Fluoroethylene Carbonate as an Electrolyte Additive for Improving the Performance of Mesocarbon Microbead Electrode

Wang, Zhoucheng; Xu, Jie; Yao, Wanhao; Yao, Yiwen; Yang, Yong

doi:10.1149/1.4717960

Cited by 34 publications

(25 citation statements)

References 25 publications

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“…The optimized geometry has a broken bond between atoms C2 and O5, as shown in Figure g. That is also shown in the experiment by Gustafsson and co-workers, and Wang and co-workers, while Nakai and co-workers claimed that the bond between atoms C1 and O6 is broken by reduction . In this study, we found that the C2–O5 broken one is more stable than the C1–O6 broken one by 6.6 kcal/mol (potential energy) and by 6.4 kcal/mol (free energy) in the absence of Li + .…”

Section: Resultssupporting

confidence: 83%

Calculated Reduction Potentials of Electrolyte Species in Lithium–Sulfur Batteries

et al. 2020

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Reduction potentials of electrolyte molecules in the lithium–sulfur (Li/S) battery and their variations in several solvent environments are studied using the density functional theory method with Dunning’s triple-ζ correlation consistent basis set. Reliable reduction potential values are key for electrolyte additive design needed for suppressing polysulfide dissolution shuttle mechanism, resulting in poor cycle performance and severe self-discharge of the Li/S battery. Although isolated electrolyte molecules have reduction potentials outside the operating voltage range of the Li/S battery, complexation with other electrolyte species enables the electrolyte molecules to be reduced within the operating voltage range. Among the electrolyte species considered in this study, bis(fluorosulfonyl)imide (FSI–) and fluoroethylene carbonate (FEC) yield reduction potentials within the expected range, suggesting the development of fluorine-containing additives as a promising line of research.

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Section: Resultssupporting

confidence: 83%

Calculated Reduction Potentials of Electrolyte Species in Lithium–Sulfur Batteries

et al. 2020

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“…Therefore, we can assume that constant surface film formation is prevented, as is FEC consumption. On the other hand, the fact that the VC–EMC ratio in the cycled cell is almost similar to that presented in the case of the pristine electrolyte is in agreement with other studies that report on the suppression of the decomposition of other electrolyte components to a minimum due to the presence of FEC in the electrolyte [ 50 , 54 ]. Hence, a high-rate cycling regime is possible with almost no degradation of the electrolyte.…”

Section: Resultssupporting

confidence: 91%

A Study to Explore the Suitability of LiNi0.8Co0.15Al0.05O2/Silicon@Graphite Cells for High-Power Lithium-Ion Batteries

Cabello

Gucciardi

Liendo

et al. 2021

IJMS

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Silicon–graphite (Si@G) anodes are receiving increasing attention because the incorporation of Si enables lithium-ion batteries to reach higher energy density. However, Si suffers from structure rupture due to huge volume changes (ca. 300%). The main challenge for silicon-based anodes is improving their long-term cyclabilities and enabling their charge at fast rates. In this work, we investigate the performance of Si@G composite anode, containing 30 wt.% Si, coupled with a LiNi0.8Co0.15Al0.05O2 (NCA) cathode in a pouch cell configuration. To the best of our knowledge, this is the first report on an NCA/Si@G pouch cell cycled at the 5C rate that delivers specific capacity values of 87 mAh g−1. Several techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and gas chromatography–mass spectrometry (GC–MS) are used to elucidate whether the electrodes and electrolyte suffer irreversible damage when a high C-rate cycling regime is applied, revealing that, in this case, electrode and electrolyte degradation is negligible.

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“…This trend is generally followed by the fluorinated ethylene carbonates (F-ECs), but not by EC, which shows a bond-breaking mechanism exclusively on Li(110) with the presence of LiPF 6 (Figure d). This discrepancy from the trend can be rationalized by the small reductive potential of EC compared to that of F-ECs (0.6 V versus Li/Li + for EC in mesocarbon microbeads/Li electrodes compared to 1.0 V versus Li/Li + for FEC), which makes EC more responsive to the subtle changes in the coordination environment (or work function) on the Li surface.…”

Section: Discussionmentioning

confidence: 94%

“…FEC degrades more readily on the Li metal surfaces than those conventional base electrolyte solvents, such as EC and diethyl carbonate . The reductive potential of FEC-containing electrolytes is 1.0 V versus Li/Li + compared to 0.6 V versus Li/Li + without FEC (measured in mesocarbon microbeads/Li electrodes with base electrolytes EC/DMC/ethyl methyl carbonate (EMC) 1:1:1 and 1 M LiPF 6 ). Computational studies on the reduction mechanisms involving Si and graphite surfaces , and the reduction within the electrolyte solvent body , are widely available, whereas studies particularly on Li metal surfaces are limited.…”

Section: Resultsmentioning

confidence: 99%

Not All Fluorination Is the Same: Unique Effects of Fluorine Functionalization of Ethylene Carbonate for Tuning Solid-Electrolyte Interphase in Li Metal Batteries

Zhang

Viswanathan

2020

Langmuir

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Li metal batteries (LMBs) are crucial for electrifying transportation and aviation. Engineering electrolytes to form desired solid-electrolyte interphase (SEI) is one of the most promising approaches to enable stable long-lasting LMBs. Among the liquid electrolytes explored, fluoroethylene carbonate (FEC) has seen great success in leading to desirable SEI properties for enabling stable cycling of LMBs. Given the many facets to desirable SEI properties, numerous descriptors and mechanisms have been proposed. To build a detailed mechanistic understanding, we analyze varying degrees of fluorination of the same prototype molecule, chosen to be ethylene carbonate (EC) to tease out the interfacial reactivity at the Li metal/electrolyte. Using density functional theory (DFT) calculations, we study the effect of mono-, di-, tri-, and tetra-fluorine substitutions of EC on its reactivity with Li surface facets in the presence and absence of Li salt. We find that the formation of LiF at the early stage of SEI formation, posited as a desirable SEI component, depends on the F-abstraction mechanism rather than the number of fluorine substitution. The best illustrations of this are cis- and trans-difluoro ECs, where F-abstraction is spontaneous with the trans case, while the cis case needs to overcome a nonzero energy barrier. Using a Pearson correlation map, we find that the extent of initial chemical decomposition quantified by the associated reaction free energy is linearly correlated with the charge transferred from the Li surface and the number of covalent-like bonds formed at the surface. The effect of salt and the surface facet have a much weaker role in determining the decompositions at the immediate electrolyte/electrode interfaces. Putting all of this together, we find that tetra-FEC could act as a high-performing SEI modifier as it leads to a more homogeneous, denser LiF-containing SEI. Using this methodology, future investigations will explore −CF3 functionalization and other backbone molecules (linear carbonates).

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Fluoroethylene Carbonate as an Electrolyte Additive for Improving the Performance of Mesocarbon Microbead Electrode

Cited by 34 publications

References 25 publications

Calculated Reduction Potentials of Electrolyte Species in Lithium–Sulfur Batteries

Calculated Reduction Potentials of Electrolyte Species in Lithium–Sulfur Batteries

A Study to Explore the Suitability of LiNi0.8Co0.15Al0.05O2/Silicon@Graphite Cells for High-Power Lithium-Ion Batteries

Not All Fluorination Is the Same: Unique Effects of Fluorine Functionalization of Ethylene Carbonate for Tuning Solid-Electrolyte Interphase in Li Metal Batteries

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