Hydroxide Transport in Anion-Exchange Membranes for Alkaline Fuel Cells

Ramírez, Sergio Castañeda; Paz, Rafael Esteban Ribadeneira

doi:10.5772/intechopen.77148

Cited by 8 publications

(5 citation statements)

References 50 publications

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“…The high relative permittivity of water (ε r = 80.2 at 20 °C, ε r = 55.5 at 100 °C), the effect of ion solvation on the mechanism of anion transport, − and the wider impact of hydration ,, on durability and performance of AEM-based devices inspire examination of the water uptake of this series of AEMs. The water uptake (WU, eq ) of DMP-PMPI-RR(Cl) under controlled humidity is calculated from the membrane mass measured by DVS.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

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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Section: ■ Results and Discussionmentioning

confidence: 99%

“…Water content plays an important role, and in particular the nanophase segregation between hydrophobic and hydrophilic regions. Even though Grotthuss mechanism enables a faster transport of hydroxide species through narrow bottlenecks in water channels, , both theoretical and experimental studies proved that the overall conductivity increases with growing λ and in the presence of well-defined water channels. ,,,, The increase in amination degree and IEC is generally expected to improve the ionic conductivity. ,, For PA membranes, however, a growth in IEC is associated with a reduced chain mobility due to the introduction of N-substituted pyrrole units, which in turn reduces the ionic conductivity above certain values of IEC and at relatively low λ. The experimental findings by Zhou et al , are in accordance with our simulations.…”

Section: Resultsmentioning

confidence: 99%

Computational Modeling of Hydrated Polyamine-Based Anion Exchange Membranes via Molecular Dynamics Simulation

Tomasino,

Mukherjee,

Neelalochana

et al. 2023

J. Phys. Chem. C

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The present study aims to investigate static and dynamic properties of polyamine-based anion exchange membranes (AEMs) using all-atom molecular dynamics simulations. The effects of the hydration level, degree of amination, and temperature on the properties of AEMs were systematically explored. The phase segregation and the formation of interconnected hydrophilic channels were visualized for different simulated membranes. Additionally, the variation of the diffusion coefficients of both water molecules and hydroxide anions as a function of the aforementioned parameters were computed, and the mechanical properties of the different membranes were studied. The results revealed that increasing the degree of amination and water uptake facilitates the transport of water and anionic species. However, this comes at the expense of the mechanical stability of the membrane due to water-induced plasticization, potentially leading to its irreversible deformation under operating conditions. We then demonstrate that a promising compromise solution between high conductivity and mechanical stability can be achieved by limiting the degree of amination to about 30%. These results furnish valuable insights into the development of improved AEMs.

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“…This transfers the defects to the neighboring molecule. At the end of the transfer, molecule rearranges to form a square planar configuration [66].…”

Section: Ion Transport Mechanismmentioning

confidence: 99%

Expanding the versatility and functionality of iontronic devices

Cherian

2021

Linköping Studies in Science and Technology. Dissertations

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Biological systems rarely use electrons as signal regulators, most of the transport and communication in these system utilize ions. The discovery of conjugated polymers and polyelectrolytes and their unique properties of mixed ionic electronic properties opened the possibility of using these in the domain of bioelectronics, which paved the way for the field of organic bioelectronics. After the introduction of the organic electronic ion pump (OEIP) in 2007, which utilizes both the ionic properties of conjugated polymers and polyelectrolytes, the new field of "iontronics" evolved. The OEIP is an organic polymer-based delivery system based on electrophoretic transport of biologically relevant and ionically charged species, without fluid flow and with high spatial, temporal, and dosage precision. These devices have been extensively studied for the past 14 years and have found numerous demonstrations in in vivo and in vitro delivery of bio-relevant ions for therapeutic application. This has, in parallel, resulted in the development of custom materials for ion exchange membranes (IEMs) within the OEIP.

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Hydroxide Transport in Anion-Exchange Membranes for Alkaline Fuel Cells

Cited by 8 publications

References 50 publications

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

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

Computational Modeling of Hydrated Polyamine-Based Anion Exchange Membranes via Molecular Dynamics Simulation

Expanding the versatility and functionality of iontronic devices

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