Lithium Polysulfide Radical Anions in Ether-Based Solvents

Wujcik, Kevin H.; Wang, Dunyang Rita; Raghunathan, Aditya; Drake, Melanie; Pascal, Tod A.; Prendergast, David; Balsara, Nitash P.

doi:10.1021/acs.jpcc.6b04264

Cited by 67 publications

(68 citation statements)

References 47 publications

(98 reference statements)

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“…Considering that the formed radical species are usually favorable for the electrochemical pathways. Wujcik et al examined the presence of radical polysulfide species in ether‐based solvents (tetraethylene glycol dimethyl ether and poly(ethylene oxide)) via a combination of EPR and ultraviolet–visible (UV–Vis) spectroscopy (Figure c,d) . EPR and UV–Vis results verified the presence of radical species in ether‐based electrolytes.…”

Section: Advanced Characterization and Mechanism Research In Li–s Batmentioning

confidence: 98%

“…c) EPR spectra obtained for tetraethylene glycol dimethyl ether (TEGDME) and poly(ethylene oxide) (PEO) lithium polysulfide solutions for x mix values of 6. d) UV–vis spectra obtained for TEGDME and PEO lithium polysulfide solutions at sulfur concentrations of 10 × 10 −3 m . Reproduced with permission . Copyright 2016, American Chemical Society.…”

Section: Advanced Characterization and Mechanism Research In Li–s Batmentioning

confidence: 99%

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Advanced Characterization Techniques in Promoting Mechanism Understanding for Lithium–Sulfur Batteries

Zhao

Nie

et al. 2018

Adv Funct Materials

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Due to their numerous advantages, such as high specific capacity, lithiumsulfur batteries (Li-S batteries) have attracted much attention as nextgeneration energy storage systems. To meet future needs for commercial application, Li-S batteries will require both improved cycle life and high energy density. It is of critical importance to understand the fundamental mechanisms in Li-S systems to further improve the overall battery performance. Various advanced characterization techniques, over the past few years, have proven their important role in promoting the mechanism understanding for Li-S batteries. Here, the recent progress of mechanism understanding, including redox reactions, Li polysulfides dissolution, etc., in Li-S systems based on the advanced characterization techniques is reviewed. Special focus is placed on how these advanced characterization techniques are being employed and what characteristic or capability they possess. The importance of the combination of multiple characterization techniques, differences between ex situ and in situ experimental methods, as well as effects of characterization conditions in Li-S batteries are also discussed.

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Section: Advanced Characterization and Mechanism Research In Li–s Batmentioning

confidence: 98%

Section: Advanced Characterization and Mechanism Research In Li–s Batmentioning

confidence: 99%

Advanced Characterization Techniques in Promoting Mechanism Understanding for Lithium–Sulfur Batteries

Zhao

Nie

et al. 2018

Adv Funct Materials

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“…Impedance spectroscopy has also been used to evaluate the individual contributions from electrolyte resistance, charge transfer, ion diffusion and electrode surface layers, which in turn has been used to refine mechanistic models of Li−S cells,, as well as to investigate capacity fading . Other experimental techniques used to elucidate redox and diffusion properties in Li−S cells include XAS, in‐operando optical imaging of the temporal and spatial distribution of polysulfides, UV‐Vis spectroscopy, NMR, EPR/ESR,, XRD, Raman, HPLC, and gas evolution, among other electrochemical studies . The mechanism and kinetics of Li 2 S precipitation has been studied using chronoamperometry .…”

Section: Introductionmentioning

confidence: 99%

Quantitative Galvanostatic Intermittent Titration Technique for the Analysis of a Model System with Applications in Lithium−Sulfur Batteries

et al. 2017

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The galvanostatic intermittent titration technique (GITT) is a powerful characterization tool for batteries, which provides key thermodynamic and kinetic information about battery performance. However, the quantitative analysis of GITT measurements for lithium−sulfur batteries has so far been limited to the evaluation of the internal resistance of the cell and the equilibrium voltage profiles. In this work, we provide the mathematical framework to characterize the mass‐transport kinetics in lithium−sulfur batteries from GITT data, and we demonstrate the validity of the approach through the application to a model and well‐behaved system, ethyl viologen, whose diffusion coefficient is corroborated by cyclic voltammetry data. The present approach is also advantageous for the analysis of ion‐insertion electrodes, where non‐linearity of concentration and voltage changes would produce unrealistic evaluations of the diffusion coefficient by the classical analysis of GITT data.

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“…PEO can possibly promote the formation of lithium polysulfide radicals, as found in Ref. 28. The authors showed, by ab-initio simulation, that the -C=O groups in PVP exhibit high binding energies of 1.14 and 1.30 eV with Li 2 S and PS radical species.…”

Section: Resultsmentioning

confidence: 73%

Improving the Durability and Minimizing the Polysulfide Shuttle in the Li/S Battery

Peled

Shekhtman

Mukra

et al. 2017

J. Electrochem. Soc.

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The effect of surfactants and protective interlayers (commercial carbon paper and homemade mixed-conduction composites) on the electrochemical performance of sulfur batteries has been studied. Modification of cell configuration by the insertion of Toraycarbon paper between the cathode and separator improved the utilization of the active material and increased the initial discharge capacity from 800 to 1400 mAh/gS. The latter is about 84% of the theoretical value. The use of a few-micron-thick PEO-PVP-XC72 or SWCNT-PVP interlayer composites, cast on the cathode or separator, resulted in a similar positive effect on the initial sulfur utilization. The cells that were assembled in the discharge state and contained carbon interlayers exhibited a faradaic efficiency (FE) of above 99%, while the FE of the cells with the unprotected cathode is 95-96%. High faradaic efficiencies confirm the functionality of protective interlayers, which minimizes the polysulfide shuttle. Analysis of the impedance spectra of the conventional and modified cells shows that the SEI resistance decreases by about 50% and the apparent thickness of the SEI becomes smaller in the interlayer-protected cells. The cells with ultrathin composite layers hold the 30% capacity gain induced by the barrier for at least 400 cycles. The first publication on the soluble lithium polysulfides (PS) -cell is by Abraham et al. 1 The first carbon-loaded-sulfur primary and secondary batteries were presented by Peled in 1983 2 and 1989, 3 respectively. Both batteries consisted of sulfur embedded in a porous carbon matrix. As the development of lithium-ion technology began in the early 1990 s, fewer efforts were made on the Li-S system. However, since the 2000 s and especially in recent years, Li-S technology has regained scientific interest as the post lithium-ion battery. A high theoretical specific energy of 2600 Wh/kg and 2200 Wh/L, combined with inexpensive and safe raw materials, classifies the lithium/sulfur battery as a leading candidate to replace the common lithium-ion battery in many applications. Although considered a promising battery, the lithium/sulfur battery suffers from three main drawbacks, which include 80% volume expansion of the cathode during discharge, the insulating nature of the sulfur species and the solubility of sulfur and of lithium polysulfides in the electrolyte. The insulating nature of the active material requires the use of nanosize sulfur species and the addition of relatively large amounts of conductive materials, such as black carbons, which lowers both the gravimetric and the volumetric energy density of the battery. The expansion/extraction of the cathode may lead to cracks in its structure, thus reducing the durability of the cell as a result of the loss of electrical contact between the particles of the active cathode material, and between the cathode and current collector. The solubility of polysulfides leads to the loss of active cathode material followed by the irreversible capacity loss. During charging, long polysu...

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Lithium Polysulfide Radical Anions in Ether-Based Solvents

Cited by 67 publications

References 47 publications

Advanced Characterization Techniques in Promoting Mechanism Understanding for Lithium–Sulfur Batteries

Advanced Characterization Techniques in Promoting Mechanism Understanding for Lithium–Sulfur Batteries

Quantitative Galvanostatic Intermittent Titration Technique for the Analysis of a Model System with Applications in Lithium−Sulfur Batteries

Improving the Durability and Minimizing the Polysulfide Shuttle in the Li/S Battery

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