Anion conducting multiblock copolymer membranes with partial fluorination and long head-group tethers

Li, Lisha; Ahlfield, John M.; Tricker, Andrew W.; Chu, Deryn; Kohl, Paul A.

doi:10.1039/c6ta06653d

Cited by 70 publications

(48 citation statements)

References 35 publications

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“…We believe that the introduction of a hydrophobic block promotes systematic phase segregation, 17 which allows the hydrophilic block to create more efficient ion conduction and gas diffusion channels. From this it can be inferred that the electrolyte wetting of the 3-dimensional interfacial area in the gas diffusion electrode is increased, thereby reducing mass transfer resistances and improving the overall cell performance.…”

Section: Resultsmentioning

confidence: 99%

“…These materials have all been demonstrated to be stable at this time scale in alkaline conditions in a previous study. 17 Electrochemical impedance spectroscopy (EIS) data was collected for the top performing cells approximately every 24 h throughout the duration of each experiment. As in the fuel cell experiments above, the same membrane and hardware was used for all devices, therefore any detectable differences in the high-frequency intercept can be attributed to the varying interfacial quality between the electrodes and the membrane.…”

Section: Resultsmentioning

confidence: 99%

“…In this paper, a set of ionomers were synthesized per Liu et al 17 and were tested for their viability as anion conducting ionomers in * Electrochemical Society Student Member. * * Electrochemical Society Fellow.…”

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confidence: 99%

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Anion Conducting Ionomers for Fuel Cells and Electrolyzers

Ahlfield

Huang

et al. 2017

J. Electrochem. Soc.

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The design of new anion exchange ionomers for use in electrochemical devices is a critical step in improvement of anionic fuel cells and electrolyzers. Although these materials share some targeted goals with anion exchange membranes (AEMs), there are several different property requirements. Since ionomers are used within electrode layers, they do not serve as a primary separator for fuel and air. Rather, they act as a transport facilitator in the electrode where a high degree of mass transport is required. In this study, a series of anionic ionomers is synthesized and tested in hybrid fuel cells and AEM electrolyzers. These ionomers are based on a series of materials which include block copolymer AEMs with alkyl tethers that have been modified to be used as anion conductors. The newly synthesized ionomers were tested in both fuel cell and electrolysis devices. In situ testing of these materials shows that lower molecular weight materials outperform their higher molecular weight counterparts. Additionally, the use of a block copolymer with the introduction of a hydrophobic spacer further increased device performance.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Anion Conducting Ionomers for Fuel Cells and Electrolyzers

Ahlfield

Huang

et al. 2017

J. Electrochem. Soc.

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“…Anion conductive polymers are used to compliment cation conductive polymer in dialysis or they can be used by themselves giving specific advantages . High ionic conductivity and chemical stability are universal goals which can be improved through phase segregation from a block copolymer structure . Block copolymers form efficient ion channels which confines the mobile hydroxide ion to ion conductive phase leading to better chemical stability, compared to random copolymers.…”

Section: Introductionmentioning

confidence: 99%

“…However, BTMA cations are susceptible to other degradation processes in alkaline conditions including direct nucleophilic substitution of hydroxide ions, and elimination via ylide formation . Recent studies have shown that long, alkyl chain tethered trimethyl ammonium (TMA) have excellent stability in alkaline environments at elevated temperature . The long alkyl chain lowers the electron‐withdrawing inductive effect and the resonance effect of the benzene ring when a benzyl attachment is used .…”

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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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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Cation–dipole interaction that creates ordered ion channels in an anion exchange membrane for fastOH⁻conduction

Zhang

et al. 2021

AIChE Journal

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Precise control over polyelectrolyte architecture, engineered for self-assembly of ion-conducting channels, is of fundamental and technological importance to many fields, for example, fuel cells and redox flow batteries and electrodialysis. Building on recent advances with the supramolecular chemistry, we introduce inter/intramolecular cation-dipole interactions between pendent quaternary ammoniums cations and polar polyethylene glycol grafts in an anion-exchange membrane (AEM). Such interactions lead to desirable, ordered ion-conducting pathways when in the membrane form. Comparison of the results of molecular dynamics simulation with 1 H NMR and nano-scale microscopy analyses show that the cation-dipole interactions enhance self-assembly and the formation of interconnected ionic network domains, providing three-dimensional pathways for both water and ion transport. The resultant AEM exhibits high OH − conductivity (49 mS cm −1 at 30 C) and a completive peak power density of 622 mW cm −2 at 70 C when tested in a H 2 /O 2 single-cell alkaline membrane fuel cell.

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Anion conducting multiblock copolymer membranes with partial fluorination and long head-group tethers

Abstract: Multiblock copolymer with long head-group tethers were synthesized as anion exchange membranes with high ionic conductivity and good alkaline stability.

Cited by 70 publications

References 35 publications

Anion Conducting Ionomers for Fuel Cells and Electrolyzers

Anion Conducting Ionomers for Fuel Cells and Electrolyzers

Anion conducting multiblock copolymers with different tethered cations

Cation–dipole interaction that creates ordered ion channels in an anion exchange membrane for fastOH⁻conduction

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Anion conducting multiblock copolymer membranes with partial fluorination and long head-group tethers

Abstract: Multiblock copolymer with long head-group tethers were synthesized as anion exchange membranes with high ionic conductivity and good alkaline stability.

Cited by 70 publications

References 35 publications

Anion Conducting Ionomers for Fuel Cells and Electrolyzers

Anion Conducting Ionomers for Fuel Cells and Electrolyzers

Anion conducting multiblock copolymers with different tethered cations

Cation–dipole interaction that creates ordered ion channels in an anion exchange membrane for fastOH−conduction

Contact Info

Product

Resources

About

Cation–dipole interaction that creates ordered ion channels in an anion exchange membrane for fastOH⁻conduction