Parametric Study of Proton-Exchange-Membrane Fuel Cell Cathode Using an Agglomerate Model

Yin, Ken‐Ming

doi:10.1149/1.1854611

Cited by 55 publications

(41 citation statements)

References 28 publications

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“…11,12,14 Since the exact properties and thickness of the film are unknown, a resistance approach (ratio of the film thickness and permeation coefficient) is used to represent the oxygen transport resistance of the film…”

Section: Transportmentioning

confidence: 99%

“…Parametric studies of CLs were accomplished by Yin 14 using an agglomerate model, with the model predicting the general polarization-curve trend as a function of parameters such as gas void fraction 7,16 and ionomer 4,5,10,29 and catalyst loadings 5,10,[30][31][32] within the CL.…”

Section: _enref_29mentioning

confidence: 99%

“…Most CL models using a particle model employ the effectiveness-factor approach for calculating the ORR. 11,13,16,[37][38][39] For a first-order reaction with no other transport limitations, an analytic expression for the effectiveness factor is obtained, 12,14,37 where Φ is the Thiele modulus (11) …”

mentioning

confidence: 99%

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Modeling Low-Platinum-Loading Effects in Fuel-Cell Catalyst Layers

Yoon¹,

Weber²

2011

J. Electrochem. Soc.

145

122

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The cathode catalyst layer within a proton-exchange-membrane fuel cell is the most complex and critical, yet least understood, layer within the cell. The exact method and equations for modeling this layer are still being revised and will be discussed in this paper, including a 0.8 reaction order, existence of Pt oxides, possible non-isopotential agglomerates, and the impact of a film resistance towards oxygen transport. While the former assumptions are relatively straightforward to understand and implement, the latter film resistance is shown to be critically important in explaining increased mass-transport limitations with low Pt-loading catalyst layers. Model results demonstrate agreement with experimental data that the increased oxygen flux and/or diffusion pathway through the film can substantially decrease performance. Also, some scale-up concepts from the agglomerate scale to the more macroscopic porous-electrode scale are discussed and the resulting optimization scenarios investigated. IntroductionThe catalyst layer (CL) is a very complex chemical and geometric environment for electrochemical reactions in proton-exchange-membrane fuel cells (PEMFCs). It is composed of supported catalyst particles, ionomer, and gas pores. The reaction occurs at sites where various reacting species such as protons, electrons, and gases meet. Modeling the structure has been approached by various means 1 , and a rigorous mathematical model of the CL is required to capture transport within the different phases, electrochemical reaction, and heat and water generation. Among previous models, one of the most accepted models is an agglomerate particle composed of the ionomer, gas voids, liquid water, and catalyst that is covered by a thin film of ionomer . This idea is supported by various experimental observations such as scanningelectron-and transmission-electron-microscopy studies. In this model, oxygen is dissolved in the ionomer film surrounding the agglomerate, and the dissolved oxygen diffuses to the agglomerate where simultaneous transport and reaction occur. Typically, the agglomerate model is embedded (i.e., distributed uniformly across the CL) into a porous-electrode model to describe the CL fully 1 . _ENREF_29Optimization of the CL for enhancing PEMFC performance is of great interest for researchers and industry. Parametric studies of CLs were accomplished by Yin 14 using an agglomerate model, with the model predicting the general polarization-curve trend as a function of parameters such as gas void fraction 7,16 and ionomer 4,5,10,29 and catalyst loadings 5,10,[30][31][32] within the CL.Similarly, several optimization studies 16,22,30 using an agglomerate model were conducted to obtain optimum design parameters such as catalyst loading, CL thickness, and Pt/C ratio for best performance at a given potential. However, all the studies were based on several assumptions 4 and issues that are not correct validated or possibly correct including a lack of ionomer films and a first-order oxygen dependence for the oxygen redu...

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Section: Transportmentioning

confidence: 99%

Section: _enref_29mentioning

confidence: 99%

See 1 more Smart Citation

Modeling Low-Platinum-Loading Effects in Fuel-Cell Catalyst Layers

Yoon¹,

Weber²

2011

J. Electrochem. Soc.

145

122

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show abstract

“…In fact, recent studies have clearly shown that treating the cathode CL as an interface with uniform properties leads to several erroneous conclusions, especially due to the impact of channel-rib effects that distribute the electrons, water, heat, and oxygen unevenly at the CL boundary. [115][116][117][118] While an embedded agglomerate model is now utilized in most models, there is still an effort towards including more microstructural details.…”

Section: Catalyst-layer Modelingmentioning

confidence: 99%

Modeling Water Management in Polymer-Electrolyte Fuel Cells

Weber

Balliet

Gunterman

et al. 2008

Modern Aspects of Electrochemistry

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“…The closest approximation to the structure is one of clumps of carbon grains (agglomerates) coated with and connected by electrolyte, [6,[10][11][12][13][14]. A widely employed approach in modelling the CCL is to assume that the agglomerates are spherical in shape, [6,7,[15][16][17][18][19][20], and to incorporate the agglomerate-level activity into a homogeneous model by assuming that a thin film of electrolyte (or water) introduces a local resistance to the oxygen-motivated by the well-established theory of porous catalysts (see Chapter 3 of [21]). The three main variants are as follows:…”

Section: Introductionmentioning

confidence: 99%

The effects of water and microstructure on the performance of polymer electrolyte fuel cells

Shah

Kim

Gervais

et al. 2006

Journal of Power Sources

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In this paper, we present a comprehensive non-isothermal, one-dimensional model of the cathode side of a Polymer Electrolyte Fuel Cell. We explicitly include the catalyst layer, gas diffusion layer and the membrane. The catalyst layer and gas diffusion layer are characterized by several measurable microstructural parameters. We model all three phases of water, with a view to capturing the effect that each has on the performance of the cell. A comparison with experiment is presented, demonstrating excellent agreement, particularly with regard to the effects of water activity in the channels and how it impacts flooding and membrane hydration. We present several results pertaining to the effects of water on the current density (or cell voltage), demonstrating the role of micro-structure, liquid water removal from the channel, water activity, membrane and gas diffusion layer thickness and channel temperature. These results provide an indication of the changes that are required to achieve optimal performance through improved water management and MEA-component design. Moreover, with its level of detail, the model we develop forms an excellent basis for a multi-dimensional model of the entire membrane electrode assembly.

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Parametric Study of Proton-Exchange-Membrane Fuel Cell Cathode Using an Agglomerate Model

Cited by 55 publications

References 28 publications

Modeling Low-Platinum-Loading Effects in Fuel-Cell Catalyst Layers

Modeling Low-Platinum-Loading Effects in Fuel-Cell Catalyst Layers

Modeling Water Management in Polymer-Electrolyte Fuel Cells

The effects of water and microstructure on the performance of polymer electrolyte fuel cells

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