On the Electrode Potentials in Lithium-Sulfur Batteries and Their Solvent-Dependence

Schneider, Holger; Gollub, C.; Weiß, Thomas; Kulisch, Joern; Leitner, Klaus; Schmidt, R.; Safont-Sempere, Marina M.; Mikhaylik, Yuriy; Kelley, Tracy; Scordilis‐Kelley, Chariclea; Laramie, Mike; Du, Hui

doi:10.1149/2.0991409jes

Cited by 37 publications

(45 citation statements)

References 75 publications

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“…Electrolyte decomposition measurements with a mass spectroscope give strong indications that LiNO 3 is responsible for the N 2 gas creation. [ 9 ] As a result there is still no effi cient and cheap means to solve the Li-S shuttle mechanism without a severe drawback.…”

Section: Statistical Overview Of Li-s Literaturementioning

confidence: 99%

Lithium–Sulfur Cells: The Gap between the State‐of‐the‐Art and the Requirements for High Energy Battery Cells

Hagen

Hanselmann

Ahlbrecht

et al. 2015

Advanced Energy Materials

589

659

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For a mass commercialization of Li-S chemistry the gravimetric energy density must be clearly above that of state-of-theart lithium-ion cells (with the Panasonic NCR18650B as current energy density champion) to compensate for the much lower cycle stability. The number 18650 describes the cell's shape with a diameter of ≈18 mm and a height of ≈65 mm. The NCR18650B provides a capacity of ≈3.3Ah with a nominal voltage of 3.6 V resulting in a gravimetric energy density of ≈240 Wh kg −1 and a volumetric energy density of ≈670 Wh L −1 . Additionally, the corresponding cell type can achieve several hundred cycles until 80% of the initial capacity is reached. By contrast, although high cycle numbers are reported for Li-S cells in the literature, the fl aw is that these high cycle numbers are only obtained because of an excess of lithium, an excess of electrolyte and low sulfur areal loads, [ 7 ] resulting in very poor potential gravimetric energy density. Figure 1 shows the gravimetric and volumetric energy density of various electrochemical energy storage systems. The Li-S cell manufacturers Sion Power and Oxis Energy expect that future Li-S cells will have a volumetric energy density comparable to that of state-of-the-art Li-ion cells (≈700 Wh L −1 ) but more than twice the gravimetric energy density with values of 400-600 Wh kg −1 .The scope of this article can be summarized as follows:• A Li-S review will be provided focusing on statistical information like sulfur load and sulfur electrode fraction which determine the energy density and discussing the state-of-theart of the worldwide Li-S research.• By opening an NCR18650B we obtained information about the passive weight distribution of state-of-the-art high energy 18650 cells. With this information we were able to calculate the possible energy densities and prices of future Li-S cells for various sulfur loads, sulfur utilizations, and electrolyte/ sulfur (E/S) ratios. Keeping in mind that a Li-S cell must have a superior gravimetric energy density to the NCR18650B these results provide insights into which electrode properties and electrochemical results must be obtained. Additionally, they allow an evaluation of the state of the art of international scientifi c Li-S research.• Finally, an electrode that meets important demands for high gravimetric energy densities is introduced. Li-S cells

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Section: Statistical Overview Of Li-s Literaturementioning

confidence: 99%

Lithium–Sulfur Cells: The Gap between the State‐of‐the‐Art and the Requirements for High Energy Battery Cells

Hagen

Hanselmann

Ahlbrecht

et al. 2015

Advanced Energy Materials

589

659

View full text Add to dashboard Cite

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“…The variation in dynamic equilibrium, redox chemistry, and kinetics of sulfur and polysulfi des is strongly affected by solvent complexation, meaning that solvents have a signifi cant effect on the electrochemical performance of Li-S batteries. [ 52,69,70,[159][160][161] In particular, liquid electrolyte is critical in Li-S batteries because the intermediate polysulfi des could dissolve in it. This dissolution could lead to several serious problems, including change of cathode morphology; side reactions of the polysulfi de species, such as their disproportionation and attack of the electrolyte solvents; polysulfi de shuttle reactions; and passivation of the lithium metal anode.…”

Section: Solvents' Impact On the Dissolved Polysulfi De Speciesmentioning

confidence: 99%

Progress in Mechanistic Understanding and Characterization Techniques of Li‐S Batteries

Lü

Amine

2015

Advanced Energy Materials

448

336

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Rechargeable lithium‐sulfur batteries that operate at room temperature have attracted much research interest as next‐generation energy storage systems. Although tremendous advances have been made with Li‐S batteries, great challenges still exist in achieving high capacity, high loading, high coulombic efficiency, and long cycle life. These challenges arise from the system complexity, lack of mechanistic understanding of the redox reaction, and operational limitations of Li‐S cells. The focus here is on the recent gains in fundamental understanding of the Li‐S redox reaction mechanism based on the application of advanced characterization techniques. Research results that help with the understanding of the close relationship between cell design (including development of new and advanced electrode materials, electrolytes, separators, binders, and cell configurations), the Li‐S reaction mechanism, characterization methods, and Li‐S battery performance are discussed.

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“…39 Solvation of lithium cations in diglyme containing electrolytes are stronger than in the ionic liquid Pyr 14 TFSI; consequently, E 0' (Li + /Li) is lower in diglyme containing electrolytes, and as a result, the measured redox potential of Co(Terp) 2 and TTF measured vs. Li + /Li decreases with the addition of more Pyr 14 TFSI (see Figure S3 for schematic description). similarly report negligible influence of the mediator on the discharge voltage.…”

Section: Resultsmentioning

confidence: 99%

Utilization of Cobalt Bis(terpyridine) Metal Complex as Soluble Redox Mediator in Li–O₂ Batteries

et al. 2016

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Redox mediators hold significant promise in reducing the large overpotentials pervasive upon charging of lithium-oxygen (Li-O 2 ) cells. Cobalt bis(terpyridine) (Co(Terp) 2 ) was investigated as mediator of the Li-O 2 charging reaction using electrochemical, XRD and mass spectrometry measurements and benchmarked against tetrathiafulvalene (TTF). Significant reductions in reversible potential versus Li + /Li are measured for Co(Terp) 2 and TTF from diglyme to Pyr 14 TFSI:diglyme to Pyr 14 TFSI, attributable to upward shift in the Li + /Li electrode, due to weakening Li + solvation in this solvent order. Lowering of the reversible potentials has noticeable gains on the kinetics of the charge reaction and greater reduction in charge overpotential are observed with the cobalt complex. However, using differential electrochemical mass spectrometry reveal that less than 25% of the O 2 consumed on discharge is recovered on charge in presence of Co(Terp) 2 , while TTF enables up to 32% O 2 recovery on charge. CO 2 is a significant charging product at voltages greater than 4.0 V vs. Li + /Li because of electrolyte decomposition. Further work is required in order to develop mediators with 100% of oxygen evolution efficiency, and the present finding of the possibility to tune the reversible redox potential of the mediator by changing the solvent will be very useful to achieve this formidable task.

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On the Electrode Potentials in Lithium-Sulfur Batteries and Their Solvent-Dependence

Cited by 37 publications

References 75 publications

Lithium–Sulfur Cells: The Gap between the State‐of‐the‐Art and the Requirements for High Energy Battery Cells

Lithium–Sulfur Cells: The Gap between the State‐of‐the‐Art and the Requirements for High Energy Battery Cells

Progress in Mechanistic Understanding and Characterization Techniques of Li‐S Batteries

Utilization of Cobalt Bis(terpyridine) Metal Complex as Soluble Redox Mediator in Li–O₂ Batteries

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On the Electrode Potentials in Lithium-Sulfur Batteries and Their Solvent-Dependence

Cited by 37 publications

References 75 publications

Lithium–Sulfur Cells: The Gap between the State‐of‐the‐Art and the Requirements for High Energy Battery Cells

Lithium–Sulfur Cells: The Gap between the State‐of‐the‐Art and the Requirements for High Energy Battery Cells

Progress in Mechanistic Understanding and Characterization Techniques of Li‐S Batteries

Utilization of Cobalt Bis(terpyridine) Metal Complex as Soluble Redox Mediator in Li–O2 Batteries

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Product

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About

Utilization of Cobalt Bis(terpyridine) Metal Complex as Soluble Redox Mediator in Li–O₂ Batteries