CO[sub 2] Crossover Through a Nafion Membrane in a Direct Methanol Fuel Cell

Jiang, Rongzhong; Chu, Deryn

doi:10.1149/1.1480136

Cited by 52 publications

(39 citation statements)

References 17 publications

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“…This technique uses an optical infrared CO 2 sensor to know the amount of methanol crossing the membrane [17]. It is assumed that the methanol crossing from the anode is completely oxidized to CO 2 on the catalyst layer of the cathode.…”

Section: Introductionmentioning

confidence: 99%

On the Methanol Permeability through Pristine Nafion® and Nafion/PVA Membranes Measured by Different Techniques. A Comparison of Methodologies

et al. 2011

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Methanol crossover through polymer electrolyte membranes is a critical issue and causes an important reduction of performance in direct methanol fuel cells (DMFCs). Measuring the evolution of CO2 gas in the cathode is a common method to determine the methanol crossover under real operating conditions, although an easier and simpler method is preferable for the screening of membranes during their step of development. In this sense, this work has been focused on the ex situ characterization of the methanol permeability in novel nanofiber‐reinforced composite Nafion/PVA membranes for DMFC application by means of three different experimental procedures: (a) potentiometric method, (b) gas chromatography technique, and (c) measuring the density. It was found that all these methods resulted in comparable results and it was observed that the incorporation of the PVA nanofiber phase within the Nafion® matrix causes a remarkable reduction of the methanol permeability. The optimal choice of the most suitable technique depends on the accuracy expected for the methanol concentration, the availability of the required instrumental, and the complexity of the procedure.

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Section: Introductionmentioning

confidence: 99%

On the Methanol Permeability through Pristine Nafion® and Nafion/PVA Membranes Measured by Different Techniques. A Comparison of Methodologies

et al. 2011

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“…The obtained results coincide well with the measured values of methanol crossover currents of Refs. [11][12][13][14]. It is seen in Fig.…”

Section: Modelling Of Dmfc Operationmentioning

confidence: 91%

“…These include methanol and water transport due to concentration gradients across the electrolyte as well as proton conduction and electro osmotic drag, protons moving associated to water and methanol molecules. Much work has been done on characterising the Nafion membrane in a DMFC application with respect to conductivity [5][6][7], methanol uptake and transport [7][8][9][10][11][12][13][14][15][16][17][18][19], and water uptake and transport [14][15][16][17][18][19][20][21][22][23]. Some of the findings of other publications, relevant to this work, are gathered in Table 1.…”

Section: Introductionmentioning

confidence: 99%

A model for mass transport in the electrolyte membrane of a DMFC

Vernersson

Lindbergh

2007

J Appl Electrochem

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A steady state model for multicomponent mass transport was derived for the direct methanol fuel cell membrane. Data for development and validation of the model was taken both from experiments and literature. The experimental data was collected in a polarisation cell, where mass transport of methanol across the electrolyte membrane was measured through a potentiostatic method. The results from modelling and experiments showed good agreement. The model was capable of describing the non-linear response in mass transport to increased methanol feed concentration. The model also accurately described the change in membrane conductivity with methanol concentration. From the model transport equations, it was also possible to derive some characteristic transport parameters, namely the electro osmotic drag of both water and methanol, diffusive drag of water and methanol, and effective, concentration dependent, diffusion coefficients for methanol and water. Keywords Direct methanol fuel cell Á Modelling Á Mass transport Á Methanol crossover Á Electrolyte membrane List of symbols a i Activity of species ''i'' c i Concentration of species ''i'' [mol m -3 ] c T Sum of all concentrations [mol m -3 ] c 1 Concentration of water [mol m -3 ] c 2 Concentration of methanol [mol m -3 ] c 3 Concentration of protons [mol m -3 ] c 4 Concentration of sulphonic acid groups [mol m -3 ] D H 2 O Fickian diffusion coefficient of water [m 2 s -1 ] D CH 3 OH Fickian diffusion coefficient of methanol [m 2 s -1 ] D ij Stefan-Maxwell diffusion coefficient of species ''i'' and ''j'' [m 2 s -1 ] D 12 Stefan-Maxwell diffusion coefficient of water/methanol [m 2 s -1 ] D 13 Stefan-Maxwell diffusion coefficient of water/proton [m 2 s -1 ] D 14 Stefan-Maxwell diffusion coefficient of water/sulphonic acid [m 2 s -1 ] D 23 Stefan-Maxwell diffusion coefficient of methanol/proton [m 2 s -1 ] D 24 Stefan-Maxwell diffusion coefficient of methanol/sulphonic acid [m 2 s -1 ] D 34 Stefan-Maxwell diffusion coefficient of proton/sulphonic acid [m 2 s -1 ] f i Activity factor of species ''i'' [m 3 mol -1 ] F Faraday constant [As mol -1 ] i crossover Methanol crossover current [A m -2 ] i lim Limiting current of methanol crossover [A m -2 ] i load Current density load [A m -2 ] N i Flux of species ''i'' [mol m -1 s -1 ] N 1 Flux of water [mol m -1 s -1 ] N 2 Flux of methanol [mol m -1 s -1 ] N 3 Flux of protons [mol m -1 s -1 ] R Gas constant [J mol -1 K -1 ] T Temperature [K] z i Electric charge of species ''i'' T. Vernersson (

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“…However, during DMFC operation, part of the CO 2 produced at the anode permeates through the membrane to the cathode side. In addition, there is incomplete oxidation of the diffused methanol at the cathode [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of Electrochemical Methods for Determination of Methanol Permeation Through Proton-Exchange Membranes

Zaidi

2011

Arab J Sci Eng

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In this work, methanol permeation rates were measured using various electrochemical techniques, namely, cyclic voltammetry, chronoamperometry and potentiometry. For all the methods, a Nafion ® 117 membrane was used to measure and evaluate methanol crossover rates. The purpose of this study is to compare the methanol permeation data obtained using the above-mentioned techniques under identical conditions, compare the data with the literature data, and then suggest the most accurate and reliable method for the determination of methanol crossover rates. The permeability values using these techniques were found to be in the range 1.11 × 10 −6 to 1.27 × 10 −6 cm 2 /s. The permeability values obtained using these techniques are close to one another and also compare well with the literature data for similar conditions; however, after careful screening of the data, it was found that the potentiometric technique is the easiest in terms of experimentation, reproducibility of results and accuracy, and gives more data points. This technique is suggested to be the best and most accurate for studying methanol permeation rates through membranes for direct methanol fuel cell applications.

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CO[sub 2] Crossover Through a Nafion Membrane in a Direct Methanol Fuel Cell

Cited by 52 publications

References 17 publications

On the Methanol Permeability through Pristine Nafion® and Nafion/PVA Membranes Measured by Different Techniques. A Comparison of Methodologies

On the Methanol Permeability through Pristine Nafion® and Nafion/PVA Membranes Measured by Different Techniques. A Comparison of Methodologies

A model for mass transport in the electrolyte membrane of a DMFC

Comparative Study of Electrochemical Methods for Determination of Methanol Permeation Through Proton-Exchange Membranes

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