Cation-Directed Selective Polysulfide Stabilization in Alkali Metal–Sulfur Batteries

Zou, Qingli; Liang, Zhuojian; Du, Guan Ying; Liu, Chi You; Li, Elise Y.; Lu, Yi‐Chun

doi:10.1021/jacs.8b04536

Cited by 77 publications

(61 citation statements)

References 70 publications

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“…3), indicating S 8 2− is more stabilized in such electrolyte environments, that is, with high-DN solvent and/or with strongly solvating cation (TBA + ). 5,32 Other CV analyses such as peak current evaluation using the Randle-Sevcik equation are further illustrated in the supporting information ( Fig. S5 and S6).…”

Section: S •−mentioning

confidence: 99%

Unraveling the Correlation between Solvent Properties and Sulfur Redox Behavior in Lithium-Sulfur Batteries

Gorlin

Patel

et al. 2018

J. Electrochem. Soc.

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119

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Systematic understanding of how solvent property influences Li-S redox chemistry is required to develop an effective electrolyte for Li-S batteries. In this study, we investigate the correlation between solvent property and Li-S redox chemistry in nine non-aqueous electrolyte solvents that cover a wide range of three main solvent physiochemical properties, namely dielectric constant (ε), Gutmann donor number (DN), and acceptor number (AN). We exploit various analytical techniques including cyclic voltammetry, rotating ring disk electrode technique, UV-Vis spectroscopy and galvanostatic measurement in a two-compartment cell. We show that the potential of S 8-reduction increases with increasing AN and that the polysulfide-reduction/oxidation is strongly influenced by the DN. The common discrepancy in the literature on the role of dielectric constant and donor number is addressed by examining the redox reactions, polysulfide stability, and the effect of salt concentration in acetonitrile-a solvent with high dielectric constant and low DN. We show that the DN is the primary descriptor for polysulfide redox reactions, as it controls the effective charge density of the solvated cation (Li +), which affects the stability of polysulfides with different charge density via Pearson's Hard Soft Acid Base theory.

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Section: S •−mentioning

confidence: 99%

Unraveling the Correlation between Solvent Properties and Sulfur Redox Behavior in Lithium-Sulfur Batteries

Gorlin

Patel

et al. 2018

J. Electrochem. Soc.

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119

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“…In fact, the solvation of lithium polysulfides is largely related to the interaction between alkali metal cation and paired polysulfide anion. The larger and higher electropositive cations render stronger cation–anion electrostatic interactions . Although it can induce higher stability and lower solvation of short‐chain LPSs and thus promote the reduction of high‐order LPSs to short‐chain LPSs, the oxidation of short‐chain LPSs to long‐chain LPS becomes turning into a serious headache in the reverse charge process.…”

Section: Sulfur Electrochemistry In Liquid‐electrolyte Li–s Batteriesmentioning

confidence: 99%

Sulfur Redox Reactions at Working Interfaces in Lithium–Sulfur Batteries: A Perspective

Yuan

Peng

Huang

et al. 2019

Adv Materials Inter

142

104

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Lithium–sulfur (Li–S) batteries have been strongly considered as one of the most promising future energy storage systems because of ultrahigh theoretical energy density of 2600 Wh kg−1. The natural abundance, affordable cost, and environmental benignity of elemental sulfur constitute additional advantages. However, complicated reaction behaviors at working electrode/electrolyte interfaces that involve multiphase conversion and multistep ion/electron diffusion during sulfur redox reactions have impeded the thorough understanding of Li–S chemistry and its practical applications. This perspective article highlights the influence of the ion/electron transport and reaction regulation through electrocatalysis or redox mediation at electrode/electrolyte interfaces on various interfacial sulfur redox reactions (liquid–liquid–solid interconversion between soluble lithium polysulfide with different chain lengths and insoluble lithium sulfides in liquid‐electrolyte Li–S batteries and direct solid–solid conversion between sulfur and Li2S in all‐solid‐state Li–S batteries). The current status, existing challenges, and future directions are discussed and prospected, aiming at shedding fresh light on fundamental understanding of interfacial sulfur redox reactions and guiding the rational design of electrode/electrolyte interfaces for next‐generation Li–S batteries with high energy density and long cycle life.

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“…TMU exhibited favorable Li 2 Sdeposition kinetics and better compatibility toward lithium anode than other high-e solvents.Atanelectrolyte-starved condition, the LiÀS pouch cell realized ahigh sulfur utilization of 91 %and ahigh energy density of 324 Wh kg À1 ,o ffering ap romising route toward practical high-energy Li À Sb atteries.H owever, extended cycling was still hindered due to the electrolyte depletion at harsh conditions.Therefore,when decreasing the E/S ratio for LiÀSb atteries,t he electrolyte consumption at the anode must also be considered. Ongoing efforts in developing the radical-directed concept for electrolytestarved and high-energy Li À Sb atteries could be 1) tuning the cation/anion couples for radical stabilization rather than high-e solvents that are more aggressive toward lithium; [23] 2) localizing the reactive high-e solvents through high salt concentration and co-solvent engineering; [24] and 3) protecting the lithium via artificial SEI. [21,25] Besides,i nsitu or operando characterization is required for sulfur speciation and mechanism validation in working cells with extreme operating conditions that simulate the reality.…”

Section: Angewandte Chemiementioning

confidence: 99%

“…Ongoing efforts in developing the radical-directed concept for electrolytestarved and high-energy Li À Sb atteries could be 1) tuning the cation/anion couples for radical stabilization rather than high-e solvents that are more aggressive toward lithium; [23] 2) localizing the reactive high-e solvents through high salt concentration and co-solvent engineering; [24] and 3) protecting the lithium via artificial SEI. TMU exhibited favorable Li 2 Sdeposition kinetics and better compatibility toward lithium anode than other high-e solvents.Atanelectrolyte-starved condition, the LiÀS pouch cell realized ahigh sulfur utilization of 91 %and ahigh energy density of 324 Wh kg À1 ,o ffering ap romising route toward practical high-energy Li À Sb atteries.H owever, extended cycling was still hindered due to the electrolyte depletion at harsh conditions.Therefore,when decreasing the E/S ratio for LiÀSb atteries,t he electrolyte consumption at the anode must also be considered.…”

mentioning

confidence: 99%

The Radical Pathway Based on a Lithium‐Metal‐Compatible High‐Dielectric Electrolyte for Lithium–Sulfur Batteries

et al. 2018

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High-dielectric solvents were explored for enhancing the sulfur utilization in lithium-sulfur (LiÀS) batteries,b ut their applications have been impeded by lows tability at the lithium metal anode.N ow ar adical-directed, lithium-compatible,and strongly polysulfide-solvating high-dielectric electrolyte based on tetramethylurea is presented. Over 200 hours of cycling was realized in Li j Li symmetric cells,s howing good compatibility of the tetramethylurea-based electrolyte with lithium metal. The high solubility of short-chain polysulfides, as well as the presence of active S 3 C À radicals,e nabled pouch cells to deliver ad ischarge capacity of 1524 mAh g À1 and an energy density of 324 Wh kg À1 .T his finding suggests an alternative recipe to ether-based electrolytes for Li À Sbatteries.The rapidly growing global demand for energy appeals for advanced energy storage systems beyond current lithium-ion batteries.T he lithium metal anode is regarded as the cornerstone of next-generation secondary batteries. [1] To fully exert the virtue of high-capacity lithium anode,h igh-capacity cathode materials like sulfur are strongly preferred. Benefiting from the multi-electron conversion reactions,t he sulfur cathode delivers at heoretical capacity of 1675 mAh g À1 ,a nd endows lithium-sulfur (LiÀS) batteries with ar emarkable energy density up to 2600 Wh kg À1 ,f ar exceeding the theoretical limits of lithium-ion batteries. [2] Substantial efforts have been dedicated in the past decade to addressing the issues of LiÀSb atteries,s uch as the insulating sulfur compounds and the shuttle effect. [3] Despite these efforts,t here is still ah uge gap between the practical energy density and the theoretical value,o wing to 1) low sulfur utilization, 2) undesirable sulfur content, 3) low areal loading of sulfur,4)large excess of lithium anode,and 5) large electrolyte-to-sulfur mass ratio (E/S ratio). [4] Among them, E/ Sr atio and sulfur utilization have the most significant implications on energy density (Supporting Information, Figure S1). [5] Nevertheless,l ow E/S ratio is always counterbalanced by the simultaneous decline of sulfur utilization in conventional ether-based electrolytes.Therefore,understanding the interplay between electrolyte and sulfur species and further rationalizing the electrolyte recipe appears to be crucial and urgent to close the gap.Thecounterbalance between low E/S ratio and high sulfur utilization is essentially associated with the solvation of sulfur species in electrolytes.O wing to the medium polarity (a dielectric constant, e,ofaround 7at258 8C), the most common dimethoxyethane (DME)/dioxolane (DOL) electrolyte only allows moderate solvation of polysulfides,always resulting in cathode passivation via the early precipitation of lowsolubility short-chain polysulfides (Li 2 S n , n 4; Supporting Information, Figure S2a). [6] To circumvent this dilemma, one approach is to decouple the reaction of elemental sulfur from polysulfide dissolution through non/sparsely polysulfide-solvating electrolytes (Su...

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Cation-Directed Selective Polysulfide Stabilization in Alkali Metal–Sulfur Batteries

Cited by 77 publications

References 70 publications

Unraveling the Correlation between Solvent Properties and Sulfur Redox Behavior in Lithium-Sulfur Batteries

Unraveling the Correlation between Solvent Properties and Sulfur Redox Behavior in Lithium-Sulfur Batteries

Sulfur Redox Reactions at Working Interfaces in Lithium–Sulfur Batteries: A Perspective

The Radical Pathway Based on a Lithium‐Metal‐Compatible High‐Dielectric Electrolyte for Lithium–Sulfur Batteries

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