Guan Hui, Dong Yutao, Kang Xiyang, Han Yumiao, Cheng Zihao, Han Lifeng, Xie Lixia, Chen Weihua, Zhang Jianmin
Center of Catalysis, College of Chemistry, Zhengzhou University, Henan, Zhengzhou 450001, China.
College of Science, Henan Agricultural University, Henan, Zhengzhou 450002, China.
J Colloid Interface Sci. 2022 Nov 15;626:374-383. doi: 10.1016/j.jcis.2022.06.148. Epub 2022 Jun 28.
There are many challenges such as the shuttling effect of soluble lithium polysulfides species (LiPSs) and the slow solid-state conversion between LiS and LiS in the development process of lithium-sulfur battery (LSB), so it is vital how to design and fabricate sulfur hosts with strong adsorption and good electrocatalysis. In this work, BiOBr in-situ forms onto both sides of reduced graphene oxide (rGO) to obtain a novel ultrathin BiOBr/rGO sheet, then self-constructing a hydrogel cylinder in shape, via a one-step hydrothermal process. The BiOBr/rGO composite with sandwich structure not only shows the outstanding adsorption effect on LiPSs, resulting from a strong bonding interaction between BiOBr/rGO and LiS demonstrated by XPS technique, but also exhibits the extraordinary electrocatalytic performance on both the LiPSs conversion reaction in cyclic voltammetry experiment of symmetric cell and the LiS nucleation process in potentiostatic deposited experiment, which will significantly improve the electrochemical performance of LSB. The S@BiOBr/rGO electrodes deliver the superior capacity and long cyclic stability with 882.2 mA h g at 0.5 C after 1000 cycles, as well as displays the excellent rate performance with 823.9, 692.6 and 554.2 mA h g at 1 C, 3 C and 5 C, respectively, after 400 cycles. Even though the sulfur loading reaches 4.9 mg cm, the reversible specific capacity of 424.6 mA h gcan be maintained at 0.5 C after 400 cycles. Based on the in-situ X-ray diffraction and in-situ Raman spectroscopy, it could be revealed that the initial discharge process of active sulfur on the BiOBr/rGO cathode is α-S → LiS → LiS → LiS → LiS → LiS, while the charging progress is the corresponding reverse reaction, but the final substance is β-S. This research not only shows that the two-dimensional ultrathin BiOBr/rGO hybrid is successfully developed in LSB with excellent electrochemical performances, but also provides a strategy for exploring the construction of sulfur host materials.
在锂硫电池（LSB）的发展过程中存在许多挑战，例如可溶性多硫化锂物种（LiPSs）的穿梭效应以及LiS和LiS之间缓慢的固态转化，因此如何设计和制造具有强吸附性和良好电催化性能的硫宿主至关重要。在这项工作中，BiOBr原位形成在还原氧化石墨烯（rGO）的两侧，以获得一种新型超薄BiOBr/rGO片材，然后通过一步水热法自组装成圆柱形水凝胶。具有三明治结构的BiOBr/rGO复合材料不仅对LiPSs表现出出色的吸附效果，这是通过XPS技术证明的BiOBr/rGO与LiS之间的强键相互作用导致的，而且在对称电池的循环伏安实验中的LiPSs转化反应以及恒电位沉积实验中的LiS成核过程中均表现出非凡的电催化性能，这将显著提高LSB的电化学性能。S@BiOBr/rGO电极在1000次循环后，在0.5 C下具有882.2 mA h g的优异容量和长循环稳定性，并且在400次循环后，在1 C, 3 C和5 C下分别具有823.9、692.6和554.2 mA h g的出色倍率性能。即使硫负载量达到4.9 mg cm，在400次循环后，在0.5 C下仍可保持424.6 mA h g的可逆比容量。基于原位X射线衍射和原位拉曼光谱，可以揭示BiOBr/rGO阴极上活性硫的初始放电过程为α-S→LiS→LiS→LiS→LiS→LiS，而充电过程是相应的逆反应，但最终产物是β-S。这项研究不仅表明二维超薄BiOBr/rGO杂化物在LSB中成功开发并具有优异的电化学性能，而且为探索硫宿主材料的构建提供了一种策略。
