Effect of conditioning techniques of perfluorinated sulphocationic membranes on their hydrophylic and electrotransport properties

Березина, Н. П.; Тимофеев, С. В.; Kononenko, N. A.

doi:10.1016/s0376-7388(02)00368-x

Cited by 135 publications

(62 citation statements)

References 14 publications

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“…The hydration number ranges between 4 and 17 mol water per mol of sulphonic group, which is in agreement with the chemical structure reported in the relevant literature (Berezina et al, 2002).…”

Section: Volume Variations and Swelling Pressuressupporting

confidence: 90%

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Swelling behavior of PEMFC during conditioning

Parrondo

Ortueta

Mijangos

2007

Braz. J. Chem. Eng.

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-Polymeric cation exchange membranes (PEMFC) are used in fuel cell technology. These membranes act as a physical barrier between anode and cathode, but diffusion through the membrane should allow protons to be carried from anode to cathode at a rate sufficient to supply energy requirements. They avoid any direct reaction of oxygen and hydrogen that would diminish fuel cell efficiency. Membranes have to be conditioned before use. This conditioning step changes membrane counterions and modifies their water content, which has an effect on their diffusion coefficients. In order to analyse and quantify the effect of conditioning techniques on membrane performance various experiments with Nafion 117 cation exchange membranes were carried out. Membranes were conditioned using various methods to change the charged cation in the membrane. The reactives used were ultrapure water, nitric acid, hydrochloric acid, hydrogen peroxide, sodium chloride, potassium chloride and ethylene glycol, all at room temperature. Some conditioning methods were carried out using solvents heated to 100 ºC. Water content was indirectly monitored by measuring membrane swelling. Results show that membrane conditioning with strong acids followed by treatment with water increases membrane water content by about 5%. Using high-temperature treatment the water content also increases. Water uptake or release from membranes is analysed in terms of water activity.

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Section: Volume Variations and Swelling Pressuressupporting

confidence: 90%

“…These membranes can be found in different states, classified by Berezina et al (2002) as normal, shrunk and extended: "normal" is the typical state for the end product; the shrunk state is achieved after boiling in salt solutions and finally the extended state is achieved after sequential boiling steps in acids and distilled water.…”

Section: Introductionmentioning

confidence: 99%

Swelling behavior of PEMFC during conditioning

Parrondo

Ortueta

Mijangos

2007

Braz. J. Chem. Eng.

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“…The transport properties of Nafion are significantly altered by treatments and processing done after manufacturing. [43][44][45][46] Sun et al 17 did not report how they treated their membranes, but the common approach of immersion in boiling water or acid causes Nafion to expand and increases transport properties relative to asreceived membranes. This is probably why the diffusion coefficients that fit the data are smaller than those in Table I.…”

Section: Resultsmentioning

confidence: 99%

The Influence of Electric Field on Crossover in Redox-Flow Batteries

Darling

Weber

Tucker

et al. 2015

J. Electrochem. Soc.

152

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Transport of active species through the ion-exchange membrane separating the electrodes in a redox-flow battery is an important source of inefficiency. Migration and electro-osmosis have significant impacts on the crossover of reactive anions, cations, and neutral species. In this paper, these phenomena are theoretically and experimentally explored for commercial cation-exchange membranes. The theoretical analysis indicates that plotting the cumulative Coulombic mismatch between charge and discharge as a function of time can be used to assess crossover rates. The relative importance of migration and electro-osmosis over diffusion is quantified and shown to increase with increasing current density and membrane thickness because the contributions of migration and electro-osmosis to ionic flux are independent of membrane thickness and proportional to current density, while diffusion is inversely proportional to membrane thickness and independent of current density. Redox-flow batteries (RFBs) possess compelling attributes for stationary energy storage. In particular, the inherent decoupling of energy and power in RFBs enables the cost effective use of active materials with low energy density.1,2 Energy is stored in redox-active molecules and power is generated by oxidizing and reducing different redox couples at the positive and negative electrodes.3-5 Two promising technologies are the all-vanadium RFB (VRB) and the hydrogen/bromine RFB, where good performances have been demonstrated recently. [6][7][8][9][10][11][12][13][14] Protons in a cation-exchange membrane (CEM) typically carry charge between the two electrodes in these two RFBs. In both systems, movement of reactant or product species from one electrode to the other through the membrane results in inefficiency and reversible capacity loss. 8,15,16 For these reasons it is worthwhile to investigate the causes of crossover, and examination of the two chosen RFBs allows for the study of transport of active cations, anions, and neutral species.The reactions at the negative and positive electrodes in a VRB are:andrespectively. Protons are the primary ionic charge carriers. Because the active species at both electrodes are vanadium ions, transfer from one electrode to the other is less detrimental than it is in other RFBs that have dissimilar active materials at the two electrodes. Vanadium that traverses the separator reacts to form a discharged ion at the opposite electrode. 17 Although imbalances that occur after repeated cycling can be recovered by mixing the electrolytes, vanadium that crosses the membrane represents an inefficiency that is detrimental in applications like grid-scale energy storage where high efficiency is required for economic success.For the hydrogen/bromine RFB, the reactions at the negative and positive electrodes areBr 2 (aq) + 2e 18-21 Br species that enter the negative electrode can be separated from the negative electrolyte and returned to the positive electrolyte without causing permanent decay, in a similar fashion to vanadium in V...

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“…In this context, it should be pointed out the significant number of papers published in recent years dealing with original and modified proton-exchange membranes conductivity and permeability, which are considered key parameters for their applications in proton and methanol (DMFCs) fuel cells, respectively [16][17][18][19][20][21][22]; particularly, a reduction of around two orders of magnitude in the methanol permeability across Nafion/IL-modified membranes attributed to the decrease of the methanol crossover associated to the presence of the ILcation has already been reported [23]. However, a more reduced number of papers on surface study of both original and modified membranes are published, although membrane surface represents the interface between two different transport media, which can be solid/solid in the case of fuel cells or solid/liquid when supported liquid membranes (SLMs) or other electrochemical devices proposed for selective solute separation are considered [15,24,25].…”

Section: Introductionmentioning

confidence: 99%

Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

Romero

Yuso

Arango

et al. 2012

International Journal of Electrochemistry

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Bulk and surface changes in two proton-exchange membranes (Nafion-112 and Nafion-117) as a result of the incorporation of the IL-cation n-dodecyltriethylammonium (or DTA + ) by a proton/cation exchange mechanism after immersion in a DTA + aqueous solution were analysed by impedance spectroscopy (IS), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), and contact angle measurements performed with dry samples of the original Nafion and Nafion-DTA + -modified membranes. Only slight differences were obtained in the incorporation degree and surface chemical nature depending on the membrane thickness, and DTA + incorporation modified both the hydrophobic character of the original Nafion membranes and their thermal stability. Electrical characterization of the dry Nafion-112 membrane was performed by impedance spectroscopy while different HCl solutions were used for membrane potential measurements. A study of time evolution of the impedance curves measured in the system "IL aqueous solution/Nafion-112 membrane/IL aqueous solution" was also performed. This study allows us monitoring the electrical changes associated to the IL-cation incorporation in both the membrane and the membrane/IL solution interface, and it provides supplementary information on the characteristic of the Nafion/DTA + hybrid material. Moreover, the results also show the significant effect of water on the electrical resistance of the Nafion-112/IL-cation-modified membrane.

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Effect of conditioning techniques of perfluorinated sulphocationic membranes on their hydrophylic and electrotransport properties

Cited by 135 publications

References 14 publications

Swelling behavior of PEMFC during conditioning

Swelling behavior of PEMFC during conditioning

The Influence of Electric Field on Crossover in Redox-Flow Batteries

Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

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