Identification and characterization of lithium polysulfides in solution in liquid ammonia

Dubois, Philippe; Lelieur, J. P.; Lepoutre, G.

doi:10.1021/ic00274a017

Cited by 74 publications

(53 citation statements)

References 3 publications

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“…13 This signal is close to a signal at ∼270 nm reported for electrochemically-generated Li 2 S 2 in tetraethylene glycol dimethyl ether (TEGDME). 9 Additional evidence for the formation of Li 2 S 2 was obtained via thermogravimetric analysis (TGA), which showed that the product started to decompose to Li 2 S above 50…”

supporting

confidence: 81%

Section: 2mentioning

confidence: 99%

“…The literature presents several chemical syntheses of Li 2 S 2 , notably by the stoichiometric reaction of sulfur and either lithium or Li 2 S in liquid ammonia at low temperature 13,14 or by the reduction of sulfur with lithium triethylborohydride (Li(C 2 H 5 ) 3 BH) in organic solvents. 15 However, the work first reporting that Li 2 S 2 was formed via Li(C 2 H 5 ) 3 BH reduction was not supported by the characterized data; rather, the product was used as an intermediate to organosulfur compounds.…”

mentioning

confidence: 99%

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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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supporting

confidence: 81%

Section: 2mentioning

confidence: 99%

mentioning

confidence: 99%

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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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“…[41,431 All species S:-in the range x = 1-5 are present in aqueous solution. [43c1 Lelieur et all4'] have also identified the S i -ion in a solution of Li,S, in liquid ammonia, and have established that dissociation of this ion to S;-radicals can occur, giving rise to a characteristic absorption band at 610 nm.…”

Section: Speciationmentioning

confidence: 99%

Solventothermal Synthesis of Solid‐State Chalcogenidometalates

Sheldrick¹,

Wachhold²

1997

Angew. Chem. Int. Ed. Engl.

462

250

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“…The solid is either a polysulfide or a mixture of polysulfide(s) with sulfur, depending on n and on the metal cation M. The spectroscopic studies of Li 2 S n − NH 3 solutions suggest that S 6 2− is the less reduced polysulfide in ammonia [65], but electrochemical experiments show that it is slightly disproportionated [66]. Ammonia is a very useful solvent for the investigation of polysulfides because it allows their synthesis with an easy control of their stoichiometry.…”

Section: Liquid Ammoniamentioning

confidence: 99%

Sulfur

Levillain¹,

Demortier²,

Lelieur³

2006

Encyclopedia of Electrochemistry

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The sections in this article are Introduction Sulfur and Polysulfide Ions in Solution Nonaqueous Solvents Aqueous Solutions Electroreduction of Sulfur and Redox Properties of Polysulfides “Classical” Nonaqueous Solvents Liquid Ammonia Aqueous Solutions Electrooxidation of Sulfur Applied Electrochemistry Electrosynthesis Batteries, Solar Cells, and Sulfurization Environmental Chemistry Conclusion

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Identification and characterization of lithium polysulfides in solution in liquid ammonia

Cited by 74 publications

References 3 publications

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

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

Solventothermal Synthesis of Solid‐State Chalcogenidometalates

Sulfur

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