Adsorption of insoluble polysulfides Li2Sx (x = 1, 2) on Li2S surfaces

Liu, Zhixiao; Hubble, Dion; Balbuena, Perla B.; Mukherjee, Partha P.

doi:10.1039/c4cp06118g

Cited by 57 publications

(50 citation statements)

References 43 publications

(48 reference statements)

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“…In our earlier work, it was determined that the Li 2 S adsorption energy on the Li 2 S (111) surface is −1.78 eV without the vdW dispersion correction. 50 However stronger adsorption values of −2.25 eV and −2.40 eV are obtained with the vdW-D3 27 and vdW(BJ) 28 approaches, respectively.…”

Section: Electrochemical Performance Of Ccs/s Composite Vs Lithium-mentioning

confidence: 99%

“…In Structure-I, the Li-S bond length (Table II) is 0.27 Å shorter than the Li-S bond in the Li 2 S crystal. 50 The length of the short S-S bridge (D S−S ) in Structure-I is 0.35 Å shorter than the S-S distance (4.05 Å) in a typical Li 2 S (110) layer. The variation of these geometric parameters is attributed to the lattice parameter differences between graphene and the Li 2 S (110) layer.…”

Section: Electrochemical Performance Of Ccs/s Composite Vs Lithium-mentioning

confidence: 99%

“…The adsorbed Li 2 S geometric parameters (Table I) are very similar to those of the molecular adsorption on the Li 2 S (111) surface. 50 Even when the Li-C distance is larger than that of Li atoms adsorbed in graphene, 51 there is an electron transfer from the Li 2 S molecule to the substrate C atoms. This results in a region of electron accumulation at the interface ( Figure 6) and formation of Li-C bonds.…”

Section: Electrochemical Performance Of Ccs/s Composite Vs Lithium-mentioning

confidence: 99%

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Towards Next Generation Lithium-Sulfur Batteries: Non-Conventional Carbon Compartments/Sulfur Electrodes and Multi-Scale Analysis

Dysart

Burgos

Mistry

et al. 2016

J. Electrochem. Soc.

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In this work, a novel heterofunctional, bimodally-porous carbon morphology, termed the carbon compartment (CC), is utilized as a sulfur host within a lithium-sulfur battery cathode. A multi-scale model explores the physics and chemistry of the lithium-sulfur battery cathode. The CCs are synthesized through a rapid, low cost process to improve electrode-electrolyte interfacial contact and accommodate volumetric expansion associated with sulfide formation. The CCs demonstrate controllable sulfur loading and ca. 700 mAh g −1 (at 47%-wt S) reversible capacity with high coulombic efficiency due to their unique structures. Density functional theory and ab initio molecular dynamics characterize the interface between the C/S composite and electrolyte during the sulfur reduction mechanism. Stochastic realizations of 3D electrode microstructures are reconstructed based on representative SEM micrographs to study the influence of solid sulfur loading and lithium sulfide precipitation on microstructural and electrochemical properties. A macroscale electrochemical performance model is developed to analyze the performance of lithium-sulfur batteries. The combined multi-scale simulation studies explain key fundamentals of sulfur reduction and its relation to the polysulfide shuttle mechanism: how the process is affected due to the presence of carbon substrate, thermodynamics of lithium sulfide formation and deposition on carbon, and microstructural effects on the overall cell performance. The goal of developing new and efficient renewable energy technologies from intermittent energy sources, such as solar and wind, necessitates the need for effective, economical, and safe energy storage.1-3 While batteries and supercapacitors have been considered the best options to address this issue, their progress is staggered by both challenging synthesis problems and a continually-developing understanding of their fundamental electrochemistry. 4 Currently, lithiumion batteries dominate the market for portable electronic devices; however, their cost and relatively low energy density prevents them from being used in electrical vehicle applications at this juncture. [4][5][6] Going beyond lithium-ion chemistry, lithium-sulfur and lithium-air are among the most promising battery technologies that can potentially meet the required specific energy target of about 1,000 Wh kg −1 needed to improve the viability of electrical vehicles. 5,7The appeal of a sulfur-based cathode lies in its high theoretical capacity that is about one order of magnitude higher than current metal oxide-based cathodes. Sulfur is also cheaper and more environmentally-friendly than today's commercial cathode materials. 7Low density and natural abundancy in the earth's crust imply that the use of elemental sulfur in the manufacture of lithium-sulfur (Li-S) batteries will be cost effective and demonstrate low environmental impact.8 Thus, Li-S batteries hold significant promise due to their high theoretical specific energy of 2,567 Wh kg −1 , 9 assuming the complete electroche...

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Section: Electrochemical Performance Of Ccs/s Composite Vs Lithium-mentioning

confidence: 99%

Section: Electrochemical Performance Of Ccs/s Composite Vs Lithium-mentioning

confidence: 99%

Section: Electrochemical Performance Of Ccs/s Composite Vs Lithium-mentioning

confidence: 99%

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Towards Next Generation Lithium-Sulfur Batteries: Non-Conventional Carbon Compartments/Sulfur Electrodes and Multi-Scale Analysis

Dysart

Burgos

Mistry

et al. 2016

J. Electrochem. Soc.

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“…1,2 Of particular concern to the loss of capacity with cycling is the deposition of electrochemically-inaccessible solid sulfide species (Li 2 S x , x < 3). 4,5 Multiple literature reports have reached different conclusions on the existence of the solid, electrolyte-insoluble species Li 2 S 2 and whether it forms as a solid intermediate during the discharge of Li-S batteries. [5][6][7][8][9][10][11][12] Recent studies have suggested there may be separate reaction pathways that are followed at different points during Li-S discharge: one where only Li 2 S is formed during reduction of soluble polysulfides (Li 2 S x , x > 2), and a second where both Li 2 S and Li 2 S 2 are formed simultaneously.…”

mentioning

confidence: 99%

“…[5][6][7][8][9][10][11][12] Recent studies have suggested there may be separate reaction pathways that are followed at different points during Li-S discharge: one where only Li 2 S is formed during reduction of soluble polysulfides (Li 2 S x , x > 2), and a second where both Li 2 S and Li 2 S 2 are formed simultaneously. 11 The question of whether any Li 2 S 2 that forms can then be reduced is debated in the literature.…”

mentioning

confidence: 99%

Elucidating the Electrochemical Activity of Electrolyte-Insoluble Polysulfide Species in Lithium-Sulfur Batteries

Klein

Goossens

Bielawski

et al. 2016

J. Electrochem. Soc.

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The direct synthesis of Li 2 S 2 , a proposed solid intermediate in the discharge of lithium-sulfur (Li-S) batteries, was accomplished by treating elemental lithium with sulfur in liquid ammonia at −41 • C. The as-synthesized product was analyzed by X-ray photoelectron spectroscopy (XPS) as well as X-ray diffraction (XRD) and determined to be a mixture of crystalline Li 2 S, amorphous Li 2 S 2, and higher-order polysulfides (Li 2 S x , x > 2). Monitored filtration followed by a tailored electrochemical approach was used to successfully remove the higher-order polysulfides and yielded a powder, which was determined by XPS to be comprised of ∼9 mol% insoluble polysulfide species (mainly Li 2 S 2 ) and ∼91 mol% Li 2 S. This material was discharged galvanostatically in an electrochemical cell and, despite the lack of soluble polysulfide species, was shown to exhibit a discharge plateau at ∼2.1 V vs. Li/Li + . This result confirmed the electrochemical reducibility of electrolyte-insoluble polysulfides in Li-S batteries. Moreover, it was determined that the reduction of solid polysulfides was confined to areas where the sulfur-sulfur bonds were in intimate contact with the conductive current collector. Finally, it was observed that commercially available Li 2 S samples contain significant quantities of polysulfide-type impurities. Lithium-sulfur (Li-S) batteries have emerged in recent years as promising next-generation energy storage devices to meet the growing need for affordable, highly energy-dense systems for electrical vehicles and grid-scale applications.1,2 The high theoretical gravimetric energy density (1672 mAh g −1 ) of the Li-S system coupled with the low-cost and abundance of sulfur offers significant advantages over current lithium-ion batteries.2 However, the conversion nature of the Li-S system leads to a complicated charge/discharge mechanism that passes through multiple soluble and insoluble species on each halfcycle. 2,3 This opens up a multitude of mechanisms for active material loss during long-term cycling. Additionally, the insulating nature of sulfur and lithium sulfide, the final discharge product, limits the rate capability of the system and necessitates forming composite cathodes with a conductive material such as carbon. 1,2Of particular concern to the loss of capacity with cycling is the deposition of electrochemically-inaccessible solid sulfide species (Li 2 S x , x < 3).4,5 Multiple literature reports have reached different conclusions on the existence of the solid, electrolyte-insoluble species Li 2 S 2 and whether it forms as a solid intermediate during the discharge of Li-S batteries. [5][6][7][8][9][10][11][12] Recent studies have suggested there may be separate reaction pathways that are followed at different points during Li-S discharge: one where only Li 2 S is formed during reduction of soluble polysulfides (Li 2 S x , x > 2), and a second where both Li 2 S and Li 2 S 2 are formed simultaneously. 11 The question of whether any Li 2 S 2 that forms can then be reduced is debated in...

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Discovery of Dual‐Functional Amorphous Titanium Suboxide to Promote Polysulfide Adsorption and Regulate Sulfide Growth in Li–S Batteries

et al. 2022

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Lithium‐sulfur (Li–S) batteries are promising as next‐generation energy storage systems. Adsorbents for sulfide species are favorably applied to the cathode, but this substrate often results in a surface‐passivating lithium sulfide(Li 2 S) film with a strong adsorption of Li 2 S. Here, an amorphous titanium suboxide (a‐TiOx) is presented that strongly adsorbs lithium polysulfides (Li 2 S x , x < 6) but relatively weakly adsorbs to Li 2 S. With these characteristics, the a‐TiO x achieves high conversion of Li 2 S x and high sulfur utilization accompanying the growth of particulate Li 2 S. The DFT calculations present a mechanism for particulate growth driven by the promoted diffusion and favorable clustering of Li 2 S. The a‐TiO x ‐coated carbon nanotube‐assembled film (CNTF) cathode substrate cell achieves a high discharge capacity equivalent to 90% sulfur utilization at 0.2 C. The cell also delivers a high capacity of 850 mAh g –1 even at the ultra‐high‐speed of 10 C and also exhibits high stability of capacity loss of 0.0226% per cycle up to 500 cycles. The a‐TiO x /CNTF is stacked to achieve a high loading of 7.5 mg S cm –2 , achieving a practical areal capacity of 10.1 mAh cm –2 .

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Adsorption of insoluble polysulfides Li₂S_x (x = 1, 2) on Li₂S surfaces

Cited by 57 publications

References 43 publications

Towards Next Generation Lithium-Sulfur Batteries: Non-Conventional Carbon Compartments/Sulfur Electrodes and Multi-Scale Analysis

Towards Next Generation Lithium-Sulfur Batteries: Non-Conventional Carbon Compartments/Sulfur Electrodes and Multi-Scale Analysis

Elucidating the Electrochemical Activity of Electrolyte-Insoluble Polysulfide Species in Lithium-Sulfur Batteries

Discovery of Dual‐Functional Amorphous Titanium Suboxide to Promote Polysulfide Adsorption and Regulate Sulfide Growth in Li–S Batteries

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