Transient Multiscale Modeling of Aging Mechanisms in a PEFC Cathode

Franco, Alejandro A.; Tembely, Moussa

doi:10.1149/1.2731040

Cited by 117 publications

(162 citation statements)

References 53 publications

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“…The instability of Pt nano-particles for low temperature fuel cell has also been discussed by Shao-Horn et al [24], who presented evidence for different mechanisms including Ostwald ripening, crystal migration, detachment of particle from carbon support and dissolution of Pt in the ion phase. Franco and Tembely [25] proposed a mechanistic model of the electrochemical process for the aging phenomena that take place in PEMFC cathodes. Further fundamental studies and quantitative analysis are however required to improve understanding of the effect of Pt particle size on the CL microstructure.…”

Section: Introductionmentioning

confidence: 99%

Effect of Pt nano-particle size on the microstructure of PEM fuel cell catalyst layers: Insights from molecular dynamics simulations

Cheng

Malek

Sui

2010

Electrochimica Acta

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The effect of Pt nano-particles size on the microstructure of catalyst layers in a Polymer Electrolyte Fuel Cell is investigated by means of molecular dynamics simulations. The catalyst layer model includes carbon-supported platinum, perfluorosulfonate ionomer (PFSI), hydronium ions and water molecules. Three different Pt nano-particle sizes, i.e. 1, 2 and 3 nm, are studied, and simulations provide visualization of the distinct micro-morphologies of the CL corresponding to each nano-particle size. The results are analyzed using pair correlation functions, showing that different microstructures are obtained for different Pt nano-particle sizes, and also that inclusion of PFSI in the simulations impacts significantly the final configuration of Pt nano-particles. Water molecules are found to distribute near the side chains of PFSI and surface of Pt nano-particles, but far from the graphite surface. Side chains form clusters and exhibit different dispersion toward the Pt surface. The orientations of the side chains in the vicinity of the Pt surface are analyzed in detail. The dispersion of perfluorosulfonate ionomer is found to strongly influence the merging of Pt nano-particles and, consequently, the CL microstructure formation.

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Section: Introductionmentioning

confidence: 99%

Effect of Pt nano-particle size on the microstructure of PEM fuel cell catalyst layers: Insights from molecular dynamics simulations

Cheng

Malek

Sui

2010

Electrochimica Acta

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“…A widely accepted mechanism of ORR at platinum electrodes in acidic media was introduced by Damjanovic and Brusic [2] and used by many authors, recently, e.g., Xu et al [7] as well as Franco and Tembely [8]. Quantum mechanical simulations [16] have also reached similar conclusions; however, inherent approximations within those models may not be describing the true complexity of the ORR under electrochemical environments.…”

Section: Model Descriptionmentioning

confidence: 97%

“…The next step is a chemical reaction; however, the exact pathway has not been revealed. The simplest reaction between the adsorbed O 2 H and a water molecule results in adsorbed OH species [8], as shown in Eq. 2.…”

Section: Model Descriptionmentioning

confidence: 99%

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Unusual surface mass changes in the course of the oxygen reduction reaction on platinum and their explanation by using a kinetic model

Kriston

Berkes

Šimon

et al. 2011

J Solid State Electrochem

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An unusual change of the surface mass with time has been observed during the oxygen reduction reaction on Pt using chronopotentiometry and simultaneous electrochemical quartz crystal nanobalance measurements. A simplified kinetic model of Damjanovic and Brusic, which involves two electrochemical and a chemical step, was analyzed using phase plane analysis. The theoretical analysis predicted that bistability might occur in this system at a certain set of parameter values. The mathematical simulation of the different trajectories explained well the strong influence of the starting potential and the current density on the change of the surface mass observed. Evidence was found that the surface coverage can increase at lower potentials, which can lead to the formation of hydrogen peroxide even if it is energetically unfavorable.

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“…It is the multiscale model suggested by Franco et al [36e39]. This multi-scale model combines [36] simulations on different scales: DFT and MD is used for the calculations of the kinetic parameters of the electrochemical reactions, Monte Carlo approach is applied to simulate parameters of Pt catalyst in degraded state and the CFD method is used to predict the fuel cell performance at a certain point of time. However, this model has some shortcomings.…”

Section: Nomenclaturementioning

confidence: 99%

Membrane degradation model for 3D CFD analysis of fuel cell performance as a function of time

Karpenko-Jereb

Sternig

Fink

et al. 2016

International Journal of Hydrogen Energy

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Available online xxxKeywords: Polymer electrolyte fuel cell Nafion degradation Modelling Computational fluid dynamics Local operating condition a b s t r a c t The paper describes a development of a degradation model, which enables to predict timedependent changes in performance of a polymer electrolyte fuel cell. The developed model consists of two main parts: 1) a new semi-empirical model taking into account changes in physico-chemical properties of a polymer electrolyte membrane operating in the fuel cell, 2) a validated CFD model computing the 3D performance of the cell. In the semi-empirical model, the degradation rates of the membrane thickness and conductivity depend on the oxygen crossover rate. The acid group concentration is calculated from the membrane conductivity based on the percolation theory approach. The gas diffusion coefficients are modelled empirically as a function of the membrane thickness. The model of the membrane degradation is coupled with the CFD model and applied to analyse the cell behaviour as a function of time. The simulation shows that the cell current density decreases faster with lowering relative humidity and increasing temperature. The in-plane degradation of the membrane is non-uniform and depends on the local operating condition.

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Transient Multiscale Modeling of Aging Mechanisms in a PEFC Cathode

Cited by 117 publications

References 53 publications

Effect of Pt nano-particle size on the microstructure of PEM fuel cell catalyst layers: Insights from molecular dynamics simulations

Effect of Pt nano-particle size on the microstructure of PEM fuel cell catalyst layers: Insights from molecular dynamics simulations

Unusual surface mass changes in the course of the oxygen reduction reaction on platinum and their explanation by using a kinetic model

Membrane degradation model for 3D CFD analysis of fuel cell performance as a function of time

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