0
Research Papers

Mechanical Degradation Mechanism of Membrane Electrode Assemblies in Buckling Test Under Humidity Cycles

[+] Author and Article Information
Tomoaki Uchiyama

e-mail: tomoaki@uchiyama.tec.toyota.co.jp

Toshihiko Yoshida

Toyota Motor Corporation,
Fuel Cell System Development Div.,
R&D Group 1,
1200, Mishuku, Susono,
Shizuoka 410-1193, Japan

1Corresponding author.

Contributed by the Advanced Energy Systems Division of ASME for publication in the JOURNAL OF FUEL CELL SCIENCE AND TECHNOLOGY. Manuscript received July 30, 2012; final manuscript received September 28, 2012; published online November 16, 2012. Editor: Nigel M. Sammes.

J. Fuel Cell Sci. Technol 9(6), 061005 (Nov 16, 2012) (8 pages) doi:10.1115/1.4007814 History: Received July 30, 2012; Revised September 28, 2012

Membrane electrode assembly (MEA) buckling tests in microscopic clearances under humidity cycles and numerical analyses by finite element method (FEM) were conducted. The NR211 (Dupont, 25-μm thickness, equivalent weight (EW) = 1100) sandwiched between catalyst layers (CLs) was used as the MEA. Based on tensile tests of the NR211 and NR211-CL and FEM simulation of tensile tests, the Young’s modulus and yield point of CL were estimated. While the CL had a higher Young’s modulus than the NR211 in water vapor, the CL indicated a lower Young’s modulus than the NR211 in liquid water at 80 °C. The buckling tests in microscopic diameter of 200 μm in polyimide film were carried out. The heights of bulge in the NR211 and NR211-CL after five humidity cycles were measured with a laser microscope. The height of the NR211-CL was lower than that of the NR211, due to the stiffer CL and the lower swelling ratio of the NR211-CL. Moreover, when the humidity cycles were repeated less than 1000 times, cracks were formed in the CL. The stress-strain behaviors of the NR211-CL buckling test under a humidity cycle were investigated by using the FEM. When the NR211-CL swelled, higher stress was developed at the topside of bulge and topside of bulge round. These portions corresponded to the CL crack-formed portions in the buckling test. When the NR211-CL deswelled, the tensile stress was induced in the entire NR211. The mechanical degradation mechanisms were considered as follows: Firstly, cracks initiate and propagate in the CL when the MEA swells in repeating humidity cycles. Moreover, the tensile stress is induced in the polymer electrolyte membrane (PEM) under deswelling and the CL cracks propagate into the PEM from the CL, which results in pinholes in the PEM.

FIGURES IN THIS ARTICLE
<>
© 2012 by ASME
Your Session has timed out. Please sign back in to continue.

References

Lai, Y. H., and Dillard, D. A., 2009, Handbook of Fuel Cells: Advances in Electrocatalysis, Materials, Diagnostics and Durability, Vol. 5, W.Vielstich, H. A.Gasteiger, and H.Yokokawa, eds., Wiley, New York, pp. 403–419.
Hector, L. G., Jr., Lai, Y. H., Tong, W., and Lukitsch, M. J., 2007, “Strain Accumulation in Polymer Electrolyte Membrane and Membrane Electrode Assembly Materials During a Single Hydration/Dehydration Cycle,” ASME J. Fuel Cell Sci. Technol., 4, pp. 19–28. [CrossRef]
Lai, Y. H., Mittelsteadt, C. K., Gittleman, C. S., and Dillard, D. A., 2009, “Viscoelastic Stress Analysis of Constrained Proton Exchange Membranes Under Humidity Cycling,” ASME J. Fuel Cell Sci. Technol., 6, p. 021002. [CrossRef]
Dillard, D. A., Li, Y., Grohs, J. R., Case, S. W., Ellis, M. W., and Lai, Y. H., Budinski, M. K., and GittlemanC. S., 2009, “On the Use of Pressure-Loaded Blister Tests to Characterize the Strength and Durability of Proton Exchange Membranes,” ASME J. Fuel Cell Sci. Technol., 6, p. 031014. [CrossRef]
Li, Y., Dillard, D. A., Case, S. W., Ellis, M. W., Lai, Y. H., Gittleman, C. S., and MillerD. P., 2009, “Fatigue and Creep to Leak Tests of Proton Exchange Membranes Using Pressure-Loaded Blisters,” J. Power Sources, 194, pp. 873–879. [CrossRef]
Grohs, J. R., Li, Y., Dillard, D. A., Case, S. W., Ellis, M. W., Lai, Y. H., and Gittleman, C. S., 2010, “Evaluating the Time and Temperature Dependent Biaxial Strength of Gore-Select® Series 57 Proton Exchange Membrane Using a Pressure Loaded Blister Test,” J. Power Sources, 195, pp. 527–531. [CrossRef]
Pestrak, M., Li, Y., Case, S. W., Dillard, D. A., Ellis, M. W., Lai, Y. H., and Gittleman, C. S., 2010, “The Effect of Mechanical Fatigue on the Lifetimes of Membrane Electrode Assemblies,” ASME J. Fuel Cell Sci. Technol., 7, p. 041009. [CrossRef]
Tang, Y., Santare, M. H., Karlsson, A. M., Cleghorn, S., and Johnson, W. B., “Stresses in Proton Exchange Membranes Due to Hygro-Thermal Loading,” ASME J. Fuel Cell Sci. Technol., 3, pp. 119–124. [CrossRef]
Kusoglu, A., Karlsson, A. M., Santare, M. H., Cleghorn, S., and Johnson, W. B., 2006, “Mechanical Response of Fuel Cell Membranes Subjected to a Hygro-Thermal Cycle,” J. Power Sources, 161, pp. 987–996. [CrossRef]
Kusoglu, A., Karlsson, A. M., Santare, M. H., Cleghorn, S., and Johnson, W. B., 2007, “Mechanical Behavior of Fuel Cell Membranes Under Humidity Cycles and Effect of Swelling Anisotropy on the Fatigue Stresses,” J. Power Sources, 170, pp. 345–358. [CrossRef]
Kusoglu, A., Santare, M. H., Karlsson, A. M., Cleghorn, S., and Johnson, W. B., 2010, “Numerical Investigation of Mechanical Durability in Polymer Electrolyte Membrane Fuel Cells,” J. Electrochem. Soc., 157(5), pp. B705–B713. [CrossRef]
Solasi, R., Huang, X., Zou, Y., Feshler, M., Reifsnider, K., and Condit, D., 2006, “Mechanical Response of 3-Layered MEA During RH and Temperature Variation Based on Mechanical Properties Measured Under Controlled T and RH,” ASME 4th International Conference on Fuel Cell Science, Engineering and Technology, Irvine, CA, June 19–21, ASME Paper No. FUELCELL2006-97094. [CrossRef]
Huang, X., Solasi, R., Zou, Y., Feshler, M., Reifsnider, K., Condit, D., Burlatsky, S., and Madden, T., 2006, “Mechanical Endurance of Polymer Electrolyte Membrane and PEM Fuel Cell Durability,” J. Polym. Sci., Part B: Polym. Phys., 44, pp. 2346–2357. [CrossRef]
Solasi, R., Zou, Y., Huang, X., Reifsnider, K., and Condit, D., 2007, “On Mechanical Behavior and In-Plane Modeling of Constrained PEM Fuel Cell Membranes Subjected to Hydration and Temperature Cycles,” J. Power Sources, 167, pp. 366–377. [CrossRef]
Aindow, T. T., and O’Neill, J., 2011, “Use of Mechanical Tests to Predict Durability of Polymer Fuel Cell Membranes Under Humidity Cycling,” J. Power Sources, 196, pp. 3851–3854. [CrossRef]
Silberstein, M. N., and Boyce, M. C., 2011, “Hygro-Thermal Mechanical Behavior of Nafion During Constrained Swelling,” J. Power Sources, 196, pp. 3452–3460. [CrossRef]
Uchiyama, T., Kato, M., and Yoshida, T., 2012, “Buckling Deformation of Polymer Electrolyte Membrane and Membrane Electrode Assembly Under Humidity Cycles,” J. Power Sources, 206, pp. 37–46. [CrossRef]
Lai, Y. H., Li, Y., and Rock, J. A., 2010, “A Novel Full-Field Experimental Method to Measure the Local Compressibility of Gas Diffusion Media,” J. Power Sources, 195, pp. 3215–3223. [CrossRef]
Hizir, F. E., Ural, S. O., Kumbur, E. C., and Mench, M. M., 2010, “Characterization of Interfacial Morphology in Polymer Electrolyte Fuel Cells: Micro-Porous Layer and Catalyst Layer Surfaces,” J. Power Sources, 195, pp. 3463–3471. [CrossRef]
Kleemann, J., Finsterwalder, F., and Tillmetz, W., 2009, “Characterisation of Mechanical Behavior and Coupled Electrical Properties of Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers,” J. Power Sources, 190, pp. 92–102. [CrossRef]
Tang, Y., Karlsson, A. M., Santare, M. H., Gilbert, M., Cleghorn, S., and Johnson, W. B., “An Experimental Investigation of Humidity and Temperature Effects on the Mechanical Properties of Perfluorosulfonic Acid Membrane,” Mater. Sci. Eng., A, 425, pp. 297–304. [CrossRef]
Huang, C., Liu, Z. S., and Mu, D. Q., 2008, “The Mechanical Changes in the MEA of PEM Fuel Cells Due to Load Cycling,” ECS Trans., 16(2), pp. 1987–1996. [CrossRef]
Rong, F., Huang, C., Liu, Z. S., Song, D., and Wang, Q., 2008, “Microstructure Changes in the Catalyst Layers of PEM Fuel Cells Induced by Load Cycling—Part I: Mechanical Model,” J. Power Sources, 175, pp. 699–711. [CrossRef]
Poornesh, K. K., Cho, C. D., Lee, G. B., and Tak, Y. S., 2010, “Gradation of Mechanical Properties in Gas Diffusion Electrode—Part 1: Influence of Nano-scale Heterogeneity in Catalyst Layer on Interfacial Strength Between Catalyst Layer and Membrane,” J. Power Sources, 195, pp. 2709–2717. [CrossRef]
Solasi, R., Huang, X., and Reifsnider, K., 2010, “Creep and Stress-Rupture of Nafion® Membranes Under Controlled Environment,” Mech. Mater., 42, pp. 678–685. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

Buckling test of NR211 and NR211-CL under humidity cycles

Grahic Jump Location
Fig. 2

Elastoplastic parameters for materials

Grahic Jump Location
Fig. 3

FEM analysis model for buckling test

Grahic Jump Location
Fig. 4

Humidity change of NR211 in FEM analysis

Grahic Jump Location
Fig. 5

Dimensional changes of NR211 and NR211-CL with relative humidity change

Grahic Jump Location
Fig. 6

Stress-strain curves of NR211 and NR211-CL for (a) 5% RH, (b) 40% RH, (c) 80% RH, (d) 100% RH

Grahic Jump Location
Fig. 7

Bulge deformations of NR211 and NR211-CL by laser microscope observations. (a) NR211 after five cycles and (b) NR211-CL after five cycles.

Grahic Jump Location
Fig. 8

Height of bulge after humidity cycles. Error bar indicates maximum and minimum values.

Grahic Jump Location
Fig. 9

Laser microscope observations for bulge deformations of NR211-CL. (a) After five cycles (height of bulge 3.6 μm), (b) after 1000 cycles (height of bulge 15.6 μm), (c) after 4000 cycles (height of bulge 28.8 μm).

Grahic Jump Location
Fig. 10

Mises stress distributions in NR211 simulation. Comments indicate portion, dominant stress, and Mises stress value. (a) At 50% RH (step 1), (b) at 100% RH (step 2), (c) at 50% RH (step 3), and (d) at 5% RH (step 4).

Grahic Jump Location
Fig. 11

Plastic equivalent strain distribution in NR211 simulation (step 5)

Grahic Jump Location
Fig. 12

Mises stress distributions in NR211-CL simulation. Comments indicate portion, dominant stress, and mises stress value. (a) At 50% RH (step 1), (b) at 100% RH (step 2), (c) at 50% RH (step 3), and (d) at 5% RH (step 4).

Grahic Jump Location
Fig. 13

Plastic equivalent strain distribution in NR211-CL simulation (step 5)

Grahic Jump Location
Fig. 14

Strain behaviors with repeating humidity cycles. (a) True strain in 0–0.4, (b) true strain in 0–0.02, (c) relative humidity change.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In