Structural Design of Cathodes for Li‐S Batteries

Pope, Michael A.; Aksay, İlhan A.

doi:10.1002/aenm.201500124

Cited by 418 publications

(335 citation statements)

References 117 publications

(389 reference statements)

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“…This lower sulfur utilization with the LiTDI-based electrolyte may be attributed to the low solubility of the polysulfi des, especially the longer chain polysulfi des. [ 33,34 ] Figure 3 compares the charge-discharge curves and cycling performance of a cell with 3 mg S cm −2 loading. When sulfur to electrolyte ratio is increased from 50 g S /L E to 70 g S /L E in the cell using LiTDI electrolyte, a higher Coulombic effi ciency (CE) and slower capacity decay are obtained (Figure 2 b).…”

mentioning

confidence: 99%

Restricting the Solubility of Polysulfides in Li‐S Batteries Via Electrolyte Salt Selection

Chen

Han

Henderson

et al. 2016

Advanced Energy Materials

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1 M lithium bis(trifl uoromethanesulfonyl)imide (LiTFSI) in 1,3-dioxolane/1,2-dimethoxyethane (DOL/DME). [ 21 ] Switching to other solvents with high dielectric constant such as dimethyl sulfoxide (DMSO) or dimethylacetamide (DMA) facilitates the production of sulfur radicals and the full utilization of the sulfur, but the cycling stability of the cell is also sacrifi ced and the unstable interface between the reactive DMSO/DMA solvent and Li metal raises other concerns. [ 22,23 ] Alternative cell designs incorporating solid-state electrolytes completely prevent the dissolution of polysulfi des, but the utilization of the sulfur (i.e., the reversible capacity) is also largely reduced. [ 24 ] Therefore, the solubility of the polysulfi des in cells with liquid electrolytes needs to be carefully tuned and well understood. In most studies, a low sulfur loading (less than 1 mg cm -2 ) is used, but a high S loading is desired for high-capacity full cells. [ 25,26 ] In this paper, lithium trifl uoromethyl-4,5-dicyanoimidazole (LiTDI) is studied for Li-S cells. We study the effect of LiTDI on the solubility of polysulfi des. The performance of this electrolyte was investigated with a high sulfur (i.e., practically usable) loading at 3 mg cm -2 under a high current density.A comparison of the physical properties of electrolytes with either 1 M LiTFSI or LiTDI in DOL/DME (1/1, v/v) is shown in Table 1 . Both electrolytes have a comparable conductivity and viscosity, suitable for the electrochemical needs, but an 83% decrease in the Li 2 S 8 solubility is observed in the LiTDI electrolyte. Restricting the polysulfi de solubility to a low level is expected to improve the Li-S cell cycle life because of the suppression of the polysulfi de shuttle mechanism, reduction of anode contamination, and the minimization of the loss of active material from the cathode. [ 22 ] To understand the relationship between the polysulfi de solubility and electrolyte supporting salt, 7 Li and 17 O nuclear magnetic resonance (NMR) spectroscopic measurements were used to aid in understanding the solvation interactions. The δ ( 7 Li) for the LiTDI and LiTFSI-based electrolytes without polysulfi des was -0.8 and -1.2 ppm (relative to Li + cations fully solvated by H 2 O molecules) ( Figure 1 a-c), respectively. The δ ( 17 O) for the DME molecules shifts to ≈ -27.7 and -26.9 ppm in the LiTDI and LiTFSI-based electrolytes, respectively, from -24.3 ppm in a neat DOL/DME solvent mixture. The δ ( 17 O) for the DOL molecules near 35 ppm shifts by 1-2 ppm. The smaller shift of δ ( 17 O) for the DOL molecules relative to the DME molecules and signifi cant broadening of the peaks for the latter suggest that the Li + cations may be preferentially solvated by the DME. [ 27 ] It has been reported that the solvation of Li + cations in the electrolyte affects the short-chain polysulfi de solubility by solvating the Li + ion in the polysulfi des, but it did not affect the

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confidence: 99%

Restricting the Solubility of Polysulfides in Li‐S Batteries Via Electrolyte Salt Selection

Chen

Han

Henderson

et al. 2016

Advanced Energy Materials

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“…This is different from the intercalation and deintercalation mechanisms of lithium ions in LIBs whose theoretical energy density is limited to ~420 Wh kg −1 or ~ 1400 Wh L −1 [18][19][20]. In terms of cathode materials for lithium batteries, sulfur cathodes possess high theoretical specific capacities of up to 1672 mAh g −1 and are nearly an order of magnitude higher than that of traditional cathode materials in LIBs such as LiCoO 2 , LiMn 2 O 4 and LiFePO 4 [14,[21][22][23][24]. And because of this, Li-S battery cells using lithium metal anodes and sulfur cathodes with an average cell voltage of 2.15 V versus Li + /Li can provide theoretical specific energy densities of ~2500 Wh kg −1 and volumetric energy densities of~2800 Wh L −1 [17,[25][26][27].…”

Section: Introductionmentioning

confidence: 91%

“…Unlike traditional LIBs, carbonate-based electrolytes are unsuitable for Li-S batteries because of the chemical instability of polysulfides in these types of electrolytes. Therefore, carbonate-based electrolytes are replaced by inert ether-based electrolytes that are composed of dimethoxyethane and dioxolane by using lithium bis-trifluoromethane sulfonimide as an electrolyte conductive agent [13,14,53,54]. However, although numerous Li-S battery studies employ ether-based electrolytes, carbonate-based electrolytes do possess comparative advantages including the limited solubility of polysulfide intermediates as compared with ether-based electrolytes, reducing shuttle effects [55,56].…”

Section: Electrochemical Reactions and Challenges Of Li-s Batteriesmentioning

confidence: 99%

“…The lithium sulfur (Li-S) battery system is one such advanced battery system that is regarded as a promising next-generation energy storage system because of its higher theoretical energy density in comparison with LIBs [11][12][13][14]. The investigation of Li-S batteries can be traced back to the 1960s with breakthroughs made in 2009 by Nazar et al [15][16][17] who synthesized mesoporous carbon sulfur composites as cathode materials in Li-S batteries and reported high specific capacities and stable cycling performances.…”

Section: Introductionmentioning

confidence: 99%

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Multifunctionality of Carbon-based Frameworks in Lithium Sulfur Batteries

Tang

Hou

2018

Electrochem. Energ. Rev.

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Compared with conventional lithium ion batteries (LIBs), lithium sulfur (Li-S) batteries possess advantages such as higher theoretical energy densities and better cost efficiencies, making them promising next-generation energy storage systems. However, the commercialization of Li-S batteries is impeded by several drawbacks, including low cycling stabilities, limited sulfur utilizations, existing shuttle effects of polysulfide intermediates, serious safety concerns, as well as inferior cycling performances of lithium metal anodes. To address these issues, researchers have achieved rapid developments for sulfur cathodes and increased their attention to lithium metal anodes to facilitate the widespread application of Li-S batteries. And among the substrate materials for electrodes in Li-S batteries being developed, carbon-based materials have been especially promising because of their multifunctionality, demonstrating great potential for application in advanced energy storage and conversion systems. In this review, recent advancements of carbon-based frameworks applied to Li-S batteries will be summarized and diverse utilization methods of these carbon-based materials for both sulfur cathodes and lithium metal anodes will be provided. Future research directions and the prospects of Li-S batteries with high performance and practicability will also be discussed. Keywords

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“…The charge-discharge test using the VGCF μ -H modified electrode was performed with the electric charge of 3.6 C cm ¹2 (= 1 mAh cm ¹2 ) for deposition of Li to meet the large specific capacity of Li-S batteries, 24 while the cell with the Cu electrode short-circuited before reaching the electric charge of 3.6 C cm…”

Section: ¹2mentioning

confidence: 99%

Electrochemical Deposition and Dissolution of Lithium on a Carbon Fiber Composite Electrode in a Solvate Ionic Liquid

et al. 2017

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Electrochemical deposition and dissolution of Li metal on a carbon fiber composite electrode were investigated in lithium bis(trifluoromethylsulfonyl)amide-tetraglyme solvate ionic liquid electrolyte. The carbon fiber composite coated on a Cu substrate was composed of vapor-grown carbon fiber (VGCF ® -H) and poly(vinylidene fluoride). The coulombic efficiency for dissolution of Li deposits on the VGCF ® -H modified Cu electrode was kept more than 98% at 100th cycle and higher than that on a Cu electrode in the solvate ionic liquid. Li was deposited in the porous structure of the VGCF ® -H modified Cu electrode and scarcely observed on the surface of the VGCF ® -H modified Cu probably because the overpotential for the reduction of Li is smaller on the Cu substrate and/or deposited Li than that on the cylindrical basal plane of VGCF ® -H. This result suggests that the voids in the carbon fiber network effectively act as the Li deposition sites at the electrode|separator interface in the coin cell.

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Structural Design of Cathodes for Li‐S Batteries

Cited by 418 publications

References 117 publications

Restricting the Solubility of Polysulfides in Li‐S Batteries Via Electrolyte Salt Selection

Restricting the Solubility of Polysulfides in Li‐S Batteries Via Electrolyte Salt Selection

Multifunctionality of Carbon-based Frameworks in Lithium Sulfur Batteries

Electrochemical Deposition and Dissolution of Lithium on a Carbon Fiber Composite Electrode in a Solvate Ionic Liquid

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