Coal-Derived Graphene/MoS₂ Heterostructure Electrodes for Li-Ion Batteries: Experiment and Simulation Study

Abstract

A novel coal-derived graphene-intercalated MoS 2 heterostructure was prepared with a facile in situ hydrothermal approach followed by high-temperature calcination. XRD, FE-SEM, HR-TEM, HR-Raman, and TOC analytical instruments, combined with first-principles simulations, were employed to explore the structural and electrochemical properties of this heterostructure for use as an electrode material. The XRD measurements and simulations confirmed the formation of the MoS 2 /graphene (MoS 2 -G) heterostructure. The microstructure analysis indicated that a well-defined 3D flower-like structure with tunable interlayer distances was created in the MoS 2 layer. The novel MoS 2 -09% G anode exhibits a remarkable initial discharge capacity of ∼929 mAh/g due to its interlayer expansion from the intercalation of graphene between the MoS 2 layers. This anode maintains a capacity of ∼813 mAh/g with a Coulombic efficiency (CE) of ∼99% after 150 cycles at a constant current density of 100 mA/g. This anode also delivers a high-rate capability of ∼579 mAh/g at a current density of 2000 mA/g, significantly higher than that of other comparable structures. The unique flower-like arrangement, sufficient interlayer spacing for Li-ion diffusion, and the increased conductive matrix created using coal-derived graphene enhance the electrode kinetics during electrochemical reactions. Our firstprinciples calculations revealed that the diffusion barriers are significantly lower in heterostructures compared to that of bare MoS 2 . This heterostructure design has significant potential as a new type of anode for Li-ion storage in next-generation batteries.

Experimental Realization and Computational Investigations of B2S2 as a New 2D Material with Potential Applications

“…Electrons on the top of S atoms are also highly localized, besides those in the covalent bonds, which is proof of the existence of lone pair electrons in S atoms as well. This electron-sufficient sp 3 hybridized structure of T-B 2 S 2 grants better stability and feasibility of free-standing nanosheet synthesis than many other two-dimensional boron-based materials, for instance, borophene with electron-deficient 3c-2e bonds, which can only be synthesized upon Ag or other substrates of the sort.…”

“…The discovery of graphene sparked a research upsurge in two-dimensional materials, as they show unprecedented properties, including but not limited to electronic, optical, mechanical, and other aspects, which is mainly due to the presence of electron–electron coupling and quantum confinement effects . Theoretical and experimental investigations into a growing variety of two-dimensional materials have hitherto promoted their applications, such as energy storage, optoelectronic devices, and catalysis . Among various types of two-dimensional materials, transition-metal dichalcogenides (TMDs) have greatly captured the interests of researchers.…”

Interlayer-Expanded MoS2 Nanoflowers Vertically Aligned on MXene@Dual-Phased TiO2 as High-Performance Anode for Sodium-Ion Batteries

“…MoS 2 as a member of layer transition metal dichalcogenides is a promising candidate with adjustable band gaps, large interlayer distance, ambient stability, facile synthesis, and natural availability. Many investigations have been made in developing MoS 2 based electrode materials due to its typical analogue to graphite layered materials, providing a high sodium storage capacity (theoretical capacities of 670 mA h g –1 ) for SIBs. − S–Mo–S three-atom layer bonded by weak van der Waals force in exfoliated MoS 2 possesses an interlayer distance that could reach 0.62 nm which is much larger than the radius of the Na + (1.02 Å). Nonetheless, MoS 2 always suffers from capacity decays during cycling and low electronic conductivity owing to the huge volume change and inevitable aggregation plus the deformation of 2D layers .…”

Single- and Multilayers of Alkali Metal Atoms inside Graphene/MoS2 Heterostructures: A Systematic First-Principles Study

“…The intercalation of alkali metal (AM) atoms into layered bulk and low-dimensional materials has recently received an enormous amount of attention in the context of energy storage − and tuning the opto-electronic properties of the materials. − As for the former, increasing the capacity of metal-ion batteries is believed to be crucial for further development of portable electronics and electrical vehicles. One of the promising directions of improving the characteristics of metal-ion batteries, such as the capacity and the critical number of cycles, is the use of composites as anodes. − Among these systems, van der Waals (vdW) heterostructures consisting of stacked layers of graphene and transition metal dichalcogenides (TMDs), such as MoS 2 , have attracted particular attention − as perspective metal anode materials. MoS 2 has low electronic conductivity and undergoes a strong volume change upon intercalation/deintercalation, but intercalation of AMs into these systems is energetically more favorable as compared to graphitic structures, so that a combination of MoS 2 with conductive carbon matrices is expected to be a promising direction.…”

“…MoS 2 has low electronic conductivity and undergoes a strong volume change upon intercalation/deintercalation, but intercalation of AMs into these systems is energetically more favorable as compared to graphitic structures, so that a combination of MoS 2 with conductive carbon matrices is expected to be a promising direction. In particular, MoS 2 /graphene heterostructures were synthesized − and demonstrated to be promising systems as anode materials in lithium-ion batteries exhibiting extraordinary capacity (up to 1300 mA h g –1 ) and excellent rate capability and cycling stability.…”