A review of polymer electrolyte membrane fuel cell durability test protocols

Yuan, Xiao‐Zi; Li, Hui; Zhang, Shengsheng; Martin, Jonathan; Wang, Haijiang

doi:10.1016/j.jpowsour.2011.07.082

Cited by 291 publications

(136 citation statements)

References 78 publications

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“…There are several cyclical, hygro-thermal accelerated aging tests, which are used to assess the mechanical durability of membranes in the absence of electrochemical activity [2,10]. These test proto cols provide a basis for comparison of the purely mechanical behavior of different membrane material compositions and designs.…”

Section: Introductionmentioning

confidence: 99%

Effect of time-dependent material properties on the mechanical behavior of PFSA membranes subjected to humidity cycling

Khattra

Karlsson

Santare

et al. 2012

Journal of Power Sources

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Section: Introductionmentioning

confidence: 99%

Effect of time-dependent material properties on the mechanical behavior of PFSA membranes subjected to humidity cycling

Khattra

Karlsson

Santare

et al. 2012

Journal of Power Sources

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“…18 Following this recent study, in this work the durability of Pt 3 Ni aerogels in the PEFC is investigated for two different accelerated stress tests (ASTs) proposed by the DOE and compared to a commercial Pt/C benchmark. The first AST exposes the catalyst to the potential regime of 1.0 to 1.5 V RHE , which can occur in an operating PEFC during fuel starvation and start-up/shut-down of the cell and triggers C-support corrosion, 5,[19][20][21][22] and that will be referred to as 'start-stop degradation' in the following. 23 The second AST which has not been investigated in the studies cited above simulates the variation in power output present during automotive application that results in potential fluctuations between ≈0.6 and ≈1.0 V RHE causing Pt dissolution (and re-deposition); 21,[24][25][26] it will be denoted 'load-cycle degradation '.…”

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confidence: 99%

Durability of Unsupported Pt-Ni Aerogels in PEFC Cathodes

Henning

Herranz

Ishikawa

et al. 2017

J. Electrochem. Soc.

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The commercial success of polymer electrolyte fuel cells (PEFCs) depends on the development of Pt-based oxygen reduction reaction (ORR) catalysts with greater activity and stability to reduce the amount of expensive noble metal per device. To advance toward this goal, we have tested a novel class of unsupported bimetallic alloy catalysts (aerogels) as the cathode material in PEFCs under two accelerated stress test conditions and compared it to a state-of-the-art carbon-supported benchmark (Pt/C). The investigated Pt 3 Ni aerogel shows little degradation under high potential conditions (> 1.0 V) which can occur during fuel starvation and start-up/shutdown of the cell. If tested under the same conditions, the Pt/C benchmark displays significant losses of electrochemical surface area and ORR activity due to carbon support corrosion as observed in cross section and transmission electron microscopy analysis. When testing the durability upon extended load cycling (0.6-1.0 V), Pt 3 Ni aerogel demonstrates less stability than Pt/C which is related to the severe Ni leaching from the alloy under such conditions. These findings highlight the advantages of using unsupported ORR catalysts in PEFCs and point to the reduction of non-noble metal dissolution as the next development step. Polymer electrolyte fuel cells (PEFCs) currently rely on large amounts of carbon-supported platinum (Pt/C) catalysts (≈0.4 mg Pt /cm 2 electrode ) to reduce the voltage losses due to the sluggish kinetics of the cathodic oxygen reduction reaction (ORR).1 Recent advancements in minimizing the Pt loading and associated costs were achieved by alloying platinum with other metals like Ni, Cu and Co which increases the Pt mass-specific ORR activity.2 On the other hand, these catalysts suffer from significant corrosion of the carbon support and Pt nanoparticles during PEFC operation which compromises their long-term efficiency and reliability.3 To specifically mitigate the issue of support stability, researchers have developed alternative corrosionresistant supports (e.g. conductive metal oxides 4-7 ), extended metal surfaces (e.g. 3 M nanostructured thin film catalysts 8 ) and unsupported materials (e.g. Pt-coated Ni, Co or Cu nanowires 9-11 ). Pursuing this last strategy, unsupported bimetallic Pt-Ni electrocatalysts with high specific surface area (≈30 m 2 /g Pt ) and nanochain network structure, referred to as aerogels, were synthesized in a previous work. 12These materials reach the U.S. Department of Energy target (DOE; i.e. 440 A/g Pt at 0.9 V vs. the reversible hydrogen electrode (V RHE )) for automotive PEFC application when tested as thin films by the rotating disk electrode (RDE) technique, 13 which is the standard tool employed by the majority of researchers in this field for initial assessment of catalyst activities. Considering that performance figures derived from such RDE experiments, often do not translate fully to the technical system, it is fundamental to also assess activity and durability in PEFCs to evaluate the real application p...

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“…13,14 At high hydrations the membrane swells with water, but at lower hydrations, drying causes contraction of the membrane and produces significant hygrothermal stresses. 13,15,16 During repeated humidity cycles these hygrothermal stresses can cause pinholes and cracks in the membrane, which contribute to the eventual failure of the membrane. A membrane must be elastic enough to accommodate for swelling and contraction due to humidity changes, and strong enough to withstand the associated hygrothermal stresses.…”

mentioning

confidence: 99%

Mechanical Performance of Polyiosoprene Copolymer Anion Exchange Membranes by Varying Crosslinking Methods

Vandiver

Caire

Ertem

et al. 2015

J. Electrochem. Soc.

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Anion exchange membranes (AEM) are polymer electrolytes that facilitate ion transport in alkaline fuel cells and electrochemical devices. Fabrication of mechanically durable AEMs with high ionic conductivity is a challenge. Here, a copolymer of isoprene and vinylbenzyl trimethylammonium and a terpolymer of isoprene, vinylbenzyl trimethylammonium and styrene were crosslinked by various methods, and properties, including conductivity and mechanical strength, were investigated at dry and saturated conditions. Polymer chemistry and degree of crosslinking significantly influenced conductivity, swelling, and mechanical properties. The terpolymer had a higher proportion of vinylbenzyl trimethylammonium units increasing the ion exchange capacity (IEC), but membranes could still be rendered insoluble by crosslinking. The higher IEC of the terpolymer resulted in higher chloride conductivity, 20-75 mS/cm at 50 • C and 95%RH, compared to 4-17 mS/cm for the copolymer at the same conditions. At dry conditions films were stiff, having Young's moduli between 100-740 MPa, but hydration caused severe softening, reducing moduli by 1-2 orders of magnitude. The severe softening effect of hydration was confirmed by dynamic mechanical analysis. The AEMs studied did not have adequate mechanical durability at hydrated conditions, additional work is needed to determine polymer chemistries and crosslinking methods that will produce robust AEMs for long-term use in fuel cells and electrochemical devices. Fuel cells are attractive energy conversion devices that utilize hydrogen to produce electrical energy for stationary and transportation applications, with the by-product being water.1,2 Electrolyzers utilize a similar principle to produce hydrogen from water using electrical energy. Fuel cells and electrolyzers both utilize a polymer electrolyte membrane to separate the catalyst layers and efficiently transport ions, while limiting crossover of other species.1,3 Proton exchange membranes (PEM), specifically perfluorosulfonic acid polymers such as Nafion, have been utilized almost exclusively for current fuel cells, owing to their high proton conductivity and suitable chemical and mechanical stability. 4,5 While PEM fuel cells have been widely researched and developed over the last few decades, anion exchange membrane (AEM) fuel cells offer potential advantages over PEMs. [6][7][8][9][10] The alkali nature of an AEM fuel cell allows redox reactions with nonplatinum catalysts and improves oxygen reduction kinetics. 6,9,10 On going research seeks to develop robust, well performing AEMs for use in fuel cells, electrolyzers, and other electrochemical devices.Anion exchange membranes must have a high ionic conductivity and be chemically and mechanically stable over the life-time of the fuel cell.6,9,10 Chemical stability is a concern in AEMs as hydroxide ions present in the membrane have the potential to degrade the polymer backbone and cation functionalities. 6,11,12 Hydroxide transport is inherently slower than proton transport, to compensate...

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A review of polymer electrolyte membrane fuel cell durability test protocols

Cited by 291 publications

References 78 publications

Effect of time-dependent material properties on the mechanical behavior of PFSA membranes subjected to humidity cycling

Effect of time-dependent material properties on the mechanical behavior of PFSA membranes subjected to humidity cycling

Durability of Unsupported Pt-Ni Aerogels in PEFC Cathodes

Mechanical Performance of Polyiosoprene Copolymer Anion Exchange Membranes by Varying Crosslinking Methods

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