ESR study of dialkyl carbonate radical anions and their thermal and photochemical dissociation in the solid state

Hudson, R. L.; Williams, Ffrançon

doi:10.1021/j150605a012

Cited by 10 publications

(3 citation statements)

References 2 publications

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“…• , and solid state 60 Co γ-irradiation at 77 • K produces methyl and methoxycarbonyl radicals [125,126]. However, to the best of our knowledge, there are no reports on the photolysis or a potential photosensitizing effect of DMC under ambient visible light.…”

Section: Solvent Effectmentioning

confidence: 99%

Mn₂(CO)₁₀‐Visible Light Photomediated, Controlled Radical Polymerization of Main Chain Fluorinated Monomers and Synthesis of Block Copolymers Thereof

Asandei

Adebolu

Simpson

2014

Handbook of Fluoropolymer Science and Technology

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Fluoropolymers constitute a fundamental class of specialty materials endowed with wide morphological versatility, high thermal, chemical, aging, and weather resistance, as well as low surface energy, dielectric constant, flammability, refractive index, and moisture absorption. As such, their applications range from paints and coatings, pipe liners, transmission fluids, O-rings for extreme temperatures, fuel cell membranes, antifouling layers, etc., to optical fibers and high power capacitors [1]. Therefore, their precise synthesis is very relevant.However, while controlled/living radical polymerizations (C/LRPs) have lately undergone remarkable developments [2-6], and atom transfer, nitroxide or additionfragmentation methods [2] have proven quite successful for acrylates or styrenes,

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Section: Solvent Effectmentioning

confidence: 99%

Mn₂(CO)₁₀‐Visible Light Photomediated, Controlled Radical Polymerization of Main Chain Fluorinated Monomers and Synthesis of Block Copolymers Thereof

Asandei

Adebolu

Simpson

2014

Handbook of Fluoropolymer Science and Technology

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“…Alternatively, it abstracts H from the parent compound, yielding yet another H loss radical, in this way initiating a chain reaction. For PC (but not for EC), the radical anion (PC •– ) is stable below 120 K in a glassy frozen matrix. − Ring-opening of the reduced PC also occurs, but it is always concerted with the 1,2-shift . All of these radical intermediates recombine and disproportionate, yielding multiple secondary products and initiating radical and/or anionic polymerization .…”

Section: Introductionmentioning

confidence: 99%

What Makes Fluoroethylene Carbonate Different?

2015

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Rechargeable lithium-ion batteries containing silicon-based negative electrodes have the potential to revolutionize electrical energy storage, but the cyclic and acyclic organic carbonate solvents (such as ethylene and propylene carbonates) that are commonly used in graphite Li-ion batteries, yield unsatisfactory performance when used with such Li alloying electrodes. It has been found by trial-and-error that additions of the closely related carbonate additive, fluoroethylene carbonate (FEC) to conventional electrolytes, yields a robust solid electrolyte interphase (SEI) on the Li x Si y alloy surface.Several mechanisms for this protective action have been considered in the literature and modeled theoretically; however, at present these mechanisms remain hypothetical. In this study, we use radiolysis, laser photoionization, electron paramagnetic resonance, and transient absorption spectroscopy to establish the redox chemistry of FEC. While the oxidation chemistry is similar to that of other organic carbonates, the reduction chemistry of the fluorinated molecule is strikingly different. Specifically, one-electron reduction of bulk FEC causes the fission of two (instead of one) C-O bonds, resulting in concerted defluorination and decarboxylation; in contrast, the reduction of the ethylene and propylene carbonate results in ring-opening and the formation of a radical anion. For FEC, the reduction yields the vinoxyl radical that can abstract an H atom from another FEC molecule, initiating both the chain reaction causing FEC decomposition and radical polymerization involving the reaction products. The resulting polymer can further defluorinate yielding the interior radicals that migrate and recombine to produce a highly cross-linked network. This feature implies that the outer SEI resulting from FEC reduction may exhibit elastomeric properties, which would account for its cohesion during expansion and contraction of silicon particles in the course of Li alloying/dealloying cycling.

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“…The almost identical signal signatures (a g -value tending to 2.0023 and a narrow line width) of EC •– and DMC •– agree well with previous EPR data on glassy cyclic and linear carbonates irradiated at 77 K (details in the Supporting Information). − …”

Section: In Situ Epr Spectroscopy Of Lp30 Electrolytementioning

confidence: 99%

In Situ Electron Paramagnetic Resonance Monitoring of Predegradation Radical Generation in a Lithium Electrolyte

Kukeva,

Kalapsazova,

Rasheev

et al. 2023

J. Phys. Chem. Lett.

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Herein we present an innovative in situ EPR spectroscopy approach complemented with computational modeling as a methodology for assessing a nonaqueous electrolyte behavior just before its massive degradation. As a proof of concept, we use the conventional lithium electrolyte (1 M LiPF6 in EC/DMC), which is utilized in current lithium-ion batteries. Through in situ EPR, long-lived EC•– associates in amounts of 10–250 ppm were detected in a broad potential window (>2.0 V) prior to the electrolyte oxidation or reduction. The pathways of radical formation are discussed in terms of the imperfection in the electron flow across the electrolyte–electrode interface and of the strong affinity of EC to electron trapping. The radical amount could be amplified markedly (above 1000 ppm) by addition of vinylene carbonate (VC) to the electrolyte, while the added CeO2 has a moderate effect. The proposed in situ EPR methodology could be transferred to other electrolyte solutions to become a universal approach.

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ESR study of dialkyl carbonate radical anions and their thermal and photochemical dissociation in the solid state

Cited by 10 publications

References 2 publications

Mn₂(CO)₁₀‐Visible Light Photomediated, Controlled Radical Polymerization of Main Chain Fluorinated Monomers and Synthesis of Block Copolymers Thereof

Mn₂(CO)₁₀‐Visible Light Photomediated, Controlled Radical Polymerization of Main Chain Fluorinated Monomers and Synthesis of Block Copolymers Thereof

What Makes Fluoroethylene Carbonate Different?

In Situ Electron Paramagnetic Resonance Monitoring of Predegradation Radical Generation in a Lithium Electrolyte

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ESR study of dialkyl carbonate radical anions and their thermal and photochemical dissociation in the solid state

Cited by 10 publications

References 2 publications

Mn2(CO)10‐Visible Light Photomediated, Controlled Radical Polymerization of Main Chain Fluorinated Monomers and Synthesis of Block Copolymers Thereof

Mn2(CO)10‐Visible Light Photomediated, Controlled Radical Polymerization of Main Chain Fluorinated Monomers and Synthesis of Block Copolymers Thereof

What Makes Fluoroethylene Carbonate Different?

In Situ Electron Paramagnetic Resonance Monitoring of Predegradation Radical Generation in a Lithium Electrolyte

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Mn₂(CO)₁₀‐Visible Light Photomediated, Controlled Radical Polymerization of Main Chain Fluorinated Monomers and Synthesis of Block Copolymers Thereof

Mn₂(CO)₁₀‐Visible Light Photomediated, Controlled Radical Polymerization of Main Chain Fluorinated Monomers and Synthesis of Block Copolymers Thereof