Poly(arylene ether) Ionomers with Pendant Quinuclidium Groups and Varying Molecular Weight for Alkaline Electrodes

Zhou, Junfeng; Joseph, K. Abraham; Ahlfield, John M.; Park, Doh-Yeon; Kohl, Paul A.

doi:10.1149/2.077306jes

Cited by 20 publications

(13 citation statements)

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“…The high electron density around the beta‐hydrogens and the steric shielding in the β‐positions lowers the risk of Hofmann elimination . In addition to trimethyl quaternary ammonium cations, other cation groups, such as quinuclidium, phosphonium, imidazolium, and guanidinium have also been reported to each have advantages. However, the test conditions and polymer structure in the different publications varies making it sometimes difficult to quantitatively compare the performance of the different head‐groups.…”

Section: Introductionmentioning

confidence: 99%

“…The conductivity of quinuclidium (1‐azaoniumbicyclo[2,2,2]octane), a quaternary ammonium cation formed by quaternization of a polycyclic amine 1‐azabicyclo[2,2,2]octane (ABCO), has been studied . Quinuclidium has a larger van der Waals volume than the TMA head group, which may facilitate the formation of larger ion conductive channels to enhance ion mobility in the membrane.…”

Section: Introductionmentioning

confidence: 99%

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Anion conducting multiblock copolymers with different tethered cations

Kohl

2018

J. Polym. Sci. Part A: Polym. Chem.

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A multiblock copoly(arylene ether) polymer was used to quantitatively compare the ion conducting channels formed by three different, tethered cation head‐groups. The synthesis allowed for the formation of an exact number of tethers on each repeat unit. Three head‐groups, quaternary trimethylammonium (TMA), quinuclidium (ABCO), and tris(2,4,6‐trimethoxyphenyl)phosphonium (TTMPP) cation head‐groups were compared in terms of size of the conducting channels, ionic conductivity of the mobile hydroxide ion, mechanical properties, quantity of productive and unproductive water, and chemical stability of the membrane in base. The interdomain spacing showed that multiblock copolymers with larger cations formed larger ion conduction channels in the membrane. Larger cations resulted lower ion exchange capacity (IEC) even though the polymer backbone and tether arrangements were identical. TMA was the most stable cation after exposure to 1 M NaOH at 60 °C for 20 days. ABCO had a lower number of bound water molecules and a 22% loss in ion conductivity after treatment in 1 M NaOH at 60 °C for 20 days due to the higher hydroxide ion concentration in the ion conductive blocks. Membranes with TMA head‐groups also had the best mechanical properties. Two membrane preparation methods were compared. The presence of the cation head‐groups assists in phase segregation. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1395–1403

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anion conducting multiblock copolymers with different tethered cations

Kohl

2018

J. Polym. Sci. Part A: Polym. Chem.

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“…Polyelectrolyte membranes, namely, anion exchange membranes (AEMs) and proton exchange membranes (PEMs) are a critical component of fuel cells. The benefits of using AEMs in AEMFCs over PEMs in PEMFCs include the use of non‐precious catalysts, facile reaction kinetics, and reduced fuel crossover [9–15] …”

Section: Introductionmentioning

confidence: 99%

“…The benefits of using AEMs in AEMFCs over PEMs in PEMFCs include the use of non-precious catalysts, facile reaction kinetics, and reduced fuel crossover. [9][10][11][12][13][14][15] Hydrogen is considered as an alternative energy carrier to generate power for domestic, industrial, and transportation sectors. [16][17][18] This renewable and sustainable energy system is important because of its high energy density and reversible conversion between hydrogen and electricity.…”

Section: Introductionmentioning

confidence: 99%

Recent Advancement on Anion Exchange Membranes for Fuel Cell and Water Electrolysis

Mandal

2020

ChemElectroChem

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Highly conductive anion exchange membranes (AEMs) are one of the few requirements to produce high power during fuel cell operation and for efficient hydrogen production through water electrolysis. The use of chemically stable and cheap AEMs with platinum group metal (PGM)‐free catalysts is suitable for reducing the overall cost of hydrogen production and fuel cell operation. The in situ durability of anion exchange membrane fuel cells (AEMFCs) and anion exchange membrane water electrolyzers (AEMWEs) for several hundred hours is necessary for the widespread application of fuel cell and water electrolysis technologies. This Minireview highlights the best results reported recently in alkaline membrane fuel cells and water electrolysis. The achievable AEMFCs performances are noteworthy using Pt‐free anode and cathode electrocatalysts. Remarkable durability in AEMFCs is witnessed, although the durability is a concern for AEMWEs. Moreover, the current challenges and future directions of AEMFCs and AEMWEs are briefly summarized.

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“…It allows for the study and evaluation of AEM ionomers separately from anion exchange membranes, which has resulted in a few materials being developed explicitly as ionomers rather than membranes. 5 Because ionomers and membranes serve different functions in the cell, it is reasonable to assume that the materials used for these functions should be different. However, in order to study AEM ionomers previously, they were required to be used in conjunction with an anion exchange membrane, which makes deconvolution of ionomer from membrane performance difficult.…”

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PEM/AEM Junction Design for Bipolar Membrane Fuel Cells

Ahlfield

Kohl

2017

J. Electrochem. Soc.

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The combination of proton exchange membrane (PEM) and anion exchange membrane (AEM) materials to form a bipolar membrane (BPM) is of interest in hybrid electrochemical devices to mitigate the disadvantages of their monopolar counterparts. The PEM-AEM interface is a critical component in bipolar membrane fuel cell operation. In this study, mono-and di-membrane bipolar membranes were fabricated. Interfacial materials with varying conductivities were used in order to control the location of the junction within the di-membrane BPMs. Mono-membrane BPMs were constructed via conversion of a single face of a monopolar membrane (Nafion). The membranes were used in fully functional fuel cells and characterized via electrochemical impedance spectroscopy (EIS). For the di-membrane BPMs, use of a conductive interface consisting of a single ion conductive material resulted in devices with lower interfacial resistance as compared to a neutral interface. When comparing conductive interface materials, anion-conductive materials provided lower total membrane resistance than proton-conductive materials. This decrease is due to positioning the junction closer to the anode and farther from the air-cathode. These results show that the formation of the optimal junction is critically dependent on fabrication technique and location. Polymeric membrane-based fuel cells are a promising candidate to provide clean, efficient, and energy dense power sources. Of the primary types of these fuel cells, proton exchange membrane (PEM) fuel cells have capabilities of producing extremely high power densities, and the materials used as the proton exchange membrane (e.g. Nafion) are thermally and mechanically robust, allowing for long-term operation. Despite these features, there are several drawbacks relating to the operation of these devices under acidic conditions. First, the migration of protons from anode to cathode results in electro-osmotic drag of water (and methanol, where applicable) which can lead to a phenomenon known as "cathode flooding" or a blockage of transport passageways with water. Second, both the catalytic and polymeric materials required to survive the harsh acidic operating environment are expensive to manufacture. Third, both the metal catalyst and its carbon support are subject to corrosion at low pH.One alternative to the PEM fuel cell is the anion exchange membrane (AEM) fuel cell. This configuration addresses many of the shortcomings of the PEM cell simply by operating under alkaline (high pH) conditions. AEM fuel cells potentially address many of the issues inherent with PEM devices. The basic operating environment is much more conducive to the oxygen reduction reaction (ORR), which opens the possibility of using non-platinum based (cheaper) catalysts.1-3 Additionally, anion exchange membranes are typically hydrocarbon based, and as such are less expensive to manufacture than Nafion and other perfluorosulfonic acid (PFSA) membranes used in PEM devices. Another benefit is the reversed direction of ion transport through th...

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Poly(arylene ether) Ionomers with Pendant Quinuclidium Groups and Varying Molecular Weight for Alkaline Electrodes

Cited by 20 publications

References 22 publications

Anion conducting multiblock copolymers with different tethered cations

Anion conducting multiblock copolymers with different tethered cations

Recent Advancement on Anion Exchange Membranes for Fuel Cell and Water Electrolysis

PEM/AEM Junction Design for Bipolar Membrane Fuel Cells

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