Mechanical endurance of polymer electrolyte membrane and PEM fuel cell durability

Huang, Xinyu; Solasi, Roham; Zou, Yue; Feshler, Matthew; Reifsnider, Kenneth L.; Condit, David; Burlatsky, S. F.; Madden, T.

doi:10.1002/polb.20863

Cited by 321 publications

(255 citation statements)

References 36 publications

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“…3,18,25 However, because AEM development is still preliminary, basic mechanical testing is not standardized and comparing mechanical properties of AEMs is difficult. In this study, the extensional properties of three well-studied AEMs were investigated under different temperature and humidity conditions.…”

Section: H678mentioning

confidence: 99%

“…Thorough studies have been performed on the mechanical strength, durability, and failure mechanisms of PEMs, 3,6,18 and this information can be used to guide AEM development and testing. Ex-situ durability tests to gauge membrane lifetime of PEMs include rapid humidity cycling while monitoring gas crossover, 19 pressurized blister tests, 20 and mechanical fatigue testing by dynamic mechanical analysis.…”

Section: -11mentioning

confidence: 99%

“…17 Decoupling the effects of chemical and mechanical degradation is difficult in in-situ fuel cell tests, particularly over the short time-span of traditional testing, making it critical to develop ex-situ, accelerated test methods to gauge mechanical degradation. Thorough studies have been performed on the mechanical strength, durability, and failure mechanisms of PEMs, 3,6,18 and this information can be used to guide AEM development and testing. Ex-situ durability tests to gauge membrane lifetime of PEMs include rapid humidity cycling while monitoring gas crossover, 19 pressurized blister tests, 20 and mechanical fatigue testing by dynamic mechanical analysis.…”

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Mechanical Characterization of Anion Exchange Membranes by Extensional Rheology under Controlled Hydration

Vandiver

Caire

Carver

et al. 2014

J. Electrochem. Soc.

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Alkali anion exchange membrane (AEM) based devices have the potential for electrochemical energy conversion using inexpensive catalysts and a variety of fuel types. Membrane stability and anion transport must be improved in AEMs before these devices can be fully realized. Mechanical failure of the membrane can contribute to failure of the device, thus membrane durability is critical to overall system design. Here, a study of the mechanical properties of three well-established AEMs uses a modified extensional rheometer platform to simulate tensile testing using small membrane samples. Mechanical properties were tested at 30 and 60 • C under dry or water saturated gas conditions. Water in the membrane has a plasticizing effect, softening the membrane and reducing strength. PEEK membrane reinforcement limits swelling producing negligible softening and only a 9% decrease in strength from dry to hydrated conditions at 30 • C. Higher cation concentration increases water uptake resulting in significant softening, a 57% reduction in Young's modulus, and a 67% reduction in strength when hydrated at 30 • C. In a working electrochemical device, AEMs must maintain integrity over a range of temperatures and hydrations, making it critical to considering mechanical properties when designing new membranes. Polymer electrolyte membrane fuel cells and electrolyzers are potentially disruptive technologies that will replace traditional heat engines such as internal combustion engines for transportation applications, portable electronics, and are scalable to larger energy storage facilities. Polymer electrolyte membrane fuel cells are suitable for transportation applications due to their low temperature start-up and operation, high power density, and quick refueling.1-3 Proton exchange membranes (PEMs) have dominated polymer electrolyte membrane fuel cell development in the last several decades, resulting in the development of relatively stable, well performing membranes.1-4 Current PEM fuel cells remain cost prohibitive due to high catalysts costs, as well as long-term durability issues. 3,5,6 Anion exchange membranes (AEMs) can also be utilized in polymer electrolyte membrane devices and have several potential benefits over PEMs. AEM fuel cells benefit from increased kinetics in an alkali media allowing more complex fuels then hydrogen and have the potential to utilize non-platinum catalysts to reduce costs. 7-11However, a number of challenges must be overcome before AEMs reach the performance and durability necessary for fuel cells and other electrochemical energy conversion devices. Hydroxide present in the AEM degrades many of the proposed cationic groups and some polymer backbones, making development of chemically stable AEMs difficult. 9,11,12 Additionally, transport of hydroxide in AEMs is inherently slower than protons in PEMs, 13 to compensate, the concentration of ionic groups is often increased in AEMs.8 Increasing ion concentration in AEMs increases water sorption in the polymer and can result in significant dimensional...

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Section: H678mentioning

confidence: 99%

Section: -11mentioning

confidence: 99%

mentioning

confidence: 99%

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Mechanical Characterization of Anion Exchange Membranes by Extensional Rheology under Controlled Hydration

Vandiver

Caire

Carver

et al. 2014

J. Electrochem. Soc.

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Section: I: Introductionmentioning

confidence: 99%

“…Operation of a fuel cell under realistic load cycles results in both chemical and mechanical degradation of the polymer electrolyte membrane. Degradation of the membrane causes opening up of pinholes or crazing of polymer [1,2,7] increasing gas-crossover and subsequently resulting in catastrophic failures of the fuel cell stack.Understanding and modeling the mechanical degradation mechanism and kinetics enables prediction of membrane lifetime as a function of PEM operational conditions and optimization of membrane structure through the choice of reinforcement [4], the membrane processing methods and the operating conditions. The physics based model of membrane mechanical degradation could guide the synthesis of new membranes with tuned mechanical properties and enhanced life in a fuel cell.…”

mentioning

confidence: 99%

A mathematical model for predicting the life of polymer electrolyte fuel cell membranes subjected to hydration cycling

Burlatsky¹,

Gummalla²,

O'Neill³

et al. 2012

Journal of Power Sources

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Under typical PEM fuel cell operating conditions, part of membrane electrode assembly is subjected to humidity cycling due to variation of inlet gas RH and/or flow rate. Cyclic membrane hydration/dehydration would cause cyclic swelling/shrinking of the unconstrained membrane. In a constrained membrane, it causes cyclic stress resulting in mechanical failure in the area adjacent to the gas inlet. A mathematical modeling framework for prediction of the lifetime of a PEM FC membrane subjected to hydration cycling is developed in this paper. The model predicts membrane lifetime as a function of RH cycling amplitude and membrane mechanical properties. The modeling framework consists of three model components: a fuel cell RH distribution model, a 2 hydration/dehydration induced stress model that predicts stress distribution in the membrane, and a damage accrual model that predicts membrane life-time. Short descriptions of the model components along with overall framework are presented in the paper. The model was used for lifetime prediction of a GORE-SELECT membrane. I: Introduction:Mechanical degradation of PEM membrane can limit stack lifetime. Operation of a fuel cell under realistic load cycles results in both chemical and mechanical degradation of the polymer electrolyte membrane. Degradation of the membrane causes opening up of pinholes or crazing of polymer [1,2,7] increasing gas-crossover and subsequently resulting in catastrophic failures of the fuel cell stack.Understanding and modeling the mechanical degradation mechanism and kinetics enables prediction of membrane lifetime as a function of PEM operational conditions and optimization of membrane structure through the choice of reinforcement [4], the membrane processing methods and the operating conditions. The physics based model of membrane mechanical degradation could guide the synthesis of new membranes with tuned mechanical properties and enhanced life in a fuel cell.Hydration cycling is a primary cause of the mechanical degradation of a geometrically constrained polymer, which exhibits dimensional changes with varied water content. A simple way to impose mechanical damage to a geometrically constrained PEM membrane is to subject it to humidity cycling. At high RH, the membrane absorbs water, and at low RH, the membrane desorbs water. Such RH cycling would result in swelling 3 and shrinking of an unconstrained polymer. RH cycling of a constrained polymer causes cyclic stress. In PEM, such geometrical constraints are imposed by bipolar plate ribs through the gas diffusion layers (GDLs), catalyst layers adjacent to the membrane and at the seals. Moreover, we hypothesize that internal stress in the membrane can be caused by the difference in gas RH at the anode and cathode membrane surfaces that routinely occurs at fuel cell operational conditions. Cyclic stress in the membrane causes irreversible elongation of the membrane [7] and subsequent formation of crazes and cracks that causes gas crossover through the membrane and stack failure.The goal of...

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Mechanical durability characterization and modeling of ionomeric membranes

Lai

Dillard

2010

Handbook of Fuel Cells

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Many of the premature failures in proton exchange membrane (PEM) fuel cells are attributed to the crossover of reactant gases through cracks developing in the membrane during fuel cell operation. Postmortem analysis of membranes subjected to fuel cell humidity cycling tests in the absence of electrochemical reaction suggests that membrane cracks are driven by the in‐plane tensile stress state that develop within the membrane during cyclic hygrothermal loading. This article presents an effort to develop a suite of analytical and experimental methods within a framework of viscoelasticity to characterize the mechanical stresses, constitutive properties, strength, and durability/lifetime of proton exchange membranes. The success obtained in accounting for a range of observed phenomena suggests the applicability and usefulness of this framework.

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Mechanical endurance of polymer electrolyte membrane and PEM fuel cell durability

Cited by 321 publications

References 36 publications

Mechanical Characterization of Anion Exchange Membranes by Extensional Rheology under Controlled Hydration

Mechanical Characterization of Anion Exchange Membranes by Extensional Rheology under Controlled Hydration

A mathematical model for predicting the life of polymer electrolyte fuel cell membranes subjected to hydration cycling

Mechanical durability characterization and modeling of ionomeric membranes

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