction kinetics of sulfur cathodes. Moreover, the high-surface-area pore structure and the Co-enhanced lithiophilic N heteroatoms in Co/N-PCNSs can regulate metallic lithium plating and successfully suppress lithium dendrite growth in the anodes. As a result, a full lithium-sulfur cell constructed with Co/N-PCNSs as two-in-one hosts demonstrates excellent capacity retention with stable Coulombic efficiency.
锂硫（Li-S）电池基于元素硫和金属锂之间的氧化还原反应，由于其固有的高理论能量密度而引起了极大的兴趣。然而，硫正极中严重的多硫化物穿梭效应和缓慢的反应动力学，以及锂金属负极中的枝晶生长，是其实际应用的巨大障碍。在此，报道了一种将超分级钴嵌入氮掺杂多孔碳纳米片（Co/N-PCNSs）作为同时改善其性能的元素硫和金属锂的稳定主体的二合一方法。实验和理论结果表明，由氮掺杂石墨碳精心封装的稳定 Co 纳米颗粒可以与 N 杂原子协同作用，保留可溶性多硫化物并促进硫正极的氧化还原反应动力学。此外，Co/N-PCNSs 中的高表面积孔结构和 Co 增强的亲锂 N 杂原子可以调节金属锂电镀，并成功抑制负极中的锂枝晶生长。因此，用 Co/N-PCNSs 作为二合一主体构建的全锂硫电池表现出优异的容量保持率和稳定的库仑效率。
