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

2015 ◽  
Vol 12 (6) ◽  
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.

Stack Compression of PEM Fuel Cells

2004 ◽  
Author(s):  
Yeh-Hung Lai ◽  
Daniel P. Miller ◽  
Chunxin Ji ◽  
Thomas A. Trabold
Keyword(s):  
Fuel Cell ◽  
Membrane Electrode Assembly ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Membrane Electrode ◽  
Gas Diffusion Layers ◽  
Dimensional Changes ◽  
Diffusion Layers ◽  
Wide Range ◽  
Electrolyte Membranes

The effect of dimensional changes of fuel cell components from temperature and hydration cycles on the stack compression is investigated in this paper. Using a simple spring model including the membrane electrode assembly (MEA), gas diffusion layers (GDL), bipolar plates, seal gaskets, current collectors, insulation plates, end plates, and side plates, we find significant compression changes from 30% over-compression to 23% compression loss from both temperature and humidity changes. The wide range of variation in stack compression is attributed to the swelling behavior of polymer electrolyte membranes, the compression behavior of gas diffusion layers, and the design of stack assembly. This paper also reports the use of finite element method to investigate the compression of MEA and GDL over the channel area where MEA buckling from membrane swelling can result in separation of MEA and GDL. It is suggested that the compression over channels can be improved with higher transverse shear modulus in the GDL in addition to the use of narrower channels. In this paper, we will also discuss the challenges facing the fuel cell manufacturers and component suppliers on the needs for new materials with improved mechanical properties and better testing/modeling techniques to help achieving stable compression and better fuel cell stack designs.

scholarly journals Mass Transport Limitations of Water Evaporation in Polymer Electrolyte Fuel Cell Gas Diffusion Layers

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2967
Author(s):  
Adrian Mularczyk ◽  
Andreas Michalski ◽  
Michael Striednig ◽  
Robert Herrendörfer ◽  
Thomas J. Schmidt ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Evaporative Cooling ◽  
Gas Diffusion ◽  
Polymer Electrolyte Fuel Cell ◽  
Ex Situ ◽  
Water Evaporation ◽  
Evaporative Water ◽  
Gas Diffusion Layers ◽  
Diffusion Layers

Facilitating the proper handling of water is one of the main challenges to overcome when trying to improve fuel cell performance. Specifically, enhanced removal of liquid water from the porous gas diffusion layers (GDLs) holds a lot of potential, but has proven to be non-trivial. A main contributor to this removal process is the gaseous transport of water following evaporation inside the GDL or catalyst layer domain. Vapor transport is desired over liquid removal, as the liquid water takes up pore space otherwise available for reactant gas supply to the catalytically active sites and opens up the possibility to remove the waste heat of the cell by evaporative cooling concepts. To better understand evaporative water removal from fuel cells and facilitate the evaporative cooling concept developed at the Paul Scherrer Institute, the effect of gas speed (0.5–10 m/s), temperature (30–60 °C), and evaporation domain (0.8–10 mm) on the evaporation rate of water from a GDL (TGP-H-120, 10 wt% PTFE) has been investigated using an ex situ approach, combined with X-ray tomographic microscopy. An along-the-channel model showed good agreement with the measured values and was used to extrapolate the differential approach to larger domains and to investigate parameter variations that were not covered experimentally.

scholarly journals Gas permeability, wettability and morphology of gas diffusion layers before and after performing a realistic ex-situ compression test

2020 ◽  
Vol 151 ◽  
pp. 1082-1091 ◽  
Author(s):  
F. Aldakheel ◽  
M.S. Ismail ◽  
K.J. Hughes ◽  
D.B. Ingham ◽  
L. Ma ◽  
...  
Keyword(s):  
Compression Test ◽  
Gas Permeability ◽  
Gas Diffusion ◽  
Ex Situ ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
Before And After

Impedance-based Performance Analysis of Micropatterned Polymer Electrolyte Membrane Fuel Cells

2021 ◽  
pp. 1-33
Author(s):  
Morio Tomizawa ◽  
Keisuke Nagato ◽  
Kohei Nagai ◽  
Akihisa Tanaka ◽  
Marcel Heinzmann ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Polymer Electrolyte ◽  
Electrochemical Impedance ◽  
Catalyst Layer ◽  
Membrane Electrode Assembly ◽  
Gas Diffusion ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Membrane Electrode

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.

A Novel Structure of Membrane Electrode Assembly for DMFC

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.

scholarly journals Ex-situ Measurement of Properties of Gas Diffusion Layers of PEM Fuel Cells

2012 ◽  
Vol 29 ◽  
pp. 486-495 ◽  
Author(s):  
Ryan K. Phillips ◽  
Brooks R. Friess ◽  
Anthony D. Hicks ◽  
Julie Bellerive ◽  
Mina Hoorfar
Keyword(s):  
Fuel Cells ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Ex Situ ◽  
Gas Diffusion Layers ◽  
Diffusion Layers

CF4 plasma treatment for preparing gas diffusion layers in membrane electrode assemblies

2006 ◽  
Vol 161 (1) ◽  
pp. 275-281 ◽  
Author(s):  
Yi-Hao Pai ◽  
Jyh-Harng Ke ◽  
Hsin-Fu Huang ◽  
Chih-Ming Lee ◽  
Jyh-Myng Zen ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Gas Diffusion ◽  
Membrane Electrode ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
Membrane Electrode Assemblies ◽  
Electrode Assemblies
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