Recent progress in anion exchange membranes (AEMs) in water electrolysis: synthesis, physio-chemical analysis, properties, and applications

Sriram, Ganesan; Dhanabalan, Karmegam; Ajeya, Kanalli V.; Aruchamy, Kanakaraj; Ching, Yern Chee; Oh, Tae Hwan; Jung, Ho-Young; Kurkuri, Mahaveer

doi:10.1039/d3ta04298g

Cited by 13 publications

(8 citation statements)

References 397 publications

(956 reference statements)

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“…The high conductivity of the AEMs is usually associated with an optimized nanomorphology of the membrane via the formation of well-developed percolating hydrophilic phase domains that are necessary for fast ion transport [ 26 ]. The flexibility and mobility of cationic chains significantly affect self-assembly and thus play an important role in the construction of ionic channels.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, SAXS and AFM measurements were performed to study any ionic clustering and phase separation of the AEMs. The characteristic separation length between ion-rich domains can be observed in terms of the values of q corresponding to the so-called ionomeric peak [ 26 ]. As shown in Figure 4 , although there is a flexible n -pentyl spacer between the cations and rigid backbone which could potentially induce hydrophilic/hydrophobic separation, no ionomer peak was observed for both samples, suggesting that no obvious phase separation occurred.…”

Section: Resultsmentioning

confidence: 99%

“…Super acid-catalyzed polyhydroxyalkylation was used as a simple route for preparing aryl-ether free polyaromatics that can be easily functionalized with stable cationic groups to afford high performance AEMs [ 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Zhang et al synthesized QA-tethered poly(isatin biphenylene) with an aryl-ether free backbone and the obtained AEMs exhibited high hydroxide conductivity and high alkaline stability in 2M NaOH at 80 °C for 1050 h [ 27 ].…”

Section: Introductionmentioning

confidence: 99%

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Cycloaliphatic Quaternary Ammonium Functionalized Poly(oxindole biphenyl) Based Anion-Exchange Membranes for Water Electrolysis: Stability and Performance

Gjoshi,

Loukopoulou,

Plevova

et al. 2023

Polymers

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Mechanically robust anion-exchange membranes (AEMs) with high conductivity and long-term alkali resistance are needed for water electrolysis application. In this work, aryl-ether free polyaromatics containing isatin moieties were prepared via super acid-catalyzed copolymerization, followed by functionalization with alkaline stable cyclic quaternary ammonium (QA) cationic groups, to afford high performance AEMs for application in water electrolysis. The incorporation of side functional cationic groups (pyrrolidinium and piperidinium) onto a polymer backbone via a flexible alkyl spacer aimed at conductivity and alkaline stability improvement. The effect of cation structure on the properties of prepared AEMs was thoroughly studied. Pyrrolidinium- and piperidinium-based AEMs showed similar electrolyte uptakes and no obvious phase separation, as revealed by SAXS and further supported by AFM and TEM data. In addition, these AEMs displayed high conductivity values (81. 5 and 120 mS cm−1 for pyrrolidinium- and piperidinium-based AEM, respectively, at 80 °C) and excellent alkaline stability after 1 month aging in 2M KOH at 80 °C. Especially, a pyrrolidinium-based AEM membrane preserved 87% of its initial conductivity value, while at the same time retaining its flexibility and mechanical robustness after storage in alkaline media (2M KOH) for 1 month at 80 °C. Based on 1H NMR data, the conductivity loss observed after the aging test is mainly related to the piperidinium degradation that took place, probably via ring-opening Hofmann elimination, alkyl spacer scission and nucleophilic substitution reactions as well. The synthesized AEMs were also tested in an alkaline water electrolysis cell. Piperidinium-based AEM showed superior performance compared to its pyrrolidinium analogue, owing to its higher conductivity as revealed by EIS data, further confirming the ex situ conductivity measurements.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cycloaliphatic Quaternary Ammonium Functionalized Poly(oxindole biphenyl) Based Anion-Exchange Membranes for Water Electrolysis: Stability and Performance

Gjoshi,

Loukopoulou,

Plevova

et al. 2023

Polymers

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“…The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/polym16111464/s1, Figure S1: 1…”

Section: Supplementary Materialsmentioning

confidence: 99%

“…Hydrogen energy, as an important environmentally friendly and clean energy source, is considered to possess high energy density and emit no carbon emissions, and has become a promising alternative to fossil fuels [ 1 , 2 , 3 , 4 ]. Unlike conventional methods reliant on fossil fuels with carbon emissions, green hydrogen is generated through processes that generate zero or minimal carbon emissions, such as water electrolysis technology [ 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

A Hydrophilic Polyethylene Glycol-Blended Anion Exchange Membrane to Facilitate the Migration of Hydroxide Ions

Gao,

Jin,

et al. 2024

Polymers

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As one of the most important sources for green hydrogen, anion exchange membrane water electrolyzers (AEMWEs) have been developing rapidly in recent decades. Among these components, anion exchange membranes (AEMs) with high ionic conductivity and good stability play an important role in the performance of AEMWEs. In this study, we have developed a simple blending method to fabricate the blended membrane ImPSF-PEGx via the introduction of a hydrophilic PEG into the PSF-based ionic polymer. Given their hydrophilicity and coordination properties, the introduced PEGs are beneficial in assembling the ionic groups to form the ion-conducting channels. Moreover, an asymmetric structure is observed in ImPSF-PEGx membranes with a layer of finger-like cracks at the upper surface because PEGs can act as pore-forming agents. During the study, the ImPSF-PEGx membranes exhibited higher water uptake and ionic conductivity with lower swelling ratios and much better mechanical properties in comparison to the pristine ImPSF membrane. The ImPSF-PEG1000 membrane showed the best overall performance among the membranes with higher ionic conductivity (82.6 mS cm−1 at 80 °C), which was approximately two times higher than the conductivity of ImPSF, and demonstrated better mechanical and alkaline stability. The alkaline water electrolyzer assembled by ImPSF-PEG1000 achieved a current density of 606 mA cm−2 at 80 °C under conditions of 1 M KOH and 2.06 V, and maintained an essentially unchanged performance after 48 h running.

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All‐Aromatic Polymer‐Based Anion Conductive Ionomers with Different Ion Exchange Capacities for Water Electrolysis

Nara,

Tomita,

Nagasawa

et al. 2024

Adv Eng Mater

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Anion exchange membrane water electrolysis (AEMWE) is vital for efficient, environmentally friendly, and cost‐effective hydrogen production. Herein, fluorene‐based polymers containing alkyl ammonium groups with different ion exchange capacities (IECs) for use in anion exchange membranes (AEMs) and anion exchange ionomers (AEIs) are investigated. Among the AEMs tested, the AEM with an IEC of 2.2 meq g−1 shows the highest anion conductivity because of its efficient water uptake characteristics. The anode catalyst layers utilize AEIs and iridium oxide catalyst particles. It is essential to select AEIs with appropriate IEC and suitable solvents for high‐performance anodes in water electrolyzers. Morphological and physical property evaluations reveal that moderate hydrophilicity and suppression of water swelling of AEIs improve water electrolysis performance. The optimized catalyst layer achieves better water electrolysis performance (2.64 V, 1.8 A cm−2 at 30 °C) than the conventional catalyst layer (3.83 V, 1.8 A cm−2 at 30 °C). Although the water electrolysis performance in this study falls short of the final targets, further research on anion conductive polymers and catalyst layers, based on this study's findings, is expected to promote practical applications of AEMWEs.

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Recent progress in anion exchange membranes (AEMs) in water electrolysis: synthesis, physio-chemical analysis, properties, and applications

Abstract: An overview of recent advancements in anion exchange membranes (AEMs) and their performance in water electrolysis is provided, and the progress of an electrocatalyst for anion exchange membrane water electrolysis (AEMWE) is also discussed.

Cited by 13 publications

References 397 publications

Cycloaliphatic Quaternary Ammonium Functionalized Poly(oxindole biphenyl) Based Anion-Exchange Membranes for Water Electrolysis: Stability and Performance

Cycloaliphatic Quaternary Ammonium Functionalized Poly(oxindole biphenyl) Based Anion-Exchange Membranes for Water Electrolysis: Stability and Performance

A Hydrophilic Polyethylene Glycol-Blended Anion Exchange Membrane to Facilitate the Migration of Hydroxide Ions

All‐Aromatic Polymer‐Based Anion Conductive Ionomers with Different Ion Exchange Capacities for Water Electrolysis

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