A Selection Rule for Hydrofluoroether Electrolyte Cosolvent: Establishing a Linear Free‐Energy Relationship in Lithium–Sulfur Batteries

Su, Chi‐Cheung; He, Meinan; Amine, Rachid; Amine, Khalil

doi:10.1002/anie.201904240

Cited by 41 publications

(37 citation statements)

References 44 publications

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“…The dilution effect has been examined by considering five different fluorinated ether molecules. Among them, three common HFEs (viz, ETE, BTFE, TTE), which have been actually studied 10 , 12 , 17 . In addition, we introduced, for the first time, two other fluorinated diethyl ether molecules, bis(1,1,2,2-tetrafluoro ethyl) ether (B2E) and bis(pentafluoro ethyl) ether (BPE) that consist of eight and ten fluorine atoms, respectively (Table 1 ).…”

Section: Resultsmentioning

confidence: 99%

“…However, the practical application of nonflammable HC electrolyte still suffers from some limitations as the low ionic conductivity and the high viscosity of the electrolyte 4 , 5 . In challenges to overcome these drawbacks, some researchers are focusing on the promising approach of dilution 9 – 17 . In fact, the selection and designing of diluents are very important to improve transports properties of electrolyte anions without losing their nonflammability characteristic and the formation of stable salt-derived SEI film 11 , 12 .…”

Section: Introductionmentioning

confidence: 99%

“…In fact, the selection and designing of diluents are very important to improve transports properties of electrolyte anions without losing their nonflammability characteristic and the formation of stable salt-derived SEI film 11 , 12 . Among them, hydrofluoroethers (HFEs) were widely used as diluent co-solvents 9 , 10 , 12 – 17 because of their low solvating ability 9 , 10 , 14 , 15 . HFEs showed a high ability to enhance the oxidative stability of the electrolytes 13 , excellent thinning reagents for reducing the viscosity of electrolytes 14 and to construct a localized-concentrated electrolyte, which is strongly requested for the formation of a stable salt-derived SEI film 9 , 12 , 16 .…”

Section: Introductionmentioning

confidence: 99%

“…HFEs showed a high ability to enhance the oxidative stability of the electrolytes 13 , excellent thinning reagents for reducing the viscosity of electrolytes 14 and to construct a localized-concentrated electrolyte, which is strongly requested for the formation of a stable salt-derived SEI film 9 , 12 , 16 . Regarding the general structure of HFEs, the common HFEs were classified according to the vicinity of the fluoroalkyl groups to the oxygen atom 17 . The HFEs, with the closest position of a fluoroalkyl group to the oxygen atom, showed the lowest lithium-solvating power, while the distant fluoroalkyl-substituted HFEs, as bis(2,2,2-trifluoroethyl) ether (BTFE), did the opposite effect in addition to the highest conductivity 17 .…”

Section: Introductionmentioning

confidence: 99%

“…Regarding the general structure of HFEs, the common HFEs were classified according to the vicinity of the fluoroalkyl groups to the oxygen atom 17 . The HFEs, with the closest position of a fluoroalkyl group to the oxygen atom, showed the lowest lithium-solvating power, while the distant fluoroalkyl-substituted HFEs, as bis(2,2,2-trifluoroethyl) ether (BTFE), did the opposite effect in addition to the highest conductivity 17 . Also, ethyl 1,1,2,2-tetrafluoroethyl ether (ETE) showed a high ionic conductivity in addition to BTFE for acetonitrile-based electrolytes 10 .…”

Section: Introductionmentioning

confidence: 99%

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Theoretically predicting the feasibility of highly-fluorinated ethers as promising diluents for non-flammable concentrated electrolytes

Bouibes

Saha

Nagaoka

2020

Sci Rep

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The practical application of nonflammable highly salt-concentrated (HC) electrolyte is strongly desired for safe Li-ion batteries. Not only experimentalists but also theoreticians are extensively focusing on the dilution approach to address the limitations of HC electrolyte such as low ionic conductivity and high viscosity. This study suggests promising highly-fluorinated ethers to dilute the HC electrolyte based on non-flammable trimethyl phosphate (TMP) solvent. According to the quantum mechanical and molecular dynamics calculations, the fluorinated ether diluents showed a miscibility behavior in HC TMP-based electrolyte. While such miscibility behavior of the diluent with TMP solvent has been significantly enhanced by increasing its degree of fluorination, i.e., the “fluorous effect”, it is remarkable that the self-diffusion constant of Li+ and the ionic conductivity should be significantly improved by dilution with bis(1,1,2,2-tetrafluoro ethyl) ether (B2E) and bis(pentafluoro ethyl) ether (BPE) compared to other common hydrofluoroether diluents. In addition, the fluorinated-ether diluents have high ability to form a localized-concentrated electrolyte in HC TMP-based solution, leading to high expectation for the formation of a stable and a compact inorganic SEI film.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Theoretically predicting the feasibility of highly-fluorinated ethers as promising diluents for non-flammable concentrated electrolytes

Bouibes

Saha

Nagaoka

2020

Sci Rep

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Low‐Density Fluorinated Silane Solvent Enhancing Deep Cycle Lithium–Sulfur Batteries’ Lifetime

Liu

Shi

et al. 2021

Advanced Materials

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The lithium metal anode (LMA) instability at deep cycle with high utilization is a crucial barrier for developing lithium (Li) metal batteries, resulting in excessive Li inventory and electrolyte demand. This issue becomes more severe in capacity‐type lithium–sulfur (Li–S) batteries. High‐concentration or localized high‐concentration electrolytes are noted as effective strategies to stabilize Li metal but usually lead to a high electrolyte density (>1.4 g mL−1). Here we propose a bifunctional fluorinated silane‐based electrolyte with a low density of 1.0 g mL−1 that not only is much lighter than conventional electrolytes (≈1.2 g mL−1) but also form a robust solid electrolyte interface to minimize Li depletion. Therefore, the Li loss rate is reduced over 4.5‐fold with the proposed electrolyte relative to its conventional counterpart. When paired with onefold excess LMA at the electrolyte weight/cell capacity (E/C) ratio of 4.5 g Ah−1, the Li–S pouch cell using our electrolyte can survive for 103 cycles, much longer than with the conventional electrolyte (38 cycles). This demonstrates that our electrolyte not only reduces the E/C ratio but also enhances the cyclic stability of Li–S batteries under limited Li amounts.

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Influence of Primary Particle Morphology and Hydrophilicity of Carbon Matrix on Electrode Coating Quality and Performance of Practical High‐Energy‐Density Li–S Batteries

Li,

Chen,

Yamamoto

et al. 2024

Adv Materials Inter

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Li–S batteries have attracted attention as the next‐generation secondary batteries. While substantial progress is made in understanding Li–S chemistry at a fundamental level, only a limited number of studies are dedicated to achieving high energy density at the practical pouch cell level. The challenge lies in attaining high‐energy‐density Li–S batteries under harsh conditions, which involve a minimal amount of electrolyte and a relatively high areal S‐loading cathode. This discrepancy creates a substantial gap between fundamental material research and comprehensive cell‐level investigations. In this study, it is investigated how the morphology and properties of two carbon materials, namely Ketjen black (KB) and mesoporous carbon nano‐dendrites (MCND), influence the composite cathode architecture and determine the performance of Li–S batteries. Unlike KB, MCND allows for a higher sulfur‐loading cathode without evident cracks in the composite cathode. This achievement can be attributed to the high porosity, excellent wettability, and high conductivity exhibited during an identical electrode preparation procedure. Furthermore, large‐format Li–S pouch cells incorporating MCND/S cathodes are successfully fabricated. These cells demonstrate an energy density surpassing 250 Wh kg−1 and an initial discharge capacity of 3.7 Ah under challenging conditions (S‐loading > 5 mg cm−2 and E/S < 3.5 µL mg−1).

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A Selection Rule for Hydrofluoroether Electrolyte Cosolvent: Establishing a Linear Free‐Energy Relationship in Lithium–Sulfur Batteries

Cited by 41 publications

References 44 publications

Theoretically predicting the feasibility of highly-fluorinated ethers as promising diluents for non-flammable concentrated electrolytes

Theoretically predicting the feasibility of highly-fluorinated ethers as promising diluents for non-flammable concentrated electrolytes

Low‐Density Fluorinated Silane Solvent Enhancing Deep Cycle Lithium–Sulfur Batteries’ Lifetime

Influence of Primary Particle Morphology and Hydrophilicity of Carbon Matrix on Electrode Coating Quality and Performance of Practical High‐Energy‐Density Li–S Batteries

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