Modeling and Experimental Diagnostics in Polymer Electrolyte Fuel Cells

Abstract

This paper presents a fit between model and experiment for well‐humidified polymer electrolyte fuel cells operated to maximum current density with a range of cathode gas compositions. The model considers, in detail, losses caused by: (i) interfacial kinetics at the Pt/ionomer interface, (ii) gas‐transport and ionic‐conductivity limitations in the catalyst layer, and (iii) gas‐transport limitations in the cathode backing. Our experimental data were collected with cells that utilized thin‐film catalyst layers bonded directly to the membrane, and a separate catalyst‐free hydrophobic backing layer. This structure allows a clearer resolution of the processes taking place in each of these distinguishable parts of the cathode. In our final comparison of model predictions with the experimental data, we stress the simultaneous fit of a family of complete polarization curves obtained for gas compositions ranging from 5 atm O2 to a mixture of 5% O2 in N2 , employing in each case the same model parameters for interfacial kinetics, catalyst‐layer transport, and backing‐layer transport. This approach allowed us to evaluate losses in the cathode backing and in the cathode catalyst layer, and thus identify the improvements required to enhance the performance of air cathodes in polymer electrolyte fuel cells. Finally, we show that effects of graded depletion in oxygen along the gas flow channel can be accurately modeled using a uniform effective oxygen concentration in the flow channel, equal to the average of inlet and exit concentrations. This approach has enabled simplified and accurate consideration of oxygen utilization effects.

Effects of porosity change of gas diffuser on performance of proton exchange membrane fuel cell

“…Models to describe the steady-state performance of the PEM fuel cell have been developed by other workers [1,10,[22][23][24]. The complexity of the model varies considerably.…”

“…Bernardi and Verbrugge [7] employed gas-phase transport and membrane models to investigate the performance of a gas-fed porous cathode bonded to a polymer electrolyte, and later they developed a one-dimensional isothermal model for the cell [8]. Springer et al [9,10] also derived an isothermal, one-dimensional, steady-state model of a PEM fuel cell to simulate performance with a partially dehydrated membrane. Following the work of Bernardi and Verbrugge [8], Singh et al [11] developed a two-dimensional isothermal model to investigate the effect of two-dimensionality on fuel cell performance.…”

Optimization of fuel cell system operating conditions for fuel cell vehicles

“…Fuel cell models at the cell level are presented in [2][3][4]. Studies concerned with optimum operating conditions are discussed in [5][6][7][8][9][10][11][12].…”

Numerical Simulation of Electrochemical Processes in Polymeric Membrane Fuel Cells

“…Extensive researches have been carried out to simulate the fuel cells. For instance, Bernardi and Verbrugge [1,2], and Sourceer et al [3,4] built one-dimensional models. Fuller and Newman [5], Nguyen and White [6], Gurau et al [7], and Yi and Nguyen [8,9] presented similar pseudo twodimensional models which were actually the models along the fluid path.…”