Thickness dependence of water permeation through proton exchange membranes

Adachi, Makoto; Navessin, Titichai; Xie, Zhong; Li, Fei Hua; Tanaka, Shiro; Holdcroft, Steven

doi:10.1016/j.memsci.2010.08.011

Cited by 80 publications

(91 citation statements)

References 41 publications

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“…Finally, possible existence of interfacial effects and "skin" resistances could be important if they exist in AEMs as they are believed to be in PEMs. 27,41,42 Figure 8. Spatial distribution of ionomer water content in the AEM and cCL at 0.6 V for different asymmetric RHs and dominating resistances.…”

Section: Variablementioning

confidence: 99%

Elucidating Performance Limitations in Alkaline-Exchange- Membrane Fuel Cells

Shiau

Zenyuk

Weber

2017

J. Electrochem. Soc.

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Water management is a serious concern for alkaline-exchange-membrane fuel cells (AEMFCs) because water is a reactant in the alkaline oxygen-reduction reaction and hydroxide conduction in alkaline-exchange membranes is highly hydration dependent. In this paper, we develop and use a multiphysics, multiphase model to explore water management in AEMFCs. We demonstrate that the low performance is mostly caused by extremely non-uniform distribution of water in the ionomer phase. A sensitivity analysis of design parameters including humidification strategies, membrane properties, and water transport resistance was undertaken to explore possible optimization strategies. Furthermore, the strategy and issues of reducing bicarbonate/carbonate buildup in the membrane-electrode assembly with CO 2 from air is demonstrated based on the model prediction. Overall, mathematical modeling is used to explore trends and strategies to overcome performance bottlenecks and help enable AEMFC commercialization. Among existing fuel-cell types, alkaline-exchange-membrane fuel cells (AEMFCs) or hydroxide-exchange-membrane fuel cells (HEMFCs) have intriguing features as compared to proton-exchangemembrane fuel cells (PEMFCs). Their advantage is mainly the possibility of using non-noble catalysts due to faster oxygenreduction-reaction (ORR) kinetics in alkaline media than in acidic media 1-4 as well as perhaps the use of less expensive hydrocarbon membranes. Disadvantages of AEMFCs include lower hydrogenoxidation-reaction (HOR) kinetics, more complicated water management, and lower intrinsic conductivity for hydroxide compared to proton transport. [5][6][7][8][9][10][11][12][13] In addition, CO 2 in the air reacts with hydroxide ions to form bicarbonate and carbonate ions, possibly hindering the terrestrial development of AEMFCs by removing hydroxide available for HOR and further limiting hydroxide conductivity. 14,15 Compared to conventional alkaline fuel cells (i.e., using a liquid electrolyte of potassium hydroxide), AEMFCs use a polymeric membrane and should have better tolerance for CO 2 because the precipitate K 2 CO 3 is absent in the AEMFC due to the lack of mobile cations in the membrane. 16 However, AEMFCs still suffer a decline in performance due to bicarbonate/carbonate formation in the membrane and catalyst layers (CLs) leading to additional ohmic and kinetic losses. [13][14][15] In an AEMFC, the following electrochemical reactions occur in the CLs as follows:Net :Hydrogen combines with hydroxide ions to produce water in the anode. Oxygen reacts with water to generate hydroxide ions in the cathode. Along with the transport of ions from cathode to anode, electro-osmosis moves water from cathode to anode. As shown in the reactions, AEMFCs are expected to have more complicated water management. Water production by the HOR and electro-osmosis may cause flooding in the anode. Since water is a stoichiometric reactant at the cathode, dehydration may occur and limit ORR kinetics as well as ionic conduction in the membrane and cathode CL, ...

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Section: Variablementioning

confidence: 99%

Elucidating Performance Limitations in Alkaline-Exchange- Membrane Fuel Cells

Shiau

Zenyuk

Weber

2017

J. Electrochem. Soc.

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“…Water flux (J LLP ) for LLP measurements was recorded using a mass flow meter, while J LVP and J VVP were measured using the gravimetric method. The details of the water permeation experiments are described elsewhere [18,20]. LVP and VVP experiments were performed at 70 C, the relative humidity (RH) ranged between 30 and 90%.…”

Section: Water Permeationmentioning

confidence: 99%

“…Steady-state water permeation in the membrane can be investigated using a permeation cell wherein a membrane is exposed to a chemical-potential gradient induced by a water-activity or pressure gradient [3,10,12,16e20]. Our previous study, using this technique, examined the impact of membrane thickness on water permeation through Nafion membranes and found that water permeation rates, do not increase linearly with decreasing thickness [20]. Other groups have also shown that hydraulic permeation increases with decreasing membrane thickness [22], decreasing equivalent weight (EW) [22] and increasing temperature [16,20,22].…”

Section: Introductionmentioning

confidence: 99%

“…Our previous study, using this technique, examined the impact of membrane thickness on water permeation through Nafion membranes and found that water permeation rates, do not increase linearly with decreasing thickness [20]. Other groups have also shown that hydraulic permeation increases with decreasing membrane thickness [22], decreasing equivalent weight (EW) [22] and increasing temperature [16,20,22]. To date, ex-situ water transport measurements have been exclusively reported for pristine membranes but it is well documented that membranes degrade during fuel cell operation [21,22].…”

Section: Introductionmentioning

confidence: 99%

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Effect of free radical-induced degradation on water permeation through PFSA ionomer membranes

Luo

Ghassemzadeh

Holdcroft

2015

International Journal of Hydrogen Energy

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“…The semi-permeable membranes are used in the LAMEEs to separate the liquid desiccant flow from the air streams and prevent the entrainment of liquid desiccant aerosol into the air streams. Adachi and Alberti in [74,75] respectively show the construction of a counter-flow LAMEE and a schematic of a typical counter-cross-flow RAMEE system. RAMEEs can transfer both heat and moisture by circulating liquid desiccant between LAMEEs in the supply and exhaust airstreams.…”

Section: Run-around Membrane Energy Exchanger (Ramee)mentioning

confidence: 99%