Qiu Weilong, Li Gaoran, Luo Dan, Zhang Yongguang, Zhao Yan, Zhou Guofu, Shui Lingling, Wang Xin, Chen Zhongwei
School of Materials Science and Engineering Hebei University of Technology Tianjin 300130 China.
School of Information and Optoelectronic Science and Engineering International Academy of Optoelectronics at Zhaoqing South China Normal University Guangdong 510006 China.
Adv Sci (Weinh). 2021 Jan 29;8(7):2003400. doi: 10.1002/advs.202003400. eCollection 2021 Apr.
Rational construction of sulfur electrodes is essential in pursuit of practically viable lithium-sulfur (Li-S) batteries. Herein, bimetallic NiCo-layered double hydroxide (NiCo-LDH) with a unique hierarchical micro-nano architecture is developed as an advanced sulfur reservoir for Li-S batteries. Compared with the monometallic Co-layered double hydroxide (Co-LDH) counterpart, the bimetallic configuration realizes much enriched, miniaturized, and vertically aligned LDH nanosheets assembled in hollow polyhedral nanoarchitecture, which geometrically benefits the interface exposure for host-guest interactions. Beyond that, the introduction of secondary metal intensifies the chemical interactions between layered double hydroxide (LDH) and sulfur species, which implements strong sulfur immobilization and catalyzation for rapid and durable sulfur electrochemistry. Furthermore, the favorable NiCo-LDH is architecturally upgraded into closely packed micro-nano clusters with facilitated long-range electron/ion conduction and robust structural integrity. Due to these attributes, the corresponding Li-S cells realize excellent cyclability over 800 cycles with a minimum capacity fading of 0.04% per cycle and good rate capability up to 2 C. Moreover, highly reversible areal capacity of 4.3 mAh cm can be achieved under a raised sulfur loading of 5.5 mg cm. This work provides not only an effective architectural design but also a deepened understanding on bimetallic LDH sulfur reservoir for high-performance Li-S batteries.
合理构建硫电极对于实现切实可行的锂硫（Li-S）电池至关重要。在此，具有独特分级微纳结构的双金属镍钴层状双氢氧化物（NiCo-LDH）被开发为用于Li-S电池的先进硫储存器。与单金属钴层状双氢氧化物（Co-LDH）相比，双金属结构实现了在中空多面体纳米结构中组装的更丰富、更小尺寸且垂直排列的LDH纳米片，这在几何上有利于主客体相互作用的界面暴露。除此之外，引入的第二种金属增强了层状双氢氧化物（LDH）与硫物种之间的化学相互作用，实现了对硫的强固定和催化，以实现快速且持久的硫电化学。此外，优良的NiCo-LDH在结构上升级为紧密堆积的微纳簇，具有便利的长程电子/离子传导和稳健的结构完整性。由于这些特性，相应的Li-S电池在800次循环中实现了优异的循环稳定性，每次循环的最小容量衰减为0.04%，并且在高达2 C的倍率下具有良好的倍率性能。此外，在5.5 mg cm的硫负载量增加的情况下，可以实现4.3 mAh cm的高可逆面积容量。这项工作不仅提供了一种有效的结构设计，还加深了对用于高性能Li-S电池的双金属LDH硫储存器的理解。
