Influence of Ammonia on Membrane-Electrode Assemblies in Polymer Electrolyte Fuel Cells

2009 ◽  
Author(s):  
Xiaoyu Zhang ◽  
Joshua Preston ◽  
Ugur Pasaogullari ◽  
Trent Molter
Keyword(s):  
Polymer Electrolyte ◽  
Electrochemical Impedance ◽  
Polymer Electrolyte Membrane ◽  
Catalyst Layer ◽  
Polymer Electrolyte Fuel Cell ◽  
Membrane Electrode ◽  
Electrolyte Membrane ◽  
Catalyst Layers ◽  
Electrode Assemblies ◽  
And Performance

An experimental investigation of contamination of polymer electrolyte fuel cell (PEFC) membranes and catalyst layers with ammonia (NH3) is reported. Cyclic voltammetry (CV) scans and electrochemical impedance spectroscopy (EIS) analyses show that trace amounts of ammonia can significantly contaminate both the polymer electrolyte membrane (PEM) and the catalyst layers. The results show that the catalyst layer contamination can be reversed under certain conditions, while the membrane recovery tends to be much slower, and permanent effects of ammonia contamination is observed. Mechanisms of contamination of the polymer electrolyte and catalyst layers, and performance degradation of the PEFC are also postulated.

The Effect of Ionomer Thin Films in Ionomer- and Water-Filled Agglomerate Models

2011 ◽  
Author(s):  
Peter Dobson ◽  
Marc Secanell
Keyword(s):  
Thin Film ◽  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Numerical Models ◽  
Polymer Electrolyte Membrane ◽  
Catalyst Support ◽  
Catalyst Layer ◽  
Polymer Electrolyte Fuel Cell ◽  
Electrolyte Membrane ◽  
Perfluorosulfonated Ionomer

The catalyst layer of a polymer electrolyte fuel cell is commonly represented in mathematical models as an agglomerate structure of carbon catalyst-support particles. There are two prevailing assumptions for the structure of the agglomerates. The first is that the pores are filled with perfluorosulfonated-ionomer (PFSI). The second is that the pores are hydrophilic and are flooded only with liquid water during operation. The objective of this work is to develop numerical models for single water-filled and ionomer-filled agglomerates in a cathode catalyst layer of a polymer electrolyte membrane fuel cell (PEMFC), and investigate the properties of oxygen transport, proton transport, and reaction kinetics. The two models provide different solutions for the distribution of oxygen and protons, and produce a different reaction profile within the agglomerate. Previous numerical water-filled ionomer models in the literature have neglected the effect of the ionomer thin film. Therefore, the results obtained for both ionomer and water-filled models could not be easily compared. In this article, the equations developed relate the assumed structure of the agglomerates to the structure of the catalyst layer (CL). Results compare the effect of the thin film thickness in the two different types of agglomerates and relate the phenomena occurring within the agglomerates to overall catalyst layer performance.

scholarly journals Electrochemical Impedance Spectroscopy as a Diagnostic Tool in Polymer Electrolyte Membrane Electrolysis

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1368 ◽  
Author(s):  
Stefania Siracusano ◽  
Stefano Trocino ◽  
Nicola Briguglio ◽  
Vincenzo Baglio ◽  
Antonino Aricò
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Polymer Electrolyte ◽  
Diagnostic Tool ◽  
Electrochemical Impedance ◽  
Polymer Electrolyte Membrane ◽  
Membrane Electrode ◽  
Short Side ◽  
Electrolyte Membrane ◽  
The Impact

Membrane–electrode assemblies (MEAs) designed for a polymer electrolyte membrane (PEM) water electrolyser based on a short-side chain (SSC) perfluorosulfonic acid (PFSA) membrane, Aquivion®, and an advanced Ir-Ru oxide anode electro-catalyst, with various cathode and anode noble metal loadings, were investigated. Electrochemical impedance spectroscopy (EIS), in combination with performance and durability tests, provided useful information to identify rate-determining steps and to quantify the impact of the different phenomena on the electrolysis efficiency and stability characteristics as a function of the MEA properties. This technique appears to be a useful diagnostic tool to individuate different phenomena and to quantify their effect on the performance and degradation of PEM electrolysis cells.

An Analytical Model of the Membrane Electrode Assembly in a PEMFC

2005 ◽  
Author(s):  
S. Litster ◽  
N. Djilali
Keyword(s):  
Fuel Cells ◽  
Analytical Model ◽  
Polymer Electrolyte Membrane ◽  
Finite Thickness ◽  
Catalyst Layer ◽  
Ambient Air ◽  
Membrane Electrode Assembly ◽  
Membrane Electrode ◽  
Electrolyte Membrane ◽  
Catalyst Layers

An analytical model of the membrane electrode assembly (MEA) in a polymer electrolyte membrane fuel cell (PEM) has been developed for investigating the effect of catalyst layer specifications. Emphasis is placed on the cathode catalyst layer, which is modeled using a finite-thickness formulation with parameters obtained from a variable-width macrohomogeneous model. The variable-width formulation accounts for the effect of changing catalyst layer specifications on the dimensions of the catalyst layer by assuming a constant void fraction. Interest in low-humidity operation of micro-fuel cells that are passively fed ambient air has facilitated the present derivations and assumptions. The model is shown to agree well with experimental data over a substantial range of catalyst layer specifications. In addition, the model shows excellent promise as a tool for optimizing catalyst layers in micro-fuel cells with passive ambient air breathing.

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