Li Shengwei, Liu Yongchang, Zhao Xudong, Shen Qiuyu, Zhao Wang, Tan Qiwei, Zhang Ning, Li Ping, Jiao Lifang, Qu Xuanhui
Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing, 100083, China.
College of Chemistry and Environmental Science, Hebei University, Baoding, 071002, China.
Adv Mater. 2021 Mar;33(12):e2007480. doi: 10.1002/adma.202007480. Epub 2021 Feb 17.
Layered materials have great potential as cathodes for aqueous zinc-ion batteries (AZIBs) because of their facile 2D Zn transport channels; however, either low capacity or poor cycling stability limits their practical applications. Herein, two classical layered materials are innovatively combined by intercalating graphene into MoS gallery, which results in significantly enlarged MoS interlayers (from 0.62 to 1.16 nm) and enhanced hydrophilicity. The sandwich-structured MoS /graphene nanosheets self-assemble into a flower-like architecture that facilitates Zn-ion diffusion, promotes electrolyte infiltration, and ensures high structural stability. Therefore, this novel MoS /graphene nanocomposite exhibits exceptional high-rate capability (285.4 mA h g at 0.05 A g with 141.6 mA h g at 5 A g ) and long-term cycling stability (88.2% capacity retention after 1800 cycles). The superior Zn migration kinetics and desirable pseudocapacitive behaviors are confirmed by electrochemical measurements and density functional theory computations. The energy storage mechanism regarding the highly reversible phase transition between 2H- and 1T-MoS upon Zn-ion insertion/extraction is elucidated through ex situ investigations. As a proof of concept, a flexible quasi-solid-state zinc-ion battery employing the MoS /graphene cathode demonstrates great stability under different bending conditions. This study paves a new direction for the design and on-going development of 2D materials as high-performance cathodes for AZIBs.
层状材料因其具有便捷的二维锌离子传输通道，作为水系锌离子电池（AZIBs）的阴极具有巨大潜力；然而，低容量或差的循环稳定性限制了它们的实际应用。在此，通过将石墨烯插入到MoS层间，创新性地将两种经典层状材料结合在一起，这导致MoS层间显著扩大（从0.62纳米增大到1.16纳米）并增强了亲水性。三明治结构的MoS /石墨烯纳米片自组装成花状结构，有利于锌离子扩散，促进电解质渗透，并确保高结构稳定性。因此，这种新型MoS /石墨烯纳米复合材料表现出优异的高倍率性能（在0.05 A g时为285.4 mA h g，在5 A g时为141.6 mA h g）和长期循环稳定性（1800次循环后容量保持率为88.2%）。电化学测量和密度泛函理论计算证实了优异的锌迁移动力学和理想的赝电容行为。通过非原位研究阐明了锌离子插入/脱出时2H-和1T-MoS之间高度可逆相变的储能机制。作为概念验证，采用MoS /石墨烯阴极的柔性准固态锌离子电池在不同弯曲条件下表现出极大的稳定性。这项研究为二维材料作为AZIBs高性能阴极的设计和持续发展开辟了新方向。
