Fuel cell evaluation of anion exchange membranes based on poly(phenylene oxide) with different cationic group placement

Carlson, Annika; Eriksson, Björn; Olsson, Joel; Lindbergh, Göran; Jannasch, Patric; Lindström, Rakel Wreland

doi:10.1039/c9se01143a

Cited by 17 publications

(10 citation statements)

References 41 publications

(85 reference statements)

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“…The ionomer–catalyst interactions and gas permeability can be tuned by the structure and conformation of both the aromatic ionomer backbone and the tethered cations. − Figure C shows a significant enhancement of fuel cell performance by slightly altering the ionomer structure . The symmetric methyl groups on the phenyl backbone increase the fractional free volume in the ionomer so that the hydrogen permeability increased.…”

Section: Alkaline Membrane/ionomer Design and Synthesismentioning

confidence: 99%

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

et al. 2022

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Hydrogen energy-based electrochemical energy conversion technologies offer the promise of enabling a transition of the global energy landscape from fossil fuels to renewable energy. Here, we present a comprehensive review of the fundamentals of electrocatalysis in alkaline media and applications in alkaline-based energy technologies, particularly alkaline fuel cells and water electrolyzers. Anion exchange (alkaline) membrane fuel cells (AEMFCs) enable the use of nonprecious electrocatalysts for the sluggish oxygen reduction reaction (ORR), relative to proton exchange membrane fuel cells (PEMFCs), which require Pt-based electrocatalysts. However, the hydrogen oxidation reaction (HOR) kinetics is significantly slower in alkaline media than in acidic media. Understanding these phenomena requires applying theoretical and experimental methods to unravel molecularlevel thermodynamics and kinetics of hydrogen and oxygen electrocatalysis and, particularly, the proton-coupled electron transfer (PCET) process that takes place in a proton-deficient alkaline media. Extensive electrochemical and spectroscopic studies, on single-crystal Pt and metal oxides, have contributed to the development of activity descriptors, as well as the identification of the nature of active sites, and the rate-determining steps of the HOR and ORR. Among these, the structure and reactivity of interfacial water serve as key potential and pH-dependent kinetic factors that are helping elucidate the origins of the HOR and ORR activity differences in acids and bases. Additionally, deliberately modulating and controlling catalyst−support interactions have provided valuable insights for enhancing catalyst accessibility and durability during operation. The design and synthesis of highly conductive and durable alkaline membranes/ionomers have enabled AEMFCs to reach initial performance metrics equal to or higher than those of PEMFCs. We emphasize the importance of using membrane electrode assemblies (MEAs) to integrate the often separately pursued/optimized electrocatalyst/support and membranes/ionomer components. Operando/in situ methods, at multiscales, and ab initio simulations provide a mechanistic understanding of electron, ion, and mass transport at catalyst/ionomer/membrane interfaces and the necessary guidance to achieve fuel cell operation in air over thousands of hours. We hope that this Review will serve as a roadmap for advancing the scientific understanding of the fundamental factors governing electrochemical energy conversion in alkaline media with the ultimate goal of achieving ultralow Pt or precious-metal-free highperformance and durable alkaline fuel cells and related technologies.

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Section: Alkaline Membrane/ionomer Design and Synthesismentioning

confidence: 99%

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

et al. 2022

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“…Beyond the performance of poly(benzimidazolium)s, poly(arylimidazolium)s provide an avenue to increase the stability of AEM-based fuel cells because of their inherently superior alkaline stability. ,,− These polycations are ionenes in which imidazolium is a component of the primary chain. Architecturally comparable ionenes include those based on arylene piperidinium and N -spirocyclic quaternary ammonium primary chains, in contrast to polyelectrolytes having pendant cations. ,− …”

Section: Introductionmentioning

confidence: 99%

Tuning Ion Exchange Capacity in Hydroxide-Stable Poly(arylimidazolium) Ionenes: Increasing the Ionic Content Decreases the Dependence of Conductivity and Hydration on Temperature and Humidity

Overton

Cao

et al. 2020

Macromolecules

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Increasing the ion exchange capacity (IEC, mmol• g −1 ) of anion exchange membranes (AEMs) decreases the dependence of ionic conductivity (σ) and ion pair hydration on limiting conditions of temperature and humidity. We present novel, hydroxide-stable polycationic ionenes having penta-substituted imidazolium repeating units. Variation of N,N′-dialkyl substituents having 1−4 carbons yields a range in IEC (Cl) (1.56− 2.32 mmol•g −1 ). The trend of σ (Cl) ∼ IEC is in agreement with comparable poly(arylimidazolium)s. This is the first report crosscorrelating water uptake (WU) and ionic conductivity of a homologous series of poly(arylimidazolium) ionenes. The AEMs of higher IEC have a lower range in σ and hydration number (λ = WU / IEC) within limits of temperature and humidity. Decreasing IEC correlates to increasing effective activation energy of ion transport (E a(eff.) ), at constant hydration. The AEM of N,N′-dimethyl-2,4,5-arylimidazolium repeating units and the highest IEC provides σ (Cl) = 12 mS•cm −1 (80 °C, 95 RH%) and σ (OH) = 120 mS•cm −1 (40 °C, 90 RH%).

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“…Thus, the PPO-SDSU membrane with an IEC of 1.91 meq g −1 exhibited a hydroxide conductivity of 31.9 mS cm −1 and a linear dimensional swelling of 9.6% at 20 °C. Carlson et al [ 151 ] synthesized the AEMs of poly (phenylene oxide)-membranes with a five-carbon alkyl spacer between the backbone and a trimethylalkylammonium (TMA) or piperidinium (Pip) cationic group. The AEMs demonstrated IECs between 1.5 and 1.9 mequiv g −1 for TMA and Pip, respectively.…”

Section: Overview Of Fuel Cellsmentioning

confidence: 99%

Anion Exchange Membranes for Fuel Cell Application: A Review

et al. 2022

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The fuel cell industry is the most promising industry in terms of the advancement of clean and safe technologies for sustainable energy generation. The polymer electrolyte membrane fuel cell is divided into two parts: anion exchange membrane fuel cells (AEMFCs) and proton exchange membrane fuel cells (PEMFCs). In the case of PEMFCs, high-power density was secured and research and development for commercialization have made significant progress. However, there are technical limitations and high-cost issues for the use of precious metal catalysts including Pt, the durability of catalysts, bipolar plates, and membranes, and the use of hydrogen to ensure system stability. On the contrary, AEMFCs have been used as low-platinum or non-platinum catalysts and have a low activation energy of oxygen reduction reaction, so many studies have been conducted to find alternatives to overcome the problems of PEMFCs in the last decade. At the core of ensuring the power density of AEMFCs is the anion exchange membrane (AEM) which is less durable and less conductive than the cation exchange membrane. AEMFCs are a promising technology that can solve the high-cost problem of PEMFCs that have reached technological saturation and overcome technical limitations. This review focuses on the various aspects of AEMs for AEMF application.

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Fuel cell evaluation of anion exchange membranes based on poly(phenylene oxide) with different cationic group placement

Abstract: Comparison of four poly(phenylene oxide) membranes in an AEMFC and the correlation between performance, ionic conductivity and water flux properties.

Cited by 17 publications

References 41 publications

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

Tuning Ion Exchange Capacity in Hydroxide-Stable Poly(arylimidazolium) Ionenes: Increasing the Ionic Content Decreases the Dependence of Conductivity and Hydration on Temperature and Humidity

Anion Exchange Membranes for Fuel Cell Application: A Review

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