Peng Lin, Yu Zhanjiang, Zhang Mingkun, Zhen Shunying, Shen Junhao, Chang Yu, Wang Yi, Deng Yuanfu, Li Aiju
School of Chemistry, South China Normal University, Guangzhou, 510006, China.
School of Environment, South China Normal University, Guangzhou, 510006, China.
Nanoscale. 2021 Oct 14;13(39):16696-16704. doi: 10.1039/d1nr04855d.
Lithium sulfur (Li-S) batteries represent one of the most promising future power batteries due to their remarkable advantages of low cost and ultrahigh theoretical energy density. However, the commercial applications of Li-S batteries have long been plagued by the shuttling effect of polysulfides and sluggish redox kinetics of these species. Herein, we designed a novel battery separator coated by a europium oxide-doped porous Ketjen Black (EuO/KB) and tested its performance for the Li-S batteries for the first time. Experimental results and theoretical calculations reveal that the improved electrochemical performance can be attributed to the presence of EuO. The strong binding effect between EuO and polysulfides is demonstrated in two aspects: (1) there exist strong interactions between EuO as a Lewis acid and polysulfides of strong Lewis basicity; (2) EuO with oxygen-vacancy defects provides active sites for catalyzing polysulfide conversion and polysulfide trapping. Thus, a Li-S battery with the EuO/KB modified separator delivers highly stable cycling performance and excellent rate capability, with the capacity decay ratio of merely 0.05% per cycle under 1 C rate during 500 cycles, and high specific capacity of 563 mAh g at 3 C rate. This work offers a meaningful exploration of the application of rare earth oxides for the modification of the separator towards high performance Li-S batteries.
锂硫（Li-S）电池因其低成本和超高理论能量密度的显著优势，成为未来最具潜力的动力电池之一。然而，多硫化物的穿梭效应以及这些物质缓慢的氧化还原动力学长期困扰着Li-S电池的商业应用。在此，我们设计了一种由氧化铕掺杂的多孔科琴黑（EuO/KB）包覆的新型电池隔膜，并首次测试了其在Li-S电池中的性能。实验结果和理论计算表明，电化学性能的提升可归因于EuO的存在。EuO与多硫化物之间的强结合作用体现在两个方面：（1）作为路易斯酸的EuO与具有强路易斯碱性的多硫化物之间存在强相互作用；（2）具有氧空位缺陷的EuO为催化多硫化物转化和捕获多硫化物提供了活性位点。因此，采用EuO/KB改性隔膜的Li-S电池具有高度稳定的循环性能和优异的倍率性能，在1 C倍率下500次循环期间容量衰减率仅为每循环0.05%，在3 C倍率下具有563 mAh g的高比容量。这项工作为稀土氧化物在高性能Li-S电池隔膜改性方面的应用提供了有意义的探索。
