Sandwich‐Like Heterostructures of MoS2/Graphene with Enlarged Interlayer Spacing and Enhanced Hydrophilicity as High‐Performance Cathodes for Aqueous Zinc‐Ion Batteries

• Published in: Advanced materials (Weinheim) Vol. 33; no. 12; pp. e2007480 - n/a
• Main Authors: Li, Shengwei, Liu, Yongchang, Zhao, Xudong, Shen, Qiuyu, Zhao, Wang, Tan, Qiwei, Zhang, Ning, Li, Ping, Jiao, Lifang, Qu, Xuanhui
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.03.2021
• Subjects: aqueous zinc‐ion batteries; cathode materials; Cathodes; Density functional theory; Energy storage; Graphene; Heterostructures; Hydrophilicity; Interlayers; Ion diffusion; Layered materials; Materials science; Molybdenum disulfide; Nanocomposites; Phase transitions; reaction mechanisms; Structural stability; Two dimensional materials; Zinc
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202007480

Layered materials have great potential as cathodes for aqueous zinc‐ion batteries (AZIBs) because of their facile 2D Zn2+ 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 MoS2 gallery, which results in significantly enlarged MoS2 interlayers (from 0.62 to 1.16 nm) and enhanced hydrophilicity. The sandwich‐structured MoS2/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 MoS2/graphene nanocomposite exhibits exceptional high‐rate capability (285.4 mA h g−1 at 0.05 A g−1 with 141.6 mA h g−1 at 5 A g−1) and long‐term cycling stability (88.2% capacity retention after 1800 cycles). The superior Zn2+ 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‐MoS2 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 MoS2/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. A novel sandwich‐like heterostructure of intercalating graphene into a MoS2 gallery significantly enlarges the MoS2 interlayer spacing from 0.62 to 1.16 nm and simultaneously enhances the hydrophilicity. These structural merits enable facilitated Zn‐ion diffusion kinetics and a highly reversible phase transition between 2H‐ and 1T‐MoS2 upon Zn2+ insertion/extraction, thus rendering a splendid high‐rate capability and long‐term cycling stability in aqueous Zn‐ion batteries.