MoS 2 /graphene nanocomposite with enlarged interlayer distance as a high performance anode material for lithium-ion bat
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Yang Gao, Zheng Jiao, Lingli Cheng, and Bing Zhaob) Shanghai Applied Radiation Institute, Shanghai University, Shanghai 201800, People’s Republic of China (Received 18 July 2016; accepted 26 August 2016)
In this article, we report on the preparation of few-layered MoS2/graphene nanocomposite (MoS2/GNS-G) with enlarged interlayer distance as the lithium-ion battery anode via a facile hydrothermal method followed by glucose-assisted thermal annealing. During the synthesis, glucose serving as a small organic molecule can interlay into MoS2 nanosheets, which effectively hinder the aggregation and restacking of MoS2 during the process of heat treatment, retaining a sandwich structure of the composite. The enlarged interlayer distance (approximately 0.98 nm), along with the inserted amorphous carbon, could promote efficient lithium migration into active sites, buffer the volume change and stabilize the electrode structure effectively during the lithium insertion/extraction cycling. Electrochemical tests demonstrate that the MoS2/GNS-G delivers a high discharge capacity of 1583.0 mA h/g in the initial cycle at current density of 100 mA/g. The specific capacity remained at the relative high value of 673.5 mA h/g even at a current density of 1000 mA/g.
I. INTRODUCTION
Since the 21st century, environmental pollution and energy shortage problems have become an increasingly serious issue. There is an urgent need for the development and utilization of various clean and economical power sources. Currently commercial graphite anode material, with the theoretical lithium storage capacity of only 372 mA h/g, has been unable to meet the growing requirements of high energy density batteries. Therefore, the new generation of battery materials with high capacity and long cycle stability is the focus and the direction of the research. Although the theoretical capacity of graphene sheets is low, it has also attracted great scientific interest recently for lithium ion batteries due to its versatile combination of outstanding electronic conductivity, high charge mobility, large specific surface area, and good flexibility. Graphite-like transition metal disulfide MoS2 and graphene posses many superior physical and chemical characterizations. Owning to their matching crystal structure and micro-morphology, as well as their complementary electrical properties, these materials are becoming a hot spot of current research. The crystal structure of MoS2 is that hexagonal layers of Mo Contributing Editor: Xiaobo Chen Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2016.332
are sandwiched between two S layers. Strong covalent bonding characterizes the Mo–S interactions, while the interactions between S layers are characterized by weak van der Waals interactions.1,2 These weak van der Waals interactions between the sheets indicate that MoS2 can be exfoliated to single-layer or few-layer sheets. It is known to all that the transition metal disulfide nanosheets with single-layer or f
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