Ionic diffusion and ion clustering in a perfluorosulfonate ion-exchange membrane

Yeager, H. L.; Kipling, B.

doi:10.1021/j100477a008

Cited by 101 publications

(63 citation statements)

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“…From experimental testing it is seen that this prediction counters the physical data that have been measured for the IPT. To address this discrepancy, the results of Yeager et al 41,42 were used to incorporate the temperature dependent variations in the diffusion coefficient d. These results demonstrated that the changes in d outweighed those of T, causing the high frequency impedance of the model to decrease with temperature, a result that agrees with experimental studies. The series of experimental studies conducted in this research also support and validate the proposed model.…”

Section: Discussionmentioning

confidence: 63%

“…In the temperature study, parameters in the impedance model were tuned to the room temperature response. Then, temperature values were tuned in accordance with experimental conditions and the diffusion coefficient was scaled through previously published results of Yeager et al 41,42 These terms were then applied to the model to predict the response at temperatures above and below the room temperature base line. These results, coupled with those of the diluent and pretension studies, indicate very good correlations between the predicted response and measured data, while also supporting the overall validity of this electrical impedance model of the ionic polymer transducer.…”

Section: Discussionmentioning

confidence: 99%

“…These experiments indicate that the IPT's high frequency resistance actually decreases with a rise in temperature, contrary to the predictions of the model. To account for this discrepancy we revisit our model, incorporating interactions between the ambient temperature T and the diffusion coefficient d. Yeager et al 41,42 conducted several experimental studies that looked at the self-diffusion coefficient of Na + and Cs + through Nafion™ as a function of the ambient temperature. Yeager et al found that the diffusion coefficient had a strong dependence on temperature for each of the counterions considered.…”

Section: Temperature-tmentioning

confidence: 99%

“…Some of the initial work performed in this area was conducted by Yeager et al 41,42 who investigated the selfdiffusion properties of Nafion™ as a function solution temperatures. From their experimental work Yeager et al found that the ion mobility declines with temperature, resulting in lower diffusion coefficients at lower temperature scales.…”

Section: A Impedance As a Function Of Ambient Temperaturementioning

confidence: 99%

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Modeling the electrical impedance response of ionic polymer transducers

Farinholt

Leo

2008

Journal of Applied Physics

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Articles you may be interested inA physics-based model of the electrical impedance of ionic polymer metal composites J. Appl. Phys. 111, 124901 (2012) An analytical study is presented that investigates the electrical impedance response of the ionic polymer transducer. Experimental studies have shown that the electromechanical response of these active materials is highly dependent upon internal parameters such as neutralizing counterion, diluent, electrode treatment, as well as environmental factors such as ambient temperature. Further examination has shown that these variations are introduced predominantly through the polymer's ability to convert voltage into charge migration. This relationship can easily be represented by the polymer's electrical impedance as measured across the outer electrodes of the transducer. In the first half of this study an analytical model is developed which predicts the time and frequency domain characteristics of the electrical response of the ionic polymer transducer. Transport equations serve as the basis for this model, from which a series of relationships are developed to describe internal potential, internal charge density, as well as surface current. In the second half of this study several analytical studies are presented to understand the impact that internal parameters have on the polymer's electrical response, while providing a conceptual validation of the model. In addition to the analytical studies several experimental comparisons are made to further validate the model by examining how well the model predicts changes in temperature, viscosity and pretention within the ionic polymer transducer.

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Section: Discussionmentioning

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Section: Temperature-tmentioning

confidence: 99%

Section: A Impedance As a Function Of Ambient Temperaturementioning

confidence: 99%

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Modeling the electrical impedance response of ionic polymer transducers

Farinholt

Leo

2008

Journal of Applied Physics

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“…[35][36][37][38][39][40] Finally, an average coverage along the channel can be obtained by integration of the local coverage along the length of the channel, 0 < ξ < 1:…”

Section: Modelmentioning

confidence: 99%

An Isothermal Model for Predicting Performance Loss in PEMFCs from Balance of Plant Leachates

Cho

Zee

2014

J. Electrochem. Soc.

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A model is presented for the contamination of a proton exchange membrane fuel cell (PEMFC), including adsorption onto the Pt catalyst, absorption into the membrane, and ion exchange with ionomeric components. Model predictions for three sources of voltage loss account for the two-dimensional, time-dependent contamination along the channel and into the membrane. The model is developed by considering the well-known concepts of Langmuir adsorption, partition coefficients, plug flow reactors (PFRs), and dimensionless analysis. The phenomena are shown to be controlled by three important dimensionless groups: a Damköhler number for the contamination reaction rate, a capacity ratio, and a coverage ratio for each contamination mechanism. These groups show how to scale ex situ equilibrium data for in situ predictions. The model predictions are shown to be reasonable when compared to in situ experiment data once ex situ data are used to provide reaction and equilibrium parameters. The predictions enable estimation of tolerance limits for leachates according to each mechanism. For typical parameters, the predicted voltage loss in the electrode ionomer by an ion-exchange mechanism shows slower reaction rates but greater performance losses than other mechanisms. Analysis of the potential for commercialization of proton exchange membrane fuel cells (PEMFCs) shows that the cost of balance of plant (BOP) materials can be as much as 30% of the system cost.1 One opportunity to decrease these costs is to use off-the-shelf materials rather than custom-made materials, if leachates from less expensive materials would not affect performance and life-time.2 This loss in performance is related to the contamination of the membrane 3 as well as the electrodes. Many previous studies for contamination [3][4][5][6][7][8][9][10][11][12][13] in PEMFCs have shown the sensitivity of performance to low levels of contamination. For example, cation leachates from gaskets or seals, from NH 3 in the fuel, or from catalyst metals 3-9 are well known contaminants of the membrane through an ion-exchange mechanism. Catalyst contamination by CO through an adsorption mechanism from feed gas contaminants is so well-known that those studies are too numerous to list here. Examples are also known for SO 2 , 10,11 for H 2 S, 12 and even for details of the reverse water-gas shift reaction of CO 2 . 13The fundamental mechanism of contamination from organic contaminants such as aniline, ε-caprolactam, and diaminotoluene (DAT), [14][15][16][17][18] which have been identified as possible system contaminants, have been studied only briefly and recently, and it has been shown that their impact on PEMFC performance depends on their functional groups. For example, the ion-exchange reaction of the amine group in aniline with the Nafion membrane/ionomer causes a decrease in the number of available proton sites, thereby hindering the transport of protons and increasing ohmic losses. Aniline is also adsorbed on the carbonsupported platinum catalyst through interactions betw...

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Solute permeation through perfluorocarboxylate membranes

Koyama

Satoh

Iijima

1987

Angew. Makromol. Chem.

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The sorption and permeability of tetraalkylammonium chlorides and alkali chlorides in perfluorocarboxylate membranes were determined. The water content and density of the membranes were found to change with treatment in boiling water and with different tetraalkylammonium cations as counterions for the wboxylate fiied charge. This is attributed to a change in the structure of the membrane matrices. DSC measurements suggested the existence of three distinct phases in the membranes, i.e. a free water phase, a bound water phase, and nonfreezable water. The nonfreezable water was assumed to be in the fluorocarbon phase. The permeability sequence of the tetraalkylammonium chlorides was found to be TEACl > TMACl > TBACl. To interpret the results, a parallel permeation model was proposed. ZUSAMMENFASSUNG:Es wurde die Sorption und Permeabilitilt von Tetraalkylammonium-und Alkalichloriden durch Perfluorwboxylatmembranen bestimmt. Der Wassergehalt und die Dichte der Membranen ilnderten sich durch die Behandlung mit siedendem Wasser und mit verschiedenen Tetraalkylammoniumkationen als Gegenionen fiir die fiierten Carboxylatladungen. Das wird auf eine Vertinderung der Struktur der Membranen zuriickgefiihrt. DSC Messungen weisen auf das Vorhandensein von drei unterschiedlichen Phasen des Wassers in den Membranen hin und zwar das freie Wasser, gebundenes Wasser und nicht gefrierbares Wasser. Das nicht gefrierbare Wasser wird in der Fluorkohlenstoffphase angenommen. Die Reihenfolge der Permeabilitilt der Tetraalkylammoniumchloride ergab sich zu TEACl > TMACl > TBAC1. Zur E r k l h n g der Ergebnisse wurde ein Parallel-Permeation-Modell vorgeschlagen.

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Ionic diffusion and ion clustering in a perfluorosulfonate ion-exchange membrane

Cited by 101 publications

References 1 publication

Modeling the electrical impedance response of ionic polymer transducers

Modeling the electrical impedance response of ionic polymer transducers

An Isothermal Model for Predicting Performance Loss in PEMFCs from Balance of Plant Leachates

Solute permeation through perfluorocarboxylate membranes

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