Electrochemical Reduction of Oxygen in Some Hydrophobic Room-Temperature Molten Salt Systems

Katayama, Yasushi; Onodera, Hokuto; Yamagata, Masaki; Miura, Takashi

doi:10.1149/1.1626669

Cited by 151 publications

(243 citation statements)

References 12 publications

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“…In addition, the diffusion process of hydrogen is not influenced by the apparent viscosity of ILs as presented in Figure 4. This behaviour is consistent with the diffusion of oxygen [13,14] in TFSA-based ILs, because there is almost no electrostatic interaction between the organic ions and the hydrogen or oxygen molecules. We conjecture that the trialkylphosphinebased cations can be assisted by the mass transport of the hydrogen molecule, because the diffusion coefficients of hydrogen in trialkylphosphinebased ILs are relatively larger than those in quaternary phosphonium-based ILs.…”

Section: Diffusion Coefficients Of Hydrogen In Phosphonium-based Ilssupporting

confidence: 83%

Electrochemical Behaviour of Hydrogen in Low-Viscosity Phosphonium Ionic Liquids

Matsumiya

Tsunashima²,

Kodama³

2011

Zeitschrift Für Naturforschung A

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The electrochemical and diffusive properties of hydrogen in low-viscosity phosphonium ionic liquids were investigated by the electrochemical methods such as cyclic voltammetry and chronoamperometry. The hydrogen redox reactions were concluded to be a quasi-reversible system in phosphonium-based ionic liquids. The diffusion coefficients of hydrogen in these ionic liquids were of the order of 10 −10 m 2 s −1 at 25 • C. Additionally, the obtained activation energy of the diffusion process for hydrogen was 11.2 -15.9 kJ mol −1 estimated from the temperature dependence of the diffusion coefficients.A new type of proton conducting medium such as triethylphosphonium bis(trifluoromethylsulfonyl)amide was synthesized by the neutralization reaction, because the trialkylphosphine-based ionic liquids with good stability at higher temperature and high conductivity were appropriate candidates. This proton conducting membrane containing the ionic liquids with trialkylphosphine-based cations and the polyvinylidenefluoride-co-hexafluoropropylene has been fabricated in the present study. The proton conducting membrane exhibits relatively high ionic conductivity along with good mechanical stability.

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Section: Diffusion Coefficients Of Hydrogen In Phosphonium-based Ilssupporting

confidence: 83%

Electrochemical Behaviour of Hydrogen in Low-Viscosity Phosphonium Ionic Liquids

Matsumiya

Tsunashima²,

Kodama³

2011

Zeitschrift Für Naturforschung A

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“…In the pure PP13TFSA system (a), a pair of cathodic and anodic peaks was observed at around ¹1.2 V, which is corresponding to the O 2 redox reaction via one electron reaction process. 12,13,17,19 Although the diffusion limiting process below ¹1.5 V was a little different, the O 2 reduction reaction on three kinds of electrodes was found to be started at almost the same potential. Also, the anodic behaviors during O 2 radical oxidation reaction were almost the same, although the anodic current above 1.0 V caused by decomposition of electrolyte at the carbon edges was slightly obtained in the edge oriented pyrolytic electrode.…”

Section: Electrochemical Behaviors Of Model Electrodes Withmentioning

confidence: 92%

Enhancing Effect of Carbon Surface in the Non-Aqueous Li-O2 Battery Cathode

et al. 2012

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Influence of carbon surface on the discharge voltage of non-aqueous Li-O 2 battery was investigated. The discharge voltage definitely decreased with the graphitization of as-prepared carbon in spite of almost the same chemical information of carbon surface. Graphitization of carbon led to the dramatic morphological change from granulartype to angulated-type, and as a consequence, the number of defect part toward basal part was decreased. The defect parts of the carbon surface were suggested to promote the Li + containing oxygen reduction reaction (Li + -ORR) related with the discharge voltage. Cyclic voltammetry indicated that the ORR potential in the Li + containing media was positively shifted on the edge oriented carbon model plane, compared with those of the graphitized ones. It was, thus, concluded that the carbon surface including defects activated the Li + -ORR process on a cathode, resulting in the increase of discharge voltage.

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“…23, 24 The LiOH could thus originate from the reaction of the electrolyte with superoxide radical, and does not necessarily be a result of the ambient air humidity alone. Recently, we noticed that addition of water helps solubilizing Li 2 O 2 in Li 2 O 2 -prefilled electrodes, which results in a lower initial charging potential.…”

Section: Journal Of the Electrochemical Society 162 (4) A573-a584 (2mentioning

confidence: 99%

The Influence of Water and Protons on Li₂O₂Crystal Growth in Aprotic Li-O₂Cells

Schwenke

Metzger

Restle

et al. 2015

J. Electrochem. Soc.

228

285

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Aprotic Li-O 2 cells have attracted considerable research interest due to its outstandingly high theoretical specific capacity. However, published discharge capacities vary considerably among different researchers despite only minor differences in the tested cell components. Some research groups observe low discharge capacities and formation of passivating layers of Li 2 O 2 on the electronically conducting cathode support, while other groups report large capacities and toroidal Li 2 O 2 crystals as discharge product. In this study we show that these differences may be due to water and protons, both possible impurities in Li-O 2 cells, having a large effect on discharge capacity and Li 2 O 2 morphology. As evidenced by XRD, FTIR and UV-visible analysis, Li 2 O 2 is still the main discharge product in Li-O 2 cells containing water, and moreover the Li 2 O 2 yield increases with the concentration of water in the electrolyte. On-line electrochemical mass spectrometry was employed to understand the differences in the discharge-charge behavior due to the addition of water and protons. While water seems to get oxidized at high potentials during charge, protons are consumed at the beginning of the discharge leading to a variety of reactive oxygen species and thus to degradation of cell components.

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Electrochemical Reduction of Oxygen in Some Hydrophobic Room-Temperature Molten Salt Systems

Cited by 151 publications

References 12 publications

Electrochemical Behaviour of Hydrogen in Low-Viscosity Phosphonium Ionic Liquids

Electrochemical Behaviour of Hydrogen in Low-Viscosity Phosphonium Ionic Liquids

Enhancing Effect of Carbon Surface in the Non-Aqueous Li-O2 Battery Cathode

The Influence of Water and Protons on Li₂O₂Crystal Growth in Aprotic Li-O₂Cells

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Electrochemical Reduction of Oxygen in Some Hydrophobic Room-Temperature Molten Salt Systems

Cited by 151 publications

References 12 publications

Electrochemical Behaviour of Hydrogen in Low-Viscosity Phosphonium Ionic Liquids

Electrochemical Behaviour of Hydrogen in Low-Viscosity Phosphonium Ionic Liquids

Enhancing Effect of Carbon Surface in the Non-Aqueous Li-O2 Battery Cathode

The Influence of Water and Protons on Li2O2Crystal Growth in Aprotic Li-O2Cells

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The Influence of Water and Protons on Li₂O₂Crystal Growth in Aprotic Li-O₂Cells