Catalyst layer, method for producing the same, membrane electrode assembly and electrochemical cell

Abstract Micropatterns applied to proton exchange membranes can improve the performance of polymer electrolyte fuel cells; however, the mechanism underlying this improvement is yet to be clarified. In this study, a patterned membrane electrode assembly (MEA) was compared with a flat one using electrochemical impedance spectroscopy and distribution of relaxation time analysis. The micropattern positively affects the oxygen reduction reaction by increasing the reaction area. However, simultaneously, the pattern negatively affects the gas diffusion because it lengthens the average oxygen transport path through the catalyst layer. In addition, the patterned MEA is more vulnerable to flooding, but performs better than the flat MEA in low-humidity conditions. Therefore, the composition, geometry, and operating conditions of the micropatterned MEA should be comprehensively optimized to achieve optimal performance.

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Ex Situ Characterization Method for Flooding in Gas Diffusion Layers and Membrane Electrode Assemblies With a Hydrophilic Gas Diffusion Layer

Journal of Fuel Cell Science and Technology ◽

10.1115/1.4031917 ◽

2015 ◽

Vol 12 (6) ◽

Cited By ~ 2

Author(s):

Toshihiro Tanuma

Keyword(s):

Catalyst Layer ◽

Membrane Electrode Assembly ◽

Gas Diffusion ◽

Dew Point ◽

Water Flooding ◽

Ex Situ ◽

Membrane Electrode ◽

Gas Diffusion Layers ◽

Diffusion Layers ◽

O2 Concentration

Proper water management is required for the operation of polymer electrolyte fuel cells (PEFCs), in order to maintain the critical balance between adequate membrane hydration and prevention of water flooding in the catalyst layer. In PEFCs, the membrane electrode assembly (MEA) is sandwiched between two gas diffusion layers (GDLs). In addition, a microporous layer (MPL) is generally applied to the GDL substrates for better water removal from the cathode catalyst layer. This paper is the first to report on an ex situ characterization method for water flooding in GDLs. As the humidity of O2 gas on the substrate side of the GDL was increased in incremental steps, O2 gas began to diffuse into the MPL side of the GDL. When the O2 relative humidity exceeded the dew point, water flooding was observed on the surface of the MPL and the O2 concentration dropped sharply because the O2 diffusion was suppressed by the produced liquid water. When comparing to the estimated mass transfer loss based on the actual polarization curves of an MEA using the GDL, it was found that the decrease in the O2 concentration on the MPL side of the GDL can be used as an index of water flooding in the PEFC.

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A Novel Structure of Membrane Electrode Assembly for DMFC

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.60-61.339 ◽

2009 ◽

Vol 60-61 ◽

pp. 339-342

Author(s):

Chun Guang Suo ◽

Xiao Wei Liu ◽

Xi Lian Wang

Keyword(s):

Fuel Cell ◽

Direct Methanol Fuel Cell ◽

Catalyst Layer ◽

Membrane Electrode Assembly ◽

Gas Diffusion ◽

Cathode Side ◽

Membrane Electrode ◽

Anode Side ◽

Direct Methanol ◽

Methanol Fuel Cell

Membrane electrode assembly (MEA) is the key component of direct methanol fuel cell (DMFC), the structure and its preparation methods may bring great effects on the cell performances. Due to the requirement of the high performance of the MEA for the micro direct methanol fuel cell (DMFC), we provide a novel double-catalyst layer MEA using CCM-GDE (Catalyst Coated Membrane，CCM；Gas Diffusion Electrode，GDE) fabrication method. The double-catalyst layer is formed with an inner catalyst layer (in anode side: PtRu black as catalyst, in cathode side: Pt black as catalyst) and an outer catalyst layer (in anode side: PtRu/C as catalyst, in cathode side: Pt/C as catalyst). The fabrication procedures are important to the new structured MEA, thus three kinds of fabrication methods are studied, including CCM-GDE, GDE-Membrane and CCM-GDL methods. It was found that the CCM-GDE technology may enhance the contact properties between the catalyst and PEM, and increase the electrode reaction areas, resulted in increasing the performance of the DMFC.

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An Analytical Model of the Membrane Electrode Assembly in a PEMFC

3rd International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2005-74174 ◽

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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