Alkaline‐Stable Anion‐Exchange Membranes with Barium [2.2.2]Cryptate Cations: The Importance of High Binding Constants

Zhang, Haixia; Wang, Xiaoyang; Wang, Yu; Zhang, Yin; Zhang, Wenjuan; You, Wei

doi:10.1002/ange.202217742

Cited by 4 publications

(2 citation statements)

References 66 publications

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“…1 ) and no observed deprotonation (see below). This approach differs from typical cryptate cationic groups where the metal center is easily displaced and inserted 44 ; the internal proton of in-DBD is endohedrally protected, not simply sterically protected. Collectively, these analyses support the uniqueness of the in-DBD structure, which originates from the enforced, single-well hydrogen bond and endohedral protection and the extraordinary mechanism of proton insertion.…”

Section: Resultsmentioning

confidence: 98%

An organic proton cage that is ultra-resistant to hydroxide-promoted degradation

Radford,

Saatkamp,

Bennet

et al. 2024

Nat Commun

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Alkaline polymer membrane electrochemical energy conversion devices offer the prospect of using non-platinum group catalysts. However, their cationic functionalities are currently not sufficiently stable for vapor-phase applications, such as fuel cells. Herein, we report 1,6-diazabicyclo[4.4.4]tetradecan-1,6-ium (in-DBD), a cationic proton cage, that is orders of magnitude more resistant to hydroxide-promoted degradation than state-of-the-art organic cations under ultra-dry conditions and elevated temperature, and the first organic cation-hydroxide to persist at critically low hydration levels ( < 10% RH at 80 °C). This high stability against hydroxide-promoted degradation is due to the unique combination of endohedral protection and intra-bridgehead hydrogen bonding that prevents the removal of the inter-cavity proton and lowers the susceptibility to Hofmann elimination. We anticipate this discovery will facilitate a step-change in the advancement of materials and electrochemical devices utilizing anion-exchange membranes based on in-DBD that will enable stable operation under extreme alkaline conditions.

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Section: Resultsmentioning

confidence: 98%

An organic proton cage that is ultra-resistant to hydroxide-promoted degradation

Radford,

Saatkamp,

Bennet

et al. 2024

Nat Commun

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show abstract

“…A polymer backbone, which alters the characteristics of the membrane, and ion-conducting head groups, which conduct OH − ions, comprise a polymer electrolyte appropriate for use as an AEM [ 20 , 21 ]. Both aryl ether-type and non-aryl ether-type polymers have been employed as polymer backbones, including poly(arylene ether ketone) (PEK) [ 22 , 23 , 24 ], poly(arylene ether sulfone) (PES) [ 25 , 26 ], poly(phenylene oxide) (PPO) [ 27 , 28 , 29 , 30 ], styrene ethylene butylene styrene (SEBS) [ 27 , 31 , 32 , 33 , 34 , 35 ], polyphenylene (PP) [ 12 , 32 , 33 , 36 , 37 ], and polyethylene (PE) [ 38 , 39 , 40 , 41 ].…”

Section: Introductionmentioning

confidence: 99%

Understanding the Effect of Triazole on Crosslinked PPO–SEBS-Based Anion Exchange Membranes for Water Electrolysis

Choi

Min

Mo³

et al. 2023

Polymers

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For anion exchange membrane water electrolysis (AEMWE), two types of anion exchange membranes (AEMs) containing crosslinked poly(phenylene oxide) (PPO) and poly(styrene ethylene butylene styrene) (SEBS) were prepared with and without triazole. The impact of triazole was carefully examined. In this work, the PPO was crosslinked with the non-aryl ether-type SEBS to take advantage of its enhanced chemical stability and phase separation under alkaline conditions. Compared to their triazole-free counterpart, the crosslinked membranes made with triazole had better hydroxide-ion conductivity because of the increased phase separation, which was confirmed by X-ray diffraction (XRD) and atomic force microscopy (AFM). Moreover, they displayed improved mechanical and alkaline stability. Under water electrolysis (WE) conditions, a triazole-containing crosslinked PPO–SEBS membrane electrode assembly (MEA) was created using IrO2 as the anode and a Pt/C catalyst as the cathode. This MEA displayed a current density of 0.7 A/cm2 at 1.8 V, which was higher than that of the MEA created with the triazole-free counterpart. Our study indicated that the crosslinked PPO–SEBS membrane containing triazoles had improved chemo-physical and electrical capabilities for WE because of the strong hydrogen bonding between triazole and water/OH−.

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Machine Learning‐Aided Design of Highly Conductive Anion Exchange Membranes for Fuel Cells and Water Electrolyzers

Zhang,

Yuan,

Zhang

et al. 2024

Advanced Materials

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Alkaline anion exchange membrane (AEM)‐based fuel cells (AEMFCs) and water electrolyzers (AEMWEs) are vital for enabling the efficient and large‐scale utilization of hydrogen energy. However, the performance of such energy devices is impeded by the relatively low conductivity of AEMs. The conventional trial‐and‐error approach to designing membrane structures has proven to be both inefficient and costly. To address this challenge, a fully connected neural network (FCNN) model is developed based on acid‐catalyzed AEMs to analyze the relationship between structure and conductivity among 180,000 AEM variations. Under machine learning guidance, anilinium cation‐type membranes are designed and synthesized. Molecular dynamics simulations and Mulliken charge population analysis validated that the presence of a large anilinium cation domain is a result of the inductive effect of N+ and benzene rings. The interconnected anilinium cation domains facilitated the formation of a continuous ion transport channel within the AEMs. Additionally, the incorporation of the benzyl electron‐withdrawing group heightened the inductive effect, leading to high conductivity AEM variant as screened by the machine learning model. Furthermore, based on the highly active and low‐cost monomers given by machine learning, the large‐scale synthesis of anilinium‐based AEMs confirms the potential for commercial applications.

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Alkaline‐Stable Anion‐Exchange Membranes with Barium [2.2.2]Cryptate Cations: The Importance of High Binding Constants

Cited by 4 publications

References 66 publications

An organic proton cage that is ultra-resistant to hydroxide-promoted degradation

An organic proton cage that is ultra-resistant to hydroxide-promoted degradation

Understanding the Effect of Triazole on Crosslinked PPO–SEBS-Based Anion Exchange Membranes for Water Electrolysis

Machine Learning‐Aided Design of Highly Conductive Anion Exchange Membranes for Fuel Cells and Water Electrolyzers

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