Magnetic Resonance Imaging of the Water Distribution within a Polymer Electrolyte Membrane in Fuel Cells

Tsushima, Shohji; Teranishi, Kazuhiro; Hirai, Shuichiro

doi:10.1149/1.1774971

Cited by 194 publications

(121 citation statements)

References 13 publications

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“…478,479 These techniques include direct optical imaging of specially designed transparent PEFCs, 480 X-ray radiography 234,240 and tomography, 481 neutron scattering, 482 radiography, 483,484 and tomography, 169 and NMR imaging. 485 For catalyst layers, while recent work has demonstrated that nano X-ray computed tomography can be utilized to measure their pore distribution, 486 it is challenging to obtain the ionomer. 487 Scanning transmission x-ray microscopy (STXM), 488 scanning electron microscopy 331 and other microscopy techniques are being developed to visualize catalyst-layer structures.…”

Section: Intersection With Experimentsmentioning

confidence: 99%

A Critical Review of Modeling Transport Phenomena in Polymer-Electrolyte Fuel Cells

Weber

Borup

Darling³

et al. 2014

J. Electrochem. Soc.

509

394

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Polymer-electrolyte fuel cells are a promising energy-conversion technology. Over the last several decades significant progress has been made in increasing their performance and durability, of which continuum-level modeling of the transport processes has played an integral part. In this review, we examine the state-of-the-art modeling approaches, with a goal of elucidating the knowledge gaps and needs going forward in the field. In particular, the focus is on multiphase flow, especially in terms of understanding interactions at interfaces, and catalyst layers with a focus on the impacts of ionomer thin-films and multiscale phenomena. Overall, we highlight where there is consensus in terms of modeling approaches as well as opportunities for further improvement and clarification, including identification of several critical areas for future research. Fuel cells may become the energy-delivery devices of the 21 st century. Although there are many types of fuel cells, polymer-electrolyte fuel cells (PEFCs) are receiving the most attention for automotive and small stationary applications. In a PEFC, fuel and oxygen are combined electrochemically. If hydrogen is used as the fuel, it oxidizes at the anode releasing proton and electrons according toThe generated protons are transported across the membrane and the electrons across the external circuit. At the cathode catalyst layer, protons and electrons recombine with oxygen to generate waterAlthough the above electrode reactions are written in single step, multiple elementary reaction pathways are possible at each electrode. During the operation of a PEFC, many interrelated and complex phenomena occur. These processes include mass and heat transfer, electrochemical reactions, and ionic and electronic transport. * Electrochemical Society Active Member. z E-mail: azweber@lbl.govOver the last several decades significant progress has been made in increasing PEFC performance and durability. Such progress has been enabled by experiments and computation at multiple scales, with the bulk of the focus being on optimizing and discovering new materials for the membrane-electrode-assembly (MEA), composed of the proton-exchange membrane (PEM), catalyst layers, and diffusionmedia (DM) backing layers. In particular, continuum modeling has been invaluable in providing understanding and insight into processes and phenomena that cannot be resolved or uncoupled through experiments. While modeling of the transport and related phenomena has progressed greatly, there are still some critical areas that need attention. These areas include modeling the catalyst layer and multiphase phenomena in the PEFC porous media.While there have been various reviews over the years of PEFC modeling 1-7 and issues, [8][9][10][11][12][13][14] as well as numerous books and book chapters, there is a need to examine critically the field in terms of what has been done and what needs to be done. This review serves that purpose with a focus on transport modeling of PEFCs. This is not meant to be an exhaustive review...

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Section: Intersection With Experimentsmentioning

confidence: 99%

A Critical Review of Modeling Transport Phenomena in Polymer-Electrolyte Fuel Cells

Weber

Borup

Darling³

et al. 2014

J. Electrochem. Soc.

509

394

View full text Add to dashboard Cite

show abstract

“…Because of the opaque nature of traditional GDL and bipolar plate materials, the investigation and diagnosis of liquid water transport dynamic in an operating PEM fuel cell is a challenging phenomenon using in situ visualization techniques. However, NMR imaging [65][66][67][68][69][70][71][72][73][74][75][76][77][78][79] and beam interrogation techniques, such as neutron imaging , electron microscopy [107][108][109][110], and X-ray techniques [111][112][113][114][115][116], enable the in situ measurement of liquid water distributions in operating PEM fuel cells through materials that would otherwise be opaque to optical access [117]. Using fluorescence microscopy [57,61,118], liquid water can be detected in the through plane direction of the GDL, but limited in depth to several fiber diameters due to the opacity of the material [57].…”

Section: Visualization Of Liquid Water Distributionmentioning

confidence: 99%

“…Tsushima and Teranishi analyzed water transport in PEMFCs [75] as well as water content and distribution in a polymer electrolyte membrane [76][77][78][79]. Similarly, Zhang et al [66] reported a direct water content measurement across the Nafion membrane in an operational PEMFC, employing double half k-space spin echo single point imaging techniques.…”

Section: Nuclear Magnetic Resonance (Nmr) Imagingmentioning

confidence: 99%

A Review of Water Management in Polymer Electrolyte Membrane Fuel Cells

2009

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At present, despite the great advances in polymer electrolyte membrane fuel cell (PEMFC) technology over the past two decades through intensive research and development activities, their large-scale commercialization is still hampered by their higher materials cost and lower reliability and durability. In this review, water management is given special consideration. Water management is of vital importance to achieve maximum performance and durability from PEMFCs. On the one hand, to maintain good proton conductivity, the relative humidity of inlet gases is typically held at a large value to ensure that the membrane remains fully hydrated. On the other hand, the pores of the catalyst layer (CL) and the gas diffusion layer (GDL) are frequently flooded by excessive liquid water, resulting in a higher mass transport resistance. Thus, a subtle equilibrium has to be maintained between membrane drying and liquid water flooding to prevent fuel cell degradation and guarantee a high performance level, which is the essential problem of water management. This paper presents a comprehensive review of the state-of-the-art studies of water management, including the experimental methods and modeling and simulation for the characterization of water management and the water management strategies. As one important aspect of water management, water flooding has been extensively studied during the last two decades. Herein, the causes, detection, effects on cell performance and mitigation strategies of water flooding are overviewed in detail. In the end of the paper the emphasis is given to: (i) the delicate equilibrium of membrane drying vs. water flooding in water management; (ii) determining which phenomenon is principally responsible for the deterioration of the PEMFC performance, the flooding of the porous electrode or the gas

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“…Zhang et al, 2006;Nishida et al, 2010a). Water content distribution in polymer electrolyte membrane (PEM) was measured by using magnetic resonance imaging (MRI) (Tsushima et al, 2004). Although various diagnostic techniques were developed as mentioned above, there are few experimental efforts to measure water distribution inside cathode GDL because of the difficulty in observing internal microstructure of opaque porous layer.…”

Section: Introductionmentioning

confidence: 99%