High resolution synchrotron X-ray investigation of carbon dioxide evolution in operating direct methanol fuel cells

Hartnig, Christoph; Manke, Ingo; Schloesser, J.; Krüger, Philipp; Kühn, Reimer; Riesemeier, H.; Wippermann, Klaus; Banhart, John

doi:10.1016/j.elecom.2009.05.047

Cited by 56 publications

(22 citation statements)

References 12 publications

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“…In recent years, neutron radiography, [81][82][83][84][85][86][87][88][89][90][91][92][93][94][95] magnetic resonance imaging, [96,97] and X-ray imaging [98][99][100][101][102][103][104][105][106] have been successfully applied to visualize liquid water flow in fuel cells. Magnetic resonance imaging is only suited for very small cells, which must be made of non-metallic materials and contain catalysts with a reduced Pt-load in order to prevent strong image artifacts.…”

Section: Fuel Cellsmentioning

confidence: 99%

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Investigation of Energy‐Relevant Materials with Synchrotron X‐Rays and Neutrons

et al. 2011

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Many materials used for energy conversion have a complex structure and chemical composition, knowledge of which is important for both understanding the function of materials and energy conversion systems and for their further development. Synchrotron radiation and neutrons can make an important contribution to understanding the function of such systems. Taking examples from the fields of fuel cells, gas separation membranes, batteries, solar cells, and catalysts, the use of radiography, tomography, diffraction, scattering, and absorption edge spectroscopy is demonstrated. The strength of such methods is the in situ characterization of processes and compositions, and so the focus is on these aspects.

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Section: Fuel Cellsmentioning

confidence: 99%

“…[101] Figure 5 illustrates a further property of quotient images in that any CO 2 agglomerations in the initial conditions of the experiment are inverted in the quotient image, appearing as bright regions (Fig. 5, white arrow).…”

Section: Direct Methanol Pem Fuel Cell (Dmfc)mentioning

confidence: 99%

Investigation of Energy‐Relevant Materials with Synchrotron X‐Rays and Neutrons

et al. 2011

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“…Recently, neutron and X-ray imaging were shown to be well suited for the investigation of water in porous materials like GDLs. 7,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] As neutron imaging offers large fields of view (typical size 10x10 cm 2 as compared to only several mm 2 in the case of synchrotron X-ray imaging) this technique is especially capable of studying water distribution in larger samples, including complete fuel cells. Typical resolutions for such studies range from 20 to 100 µm.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Carbon Fiber Gas Diffusion Layers by Means of Synchrotron X-ray Tomography

Tötzke¹,

Manke²,

Hartnig³

et al. 2011

ECS Trans.

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The 3-dimensional spatial distribution of liquid water in different gas diffusion layer (GDL) materials was analyzed using synchrotron X-ray tomography. The capability of the method was demonstrated by virtually separating the GDL components in order to facilitate individual analysis of fiber material, liquid water and gas filled pore spaces. The influence of hydrophobic surface treatment on the water distribution in the GDL was illustrated by analyzing three GDL materials with different degrees of hydrophobicity. In the least hydrophobic sample, liquid water tends to form larger clusters which stretch out about several hundred µm inside the porous GDL. In contrast, only small water clusters were found in the strongly hydrophobic material with high Polytetrafluoroethylene (PTFE)-content as the liquid is partially pressed out of the GDL. Additionally, the influence of fiber orientation on the water distribution in the felt material was demonstrated.

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“…Even though DMFCs produce carbon dioxide, which is released into the atmosphere, their high efficiency guarantees low pollution as compared to other power sources. [1][2][3] One drawback of DMFCs is the so-called crossover effect, through which methanol leaves the anodic compartment and crosses the proton exchange membrane (PEM), thereby promoting cell depolarization due to methanol oxidation at the cathode. Hence, it would be interesting to develop PEMs that are able to prevent or Self-Assembled Films from Chitosan and Poly(Vinyl Sulfonic Acid) J. Braz.…”

Section: Introductionmentioning

confidence: 99%

Self-assembled films from chitosan and poly(vinyl sulfonic acid) on Nafion® for direct methanol fuel cell

Vinhola¹,

Facci²,

Dias³

et al. 2012

J. Braz. Chem. Soc.

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Filmes de quitosana/poli(ácido vinilsulfônico) (PVS) foram depositados sobre membranas de Nafion ® a partir do método camada por camada (LbL), visando o seu uso em células a combustível de metanol direto (DMFC). Métodos computacionais e espectros de infravermelho com transformada de Fourier (FTIR) sugerem a formação de um par iônico entre o grupo sulfônico do PVS e o grupo amino protonado da quitosana, o qual promove o crescimento dos filmes LbL sobre a membrana de Nafion ® , assim como impede parcialmente a passagem de metanol. Experimentos de cronopotenciometria e varredura linear de potencial foram realizados a fim de se investigar a passagem de metanol através das membranas de Nafion ® e quitosana/PVS/Nafion ® em uma célula a diafragma. Os valores de resistência iônica associada ao transporte de prótons nas membranas de Nafion ® e quitosana/PVS/Nafion ® são próximos, de acordo com as medidas de impedância elétrica devido à pequena espessura do filme LbL. Assim, espera-se um melhor desempenho da DMFC, uma vez que a resistência do filme automontado é insignificante comparada ao resultado associado à passagem de metanol através das membranas.Chitosan/poly(vinyl sulfonic acid) (PVS) films have been prepared on Nafion ® membranes by the layer-by-layer (LbL) method for use in direct methanol fuel cell (DMFC). Computational methods and Fourier transform infrared (FTIR) spectra suggest that an ionic pair is formed between the sulfonic group of PVS and the protonated amine group of chitosan, thereby promoting the growth of LbL films on the Nafion ® membrane as well as partial blocking of methanol. Chronopotentiometry and potential linear scanning experiments have been carried out for investigation of methanol crossover through the Nafion ® and chitosan/PVS/Nafion ® membranes in a diaphragm diffusion cell. On the basis of electrical impedance measurements, the values of proton resistance of the Nafion ® and chitosan/PVS/Nafion ® membranes are close due to the small thickness of the LbL film. Thus, it is expected an improved DMFC performance once the additional resistance of the self-assembled film is negligible compared to the result associated with the decrease in the crossover effect.Keywords: chitosan, direct methanol fuel cell, proton exchange membrane, crossover effect, methanol permeability IntroductionDirect methanol fuel cells (DMFCs) are the most promising portable, stationary power sources with application in several fields. In these cells, methanol and air are continually injected into the anode and cathode compartments, respectively, thus providing energy with high efficiency. Methanol has been largely employed as fuel once it is abundant and inexpensive. Even though DMFCs produce carbon dioxide, which is released into the atmosphere, their high efficiency guarantees low pollution as compared to other power sources. [1][2][3] One drawback of DMFCs is the so-called crossover effect, through which methanol leaves the anodic compartment and crosses the proton exchange membrane (PEM), thereby promoting cell de...

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High resolution synchrotron X-ray investigation of carbon dioxide evolution in operating direct methanol fuel cells

Cited by 56 publications

References 12 publications

Investigation of Energy‐Relevant Materials with Synchrotron X‐Rays and Neutrons

Investigation of Energy‐Relevant Materials with Synchrotron X‐Rays and Neutrons

Investigation of Carbon Fiber Gas Diffusion Layers by Means of Synchrotron X-ray Tomography

Self-assembled films from chitosan and poly(vinyl sulfonic acid) on Nafion® for direct methanol fuel cell

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