Zhang Qingfei, Qiao Zhensong, Cao Xinrui, Qu Baihua, Yuan Jin, Fan Tian-E, Zheng Hongfei, Cui Jinqing, Wu Shunqing, Xie Qingshui, Peng Dong-Liang
Department of Materials Science and Engineering, College of Materials and Pen-Tung Sah Institute of Micro-Nano Science and Technology, State Key Lab of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials, Fujian Provincial Key Laboratory of Materials Genome, Xiamen University, Xiamen 361005, P. R. China.
Nanoscale Horiz. 2020 Apr 1;5(4):720-729. doi: 10.1039/c9nh00663j. Epub 2020 Feb 13.
Spatial confinement is a desirable successful strategy to trap sulfur within its porous host and has been widely applied in lithium-sulfur (Li-S) batteries. However, physical confinement alone is currently not enough to reduce the lithium polysulfide (LiS, 4 ≤n≤ 8, LIPSs) shuttle effect with sluggish LIPS-dissolving kinetics. In this work, we have integrated spatial confinement with a polar catalyst, and designed a three-dimensional (3D) interconnected, Co decorated and N doped porous carbon nanofiber (Co/N-PCNF) network. This Co/N-PCNF film serves as a freestanding host for sulfur trapping, which could effectively facilitate the infiltration of electrolyte and electron transport. In addition, the polar Co species possess strong chemisorption with LIPSs, catalyzing their reaction kinetics as well. As a result of this rational design and integration, the Co/N-PCNF@S cathode with a sulfur loading of 2 mg cm exhibits a high initial discharge capacity of 878 mA h g at 1C, and maintains a discharge capacity of 728 mA h g after 200 cycles. Even with high sulfur loading of 9.33 mg cm, the cathode still keeps a stable areal capacity of 7.16 mA h cm at 0.2C after 100 cycles, which is much higher than the current areal capacity (4 mA h cm) of commercialized lithium-ion batteries (LIBs). This rational design may provide a new approach for future development of high-density Li-S batteries with high sulfur loading.
空间限域是一种将硫捕获在其多孔主体内的理想成功策略，已广泛应用于锂硫（Li-S）电池。然而，目前仅靠物理限域不足以减少多硫化锂（LiS，4≤n≤8，LIPSs）的穿梭效应，且LIPS溶解动力学缓慢。在这项工作中，我们将空间限域与极性催化剂相结合，设计了一种三维（3D）互连、钴修饰且氮掺杂的多孔碳纳米纤维（Co/N-PCNF）网络。这种Co/N-PCNF薄膜用作捕获硫的独立主体，可有效促进电解质的渗透和电子传输。此外，极性钴物种与LIPSs具有强烈的化学吸附作用，也催化了它们的反应动力学。由于这种合理的设计和整合，硫负载量为2 mg cm的Co/N-PCNF@S阴极在1C下表现出878 mA h g的高初始放电容量，在200次循环后保持728 mA h g的放电容量。即使硫负载量高达9.33 mg cm，该阴极在100次循环后在0.2C下仍保持7.16 mA h cm的稳定面积容量，远高于商业化锂离子电池（LIBs）目前的面积容量（4 mA h cm）。这种合理设计可能为未来开发高硫负载的高密度Li-S电池提供一种新方法。
