Xiao Kuikui, Wang Jin, Chen Zhen, Qian Yuhong, Liu Zheng, Zhang Lili, Chen Xiaohua, Liu Jilei, Fan Xiaofeng, Shen Ze Xiang
College of Materials Science and Engineering, Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, Hunan University, Changsha, 410082, China.
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.
Small. 2019 Jun;15(25):e1901454. doi: 10.1002/smll.201901454. Epub 2019 May 9.
Improved conductivity and suppressed dissolution of lithium polysulfides is highly desirable for high-performance lithium-sulfur (Li-S) batteries. Herein, by a facile solvent method followed by nitridation with NH , a 2D nitrogen-doped carbon structure is designed with homogeneously embedded Co N nanoparticles derived from metal organic framework (MOF), grown on the carbon cloth (MOF-Co N). Experimental results and theoretical simulations reveal that Co N nanoparticles act as strong chemical adsorption hosts and catalysts that not only improve the cycling performance of Li-S batteries via chemical bonding to trap polysulfides but also improve the rate performance through accelerating the conversion reactions by decreasing the polarization of the electrode. In addition, the high conductive nitrogen-doped carbon matrix ensures fast charge transfer, while the 2D structure offers increased pathways to facilitate ion diffusion. Under the current density of 0.1C, 0.5C, and 3C, MOF-Co N delivers reversible specific capacities of 1425, 1049, and 729 mAh g , respectively, and retains 82.5% capacity after 400 cycles at 1C, as compared to the sample without Co N (MOF-C) values of 61.3% (200 cycles). The improved cell performance corroborates the validity of the multifunctional design of MOF-Co N, which is expected to be a potentially promising cathode host for Li-S batteries.
对于高性能锂硫（Li-S）电池而言，提高导电性并抑制多硫化锂的溶解是非常必要的。在此，通过一种简便的溶剂法，随后用NH 进行氮化处理，设计出了一种二维氮掺杂碳结构，其中均匀嵌入了源自金属有机框架（MOF）的Co N纳米颗粒，并生长在碳布上（MOF-Co N）。实验结果和理论模拟表明，Co N纳米颗粒作为强大的化学吸附主体和催化剂，不仅通过化学键合捕获多硫化物来提高Li-S电池的循环性能，还通过降低电极极化加速转化反应来提高倍率性能。此外，高导电性的氮掺杂碳基体确保了快速的电荷转移，而二维结构提供了更多促进离子扩散的通道。在0.1C、0.5C和3C的电流密度下，MOF-Co N分别提供1425、1049和729 mAh g 的可逆比容量，在1C下循环400次后保留82.5%的容量，相比之下，不含Co N的样品（MOF-C）在200次循环后的容量保持率为61.3%。电池性能的提升证实了MOF-Co N多功能设计的有效性，有望成为Li-S电池极具潜力的正极主体材料。
