Impact of synchrotron radiation on fuel cell operation in imaging experiments

Schneider, Armin; Wieser, Christian; Roth, Jörg; Helfen, Lukas

doi:10.1016/j.jpowsour.2010.04.032

Cited by 61 publications

(63 citation statements)

References 19 publications

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“…Between each successive tomogram acquisition was a 120 s rest period during which the X-ray shutter was closed: during this period, the half-cell voltage reverts to the expected decreasing profile. These fluctuating trends in electrochemical behaviour are found to be similar to that previously observed during intermittent X-ray irradiation of TiO 2 film electrodes, where exposure to synchrotron X-rays promoted photoelectrochemical reactions 37 , and also during exposure of low temperature fuel cells to high intensity synchrotron radiation [38][39][40] .…”

Section: Resultssupporting

confidence: 83%

Investigating the evolving microstructure of lithium metal electrodes in 3D using X-ray computed tomography

Taiwo

Finegan

Paz‐Garcia

et al. 2017

Phys. Chem. Chem. Phys.

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The growth of electrodeposited lithium microstructures on metallic lithium electrodes has prevented their use in rechargeable lithium batteries due to early performance degradation and safety implications. Understanding the evolution of lithium microstructures during battery operation is crucial for the development of an effective and safe rechargeable lithium-metal battery. This study employs both synchrotron and laboratory X-ray computed tomography to investigate the morphological evolution of the surface of metallic lithium electrodes during a single cell discharge and over numerous cycles, respectively. The formation of surface pits and the growth of mossy lithium deposits through the separator layer are characterised in threedimensions. This has provided insight into the microstructural evolution of lithium--metal electrodes during rechargeable battery operation, and further understanding of the importance of separator architecture in mitigating lithium dendrite growth.

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Section: Resultssupporting

confidence: 83%

Investigating the evolving microstructure of lithium metal electrodes in 3D using X-ray computed tomography

Taiwo

Finegan

Paz‐Garcia

et al. 2017

Phys. Chem. Chem. Phys.

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“…The catalyzed domain of the MEA was 16 mm 2 (4.5 mm × 3.6 mm) and fitted completely into the X-ray beam during the XTM scans. This was necessary to monitor X-ray induced cell performance degradation 25,34,35 . At the beamline, the cells were operated at 80…”

Section: Methodsmentioning

confidence: 99%

Operando Properties of Gas Diffusion Layers: Saturation and Liquid Permeability

Eller

Roth

Marone

et al. 2016

J. Electrochem. Soc.

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Polymer electrolyte fuel cells (PEFC) require a sophisticated water management to operate efficiently, especially at high current densities which are needed to reach system cost targets. The description of the complicated two-phase water transport remains a challenge in PEFC models and requires experimental validation on various length scales. In this work, operando X-ray tomographic microscopy (XTM) with scan times of 10 s was used to depict the liquid water at defined conditions at a technically relevant cell temperature of 80 • C. Cells with Toray TGP-H-060 gas diffusion layer (GDL) with microporous layer (MPL) and different rib width were operated with different feed gas humidifications (under-and oversaturated) and current densities between 0.75 to 3.0 A/cm 2 . Based on the quantification of the local and average saturation, the distribution of water cluster size is analyzed. Different categories of the water cluster connectivity are defined and quantified. The analysis is complemented with numerical simulations of the permeability in the liquid phase of the GDL that is correlated to saturation for the different GDL domains. The numerical simulations of the pressure drop of liquid water flow from the catalyst layer toward the gas channels in channel-rib repetition units allows for conclusions on cluster growth mechanisms. In the past two decades, large developments have lead hydrogen fed polymer electrolyte fuel cell (PEFC) technology to the brink of commercialization, e.g. in the stationary sector with more than 100000 deployments in the Enefarm activity 1 as well as in the mobile sector where major car manufacturers have presented first commercial vehicles 2,3 and niche-market commercialization for logistic vehicles. 4While for the automotive market also hydrogen infrastructure is a major barrier for widespread application, in both fields of application, cost of the fuel cell system remains the main hindrance for extensive spread of PEFC technology. Cost is closely tied to materials and manufacturing processes, such as more effective electrocatalyst and more durable membrane materials. These developments are underway and have made significant progress. 5 Cost however is also closely tied to power density of the fuel cell stack. It is obvious that with higher power density less cells or an accordingly smaller cell area with the related reduced material use, is leading to a cost reduction if the high power density materials are of comparable cost.Automotive fuel cells with state of the art materials and cell structures reach today more than 1 W/cm 2 with current densities up to 3 A/cm 2 .5 At such high current densities water management becomes more and more important and has to be properly designed on various scales from the system level to nanoscale structures, including all cell components as flow field plates, gas diffusion layers (GDL), the polymer membrane and the catalyst layer (CL). In order to minimize the ohmic losses, the polymer membrane needs to be well humidified, 6 however at high current den...

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“…Synchrotron X-ray radiography offers high spatial and temporal resolutions (less than 10 μm and less than 10 s, respectively) [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]. Though X-ray photons are not as sensitive as a neutron beam to the presence of liquid water, Chevalier et al [29] demonstrated that synchrotron X-ray radiography can achieve similar accuracy to neutron radiography with a high level of precision.…”

Section: Visualizations Of Liquid Water Saturationmentioning

confidence: 99%

Liquid water saturation and oxygen transport resistance in polymer electrolyte membrane fuel cell gas diffusion layers

Muirhead

Banerjee

George

et al. 2018

Electrochimica Acta

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In this thesis, the relative humidity (RH) of the cathode reactant gas was investigated as a factor which influences gas diffusion layer (GDL) liquid water accumulation and mass transport-related efficiency losses over a range of operating current densities in a polymer electrolyte membrane (PEM) fuel cell. Limiting current measurements were used to characterize fuel cell oxygen transport resistance while simultaneous measurements of liquid water accumulation were conducted using synchrotron X-ray radiography. GDL porosity distributions were characterized with micro-computed tomography (μCT). The work presented here can be used by researchers to develop improved numerical models to predict GDL liquid water accumulation and to inform the design of next-generation GDL materials to mitigate mass transport-related efficiency losses. This work also contributes an extensive set of concurrent performance and liquid water visualization data to the PEM fuel cell field that can be used for validating multiphase transport models.iii

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Impact of synchrotron radiation on fuel cell operation in imaging experiments

Cited by 61 publications

References 19 publications

Investigating the evolving microstructure of lithium metal electrodes in 3D using X-ray computed tomography

Investigating the evolving microstructure of lithium metal electrodes in 3D using X-ray computed tomography

Operando Properties of Gas Diffusion Layers: Saturation and Liquid Permeability

Liquid water saturation and oxygen transport resistance in polymer electrolyte membrane fuel cell gas diffusion layers

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