In Situ Assembly of 2D Conductive Vanadium Disulfide with Graphene as a High‐Sulfur‐Loading Host for Lithium–Sulfur Batteries

Abstract

The ever-growing demand for high-energy and long-life energy storage devices has spurred extensive research beyond conventional lithium-ion battery systems. Amongst these, rechargeable lithium-sulfur (Li-S) batteries, as a promising next-generation energy storage technology, have captured vast interest because of the high capacity (1672 mAh g −1 ), large abundance of sulfur, and environmental compatibility. [1][2][3][4] Although there has been significant advance by far in designing state-of-theart Li-S batteries, their practical utilization and large-scale commercialization are still impeded by a multitude of technological obstacles, namely, i) the insulating nature of S/Li 2 S that would jeopardize the overall conductivity of the electrode and hence affect the utilization of sulfur; ii) the shuttle effect induced by the dissolution and diffusion of lithium polysulfide that could lead to a rapid capacity fading; and iii) the considerable volume expansion of the sulfur cathode upon cycling. [5,6] To tackle these issues, great efforts have been devoted to developing appropriate host materials in combination with optimizing the cathode architectures toward advanced Li-S batteries. A ubiquitously employed strategy is to encapsulate sulfur and/or polysulfides with the aid of porous carbonaceous materials, such as carbon nanotubes, [1,[7][8][9][10] hollow carbon spheres, [11,12] and graphene, [13][14][15] aiming to attain enhanced electrode conductivity, improved sulfur utilization, and buffered volume change. However, this has been proved to be far from ideal, owing to weak van der Waals (vdW) interaction between nonpolar carbon and polar polysulfide species that only gives rise to a physical confinement, insufficient to alleviate the polysulfide shuttle over a long lifespan. In this regard, the introduction of polar nanomaterials (e.g., transition metal oxides, [16][17][18] sulfides, [19][20][21] and nitrides [22,23] ) within the sulfur host has witnessed an efficient suppression of shuttle effect, where polysulfides are chemically anchored onto these polar species. Nevertheless, the limited electrical conductivity of most metal oxides/sulfides would otherwise result in sluggish kinetics of polysulfide redox reactions, inevitably causing poor rate capability and fast capacity decay. Latest investigations have revealed that the integration of polar nanocrystals/nanosheets Lithium-sulfur (Li-S) batteries are deemed to be one of the most promising energy storage technologies because of their high energy density, low cost, and environmental benignancy. However, existing drawbacks including the shuttling of intermediate polysulfides, the insulating nature of sulfur, and the considerable volume change of sulfur cathode would otherwise result in the capacity fading and unstable cycling. To overcome these challenges, herein an in situ assembly route is presented to fabricate VS 2 /reduced graphene oxide nanosheets (G-VS 2 ) as a sulfur host. Benefiting from the 2D conductive and polar VS 2 interlayered within a graphene fra...

High‐Sulfur‐Content Graphene‐Based Composite through Ethanol Evaporation for High‐Energy Lithium‐Sulfur Battery

“…The sulfur-FLGs agglomerates have size of approximately 20 mm, in agreement with the value of the startingm aterial, as shown in the SEM images of Figure 4. Additionally,t he FLG matrix adopted in the electrode is not limited to lab-scale production.Moreover,the use of ethanol reflects the environmental compatibilityo ft he synthesis, confirmingt he suitability of this approach for scalingu p. To this end, future investigation should be devotedt of urther increasingt he energyd ensity and stabilityo ft he final device by tuning the electrode properties in terms of sulfur mass loading [27,38,75,76] and active material morphology, and optimizing the cell configurationt hrough innovative approaches such as the use of carbon interlayer separators, [36,77] exploitingt he polysulfide retentione ffect of transition metal oxide on the carbonaceouss urface, [78][79][80][81] and electrolyte optimization using polysulfide mixtures. [82]…”

2D Metallic Transitional Metal Dichalcogenides for Electrochemical Hydrogen Evolution

“…Recently, this method has also been applied to synthesize MTMDC nanosheets (e.g., VS 2 , VSe 2 , etc.) and the related heterostructures (e.g., VS 2 /reduced graphene oxide [rGO] hybrids, etc.). A summary of the colloidal synthesis methods of 2D MTMDCs is presented in Table .…”

Insight into the Anchoring and Catalytic Effects of VO2 and VS2 Nanosheets as Sulfur Cathode Hosts for Li–S Batteries

“…The negative physiochemical properties of Li 2 S n , including low electronic conductivity, poor Li + diffusivity, high dissolvability, and large decomposition energy, seriously hinder the electrochemical performance of Li–S batteries. To address these problems, many transition‐metal oxides and their sulfide counterparts have been studied as HMs for Li–S batteries. However, very little is known regarding the distinctions between them in Li–S battery operations.…”

“…ic ability of these HMs can decrease the decomposition energy of Li 2 S, resulting in fast reactionkinetics. [11] In Li-S batteries, the Sc athode experiences multiple reduction/oxidation reaction steps duringc ycling, consequently forming as eries of Li 2 S n intermediate products.T he negative physiochemical properties of Li 2 S n ,i ncluding low electronic conductivity,p oor Li + diffusivity,h igh dissolvability,a nd large decomposition energy,s eriously hinder the electrochemical performance of Li-S batteries.T oa ddress these problems, many transition-metal oxides [13,45] and their sulfide counterparts [46][47][48] have been studied as HMsf or Li-S batteries. However,v ery little is known regarding the distinctions between them in Li-S battery operations.…”