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Journal ArticleDOI

Freestanding Metallic 1T MoS2 with Dual Ion Diffusion Paths as High Rate Anode for Sodium-Ion Batteries

01 Oct 2017-Advanced Functional Materials (John Wiley & Sons, Ltd)-Vol. 27, Iss: 40, pp 1702998
TL;DR: In this article, the metallic 1T MoS2 sandwich grown on graphene tube was used as a freestanding intercalation anode for promising sodium-ion batteries (SIBs).
Abstract: This work studies for the first time the metallic 1T MoS2 sandwich grown on graphene tube as a freestanding intercalation anode for promising sodium-ion batteries (SIBs). Sodium is earth-abundant and readily accessible. Compared to lithium, the main challenge of sodium-ion batteries is its sluggish ion diffusion kinetic. The freestanding, porous, hollow structure of the electrode allows maximum electrolyte accessibility to benefit the transportation of Na+ ions. Meanwhile, the metallic MoS2 provides excellent electron conductivity. The obtained 1T MoS2 electrode exhibits excellent electrochemical performance: a high reversible capacity of 313 mAh g−1 at a current density of 0.05 A g−1 after 200 cycles and a high rate capability of 175 mAh g−1 at 2 A g−1. The underlying mechanism of high rate performance of 1T MoS2 for SIBs is the high electrical conductivity and excellent ion accessibility. This study sheds light on using the 1T MoS2 as a novel anode for SIBs.
Citations
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Journal ArticleDOI
TL;DR: In this article, a 3DG/TM heterostructure for Li-S batteries is proposed to suppress the polysulfide shuttle in Li−S batteries by designing a freestanding, three-dimensional graphene/1T MoS2 (3DG-MoS2) heterostructures with highly efficient electrocatalysis properties for LiPSs.
Abstract: A novel approach to effectively suppress the “polysulfide shuttle” in Li–S batteries is presented by designing a freestanding, three-dimensional graphene/1T MoS2 (3DG/TM) heterostructure with highly efficient electrocatalysis properties for lithium polysulfides (LiPSs). The 3DG/TM heterostructure is constructed by few-layered graphene nanosheets sandwiched by hydrophilic, metallic, few-layered 1T MoS2 nanosheets with abundant active sites. The porous 3D structure and the hydrophilic feature of 1T-MoS2 are beneficial for electrolyte penetration and Li-ion transfer, and the high conductivities of both graphene and the 1T MoS2 nanosheets facilitate electron transfer. These merits lead to a high electrocatalytic efficiency for LiPSs due to excellent ion/electron transfer and the presence of sufficient electrocatalytic active sites. Therefore, the cells with 3DG/TM exhibit outstanding electrochemical performance, with a high reversible discharge capacity of 1181 mA h g−1 and a capacity retention of 96.3% after 200 cycles. The electrocatalysis mechanism of LiPSs is further experimentally and theoretically revealed, which provides new insights and opportunities to develop advanced Li–S batteries with highly efficient electrocatalysts for LiPS conversion.

455 citations

Journal ArticleDOI
TL;DR: The strategy developed in this work can be generally applied for enhancing the ion storage capacity of metal chalcogenides and other layered materials, making them promising cathodes for challenging multivalent ion batteries.
Abstract: Aqueous Zn-ion batteries present low-cost, safe, and high-energy battery technology but suffer from the lack of suitable cathode materials because of the sluggish intercalation kinetics associated with the large size of hydrated zinc ions. Herein we report an effective and general strategy to transform inactive intercalation hosts into efficient Zn2+ storage materials through intercalation energy tuning. Using MoS2 as a model system, we show both experimentally and theoretically that even hosts with an originally poor Zn2+ diffusivity can allow fast Zn2+ diffusion. Through simple interlayer spacing and hydrophilicity engineering that can be experimentally achieved by oxygen incorporation, the Zn2+ diffusivity is boosted by 3 orders of magnitude, effectively enabling the otherwise barely active MoS2 to achieve a high capacity of 232 mAh g–1, which is 10 times that of its pristine form. The strategy developed in our work can be generally applied for enhancing the ion storage capacity of metal chalcogenides ...

316 citations

Journal ArticleDOI
04 Mar 2020
TL;DR: In this paper, transition metal dichalcogenides (TMDs) are evaluated for performance in electrocatalytic conversion (hydrogen evolution reaction) and electrochemical energy storage systems (NiB/LiB/supercapacitors).
Abstract: Summary Transition metal dichalcogenides (TMDs) are promising materials for use in electrocatalytic and electrochemical energy-storage systems owing to their exceptional physicochemical properties, including large surface area, remarkable mechanical properties, high catalytic activity, chemical stability, and low cost. In further improving material properties tailored to meet application-specific requirements, heterostructure construction holds significant advantages, benefiting from the synergistic effect between constituents involved. TMD-based heterostructures have been widely explored recently, giving rise to diverse materials with desirable characteristics such as significantly increased interfacial contact of low resistance for efficient electron transfers, constituent-dependent electronic structure, tunable layer distances facilitating easily intercalation of redox species, and increased surface area for effective interaction with electrolyte. In this review, TMD-based heterostructures are assessed for performance in electrocatalytic conversion (hydrogen evolution reaction) and electrochemical energy-storage systems (NiB/LiB/supercapacitors). The impactful strategies employed in overcoming key challenges are evaluated, and finally, future directions for TMD-based heterostructure construction are presented.

283 citations

References
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Journal ArticleDOI
TL;DR: Above an annealing temperature of 300 °C, chemically exfoliated MoS2 exhibit prominent band gap photoluminescence, similar to mechanically exfoliate monolayers, indicating that their semiconducting properties are largely restored.
Abstract: A two-dimensional crystal of molybdenum disulfide (MoS2) monolayer is a photoluminescent direct gap semiconductor in striking contrast to its bulk counterpart. Exfoliation of bulk MoS2 via Li intercalation is an attractive route to large-scale synthesis of monolayer crystals. However, this method results in loss of pristine semiconducting properties of MoS2 due to structural changes that occur during Li intercalation. Here, we report structural and electronic properties of chemically exfoliated MoS2. The metastable metallic phase that emerges from Li intercalation was found to dominate the properties of as-exfoliated material, but mild annealing leads to gradual restoration of the semiconducting phase. Above an annealing temperature of 300 °C, chemically exfoliated MoS2 exhibit prominent band gap photoluminescence, similar to mechanically exfoliated monolayers, indicating that their semiconducting properties are largely restored.

3,403 citations

Journal ArticleDOI
TL;DR: Structural characterization and electrochemical studies confirmed that the nanosheets of the metallic MoS2 polymorph exhibit facile electrode kinetics and low-loss electrical transport and possess a proliferated density of catalytic active sites, which make these metallic nanOSheets a highly competitive earth-abundant HER catalyst.
Abstract: Promising catalytic activity from molybdenum disulfide (MoS2) in the hydrogen evolution reaction (HER) is attributed to active sites located along the edges of its two-dimensional layered crystal structure, but its performance is currently limited by the density and reactivity of active sites, poor electrical transport, and inefficient electrical contact to the catalyst. Here we report dramatically enhanced HER catalysis (an electrocatalytic current density of 10 mA/cm2 at a low overpotential of −187 mV vs RHE and a Tafel slope of 43 mV/decade) from metallic nanosheets of 1T-MoS2 chemically exfoliated via lithium intercalation from semiconducting 2H-MoS2 nanostructures grown directly on graphite. Structural characterization and electrochemical studies confirmed that the nanosheets of the metallic MoS2 polymorph exhibit facile electrode kinetics and low-loss electrical transport and possess a proliferated density of catalytic active sites. These distinct and previously unexploited features of 1T-MoS2 make ...

2,899 citations

Journal ArticleDOI
TL;DR: It is shown that chemically exfoliated nanosheets of MoS2 containing a high concentration of the metallic 1T phase can electrochemically intercalate ions with extraordinary efficiency and achieve capacitance values ranging from ∼400 to ∼700 F cm(-3) in a variety of aqueous electrolytes.
Abstract: The 1T metallic phase of MoS2 shows high volumetric capacitance and electrochemical properties that are attractive for supercapacitor applications. Efficient intercalation of ions in layered materials forms the basis of electrochemical energy storage devices such as batteries and capacitors1,2,3,4,5,6. Recent research has focused on the exfoliation of layered materials and then restacking the two-dimensional exfoliated nanosheets to form electrodes with enhanced electrochemical response7,8,9,10,11. Here, we show that chemically exfoliated nanosheets of MoS2 containing a high concentration of the metallic 1T phase can electrochemically intercalate ions such as H+, Li+, Na+ and K+ with extraordinary efficiency and achieve capacitance values ranging from ∼400 to ∼700 F cm−3 in a variety of aqueous electrolytes. We also demonstrate that this material is suitable for high-voltage (3.5 V) operation in non-aqueous organic electrolytes, showing prime volumetric energy and power density values, coulombic efficiencies in excess of 95%, and stability over 5,000 cycles. As we show by X-ray diffraction analysis, these favourable electrochemical properties of 1T MoS2 layers are mainly a result of their hydrophilicity and high electrical conductivity, as well as the ability of the exfoliated layers to dynamically expand and intercalate the various ions.

2,154 citations

Journal ArticleDOI
20 May 2011-ACS Nano
TL;DR: The superior electrochemical performances of MoS(2)/G composites as Li-ion battery anodes are attributed to their robust composite structure and the synergistic effects between layered MoS (2) and graphene.
Abstract: A facile process was developed to synthesize layered MoS2/graphene (MoS2/G) composites by an l-cysteine-assisted solution-phase method, in which sodium molybdate, as-prepared graphene oxide (GO), and l-cysteine were used as starting materials. As-prepared MoS2/G was then fabricated into layered MoS2/G composites after annealing in a H2/N2 atmosphere at 800 °C for 2 h. The samples were systematically investigated by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy. Electrochemical performances were evaluated in two-electrode cells versus metallic lithium. It is demonstrated that the obtained MoS2/G composites show three-dimensional architecture and excellent electrochemical performances as anode materials for Li-ion batteries. The MoS2/G composite with a Mo:C molar ratio of 1:2 exhibits the highest specific capacity of ∼1100 mAh/g at a current of 100 mA/g, as well as excellent cycling stability and hig...

1,516 citations

Journal ArticleDOI
27 Jan 2014-ACS Nano
TL;DR: The synthesis and electrochemical and mechanical performance of layered free-standing papers composed of acid-exfoliated few-layer molybdenum disulfide and reduced graphene oxide flakes for use as a self-standing flexible electrode in sodium-ion batteries are studied.
Abstract: We study the synthesis and electrochemical and mechanical performance of layered free-standing papers composed of acid-exfoliated few-layer molybdenum disulfide (MoS2) and reduced graphene oxide (rGO) flakes for use as a self-standing flexible electrode in sodium-ion batteries. Synthesis was achieved through vacuum filtration of homogeneous dispersions consisting of varying weight percent of acid-treated MoS2 flakes in GO in DI water, followed by thermal reduction at elevated temperatures. The electrochemical performance of the crumpled composite paper (at 4 mg cm–2) was evaluated as counter electrode against pure Na foil in a half-cell configuration. The electrode showed good Na cycling ability with a stable charge capacity of approximately 230 mAh g–1 with respect to total weight of the electrode with Coulombic efficiency reaching approximately 99%. In addition, static uniaxial tensile tests performed on crumpled composite papers showed high average strain to failure reaching approximately 2%.

1,080 citations