Self-aggregating cationic-chains enable alkaline stable ion-conducting channels for anion-exchange membrane fuel cells

Zhang, Jianjun; Zhang, Kaiyu; Liang, Xian; Yu, Weisheng; Ge, Xiaolin; Shehzad, Muhammad A.; Ge, Zijuan; Yang, Zhengjin; Wu, Liang

doi:10.1039/d0ta11011f

Cited by 124 publications

(112 citation statements)

References 65 publications

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“…In 2018, Xu’s group designed a bi-imidazolium functionalized side-chain-type anion exchange membrane with a flexible hydrophilic spacer, which showed higher ionic conductivity and fuel-cell performance than an alkyl spacer-containing membrane at the same IEC. In their further research, piperidinium and ether-free backbone were used to replace the imidazolium and PPO backbone to achieve higher alkali resistance and ionic conductivity. Our previous work ,, also verified the contribution of alkoxy chain as a cross-linker or extender to the microphase separation morphology of the membrane.…”

Section: Introductionsupporting

confidence: 68%

Dual-Side-Chain-Grafted Poly(phenylene oxide) Anion Exchange Membranes for Fuel-Cell and Electrodialysis Applications

Wang

et al. 2021

ACS Sustainable Chem. Eng.

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Anion exchange membranes (AEMs) usually suffer from the "trade-off" between ion conduction and stability. In this work, a series of dual-side-chain-grafted poly(phenylene oxide) AEMs were synthesized to explore how the side-chain architectures influence membrane performance. Our investigations suggest that the AEM containing both a long hydrophobic extender (attached to the cation's central atom) and a hydrophilic additional side chain (beside the cation) show high hydroxide conductivity (21.3 mS/cm at 30 °C) and good chemical and dimensional stability (90.5% conductivity retention after 1 M NaOH treatment at 60 °C for 528 h). In addition, when a tri-cation side chain and a hydrophobic side chain are incorporated simultaneously, the resulting AEM shows further improved conductivity and stability (50.0 mS/cm at 30 °C; 90.6% conductivity retention after 1 M NaOH treatment at 60 °C for 528 h); it also shows excellent electrochemical performance when applied in a fuel cell and an electrodialyzer, accomplishing a peak power density of 506 mW/cm 2 and a current efficiency of 96.11%, respectively. Our side-chain manipulation strategy provides a new and effective pathway to balance the ionic conductivity and stability of AEMs.

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Section: Introductionsupporting

confidence: 68%

Dual-Side-Chain-Grafted Poly(phenylene oxide) Anion Exchange Membranes for Fuel-Cell and Electrodialysis Applications

Wang

et al. 2021

ACS Sustainable Chem. Eng.

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“…The high‐frequency intercept ( Z Re ) represents the ohmic resistance, which mainly includes the interface contact resistance and the membrane resistance. [ 54 , 55 ] Furthermore, the MEAs formed by various ionomer binders (PPO‐7Py4, PPO‐7Py7, and PPO‐7Py10) show comparable ohmic resistances of 0.032, 0.028, and 0.062 Ω cm 2 , respectively, in Figure 7f . The MEA based on PPO‐7Py7 exhibits the lowest non‐ohmic resistance which corresponds to the contact resistance between CL and membrane (the second intercept of the Nyquist plot); the phenomenon may be attributed to a well‐dispersed CL.…”

Section: Resultsmentioning

confidence: 99%

Interaction Regulation Between Ionomer Binder and Catalyst: Active Triple‐Phase Boundary and High Performance Catalyst Layer for Anion Exchange Membrane Fuel Cells

et al. 2021

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As one of the most crucial components, the catalyst layer (CL) plays a critical role in the performance of anion exchange membrane fuel cells (AEMFCs). However, the effect of the structural evolution of ionomer binder on the micromorphology and catalytic activity of CL is yet to be clarified. In this study, pyrrolidinum and quaternary ammonium cations are attached to the polyphenylene oxide (PPO) backbone through flexible spacer units (five, seven, or nine carbon atoms) with different terminal alkyl groups. The Van der Waals force and electrostatic repulsion between the ionomer binder and catalyst are regulated through the flexible spacer units and terminal alkyl groups to alleviate the agglomeration of catalyst particles and acquire a high catalytic activity. To evaluate the electrochemical stability of the cationic groups, the alkaline stability of the ionomer binder is tested under a constant voltage to simulate the true operational environment of the fuel cells. The results reveal that the degradation of the cation groups of ionomer binder is accelerated under a constant voltage condition. This phenomenon in neglect earlier, may serve as a useful reference for the synthesis and performance enhancement of ionomer binders.

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“…Generally, the AEMs are fabricated by amorphous polymers, with so many structural disorders hindering efficient ion transport, therefore showing low conductivity. Precise control over AEM structures to form the desired microphase separation morphology is believed to accelerate ion transport across the membrane through the continuous ionic channels. − Over the past decades, AEMs featuring the block, − clustered, , side-chain, − or graft/comb-shaped structure , have been successfully designed to construct the aforementioned ionic channels.…”

Section: Introductionmentioning

confidence: 99%

Flexible Bis-piperidinium Side Chains Construct Highly Conductive and Robust Anion-Exchange Membranes

Zhang

Liang

et al. 2021

ACS Appl. Energy Mater.

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Anion-exchange membranes (AEMs) with high ion conductivity and chemical stability are urgently needed for electrochemical energy storage and conversion technologies, e.g., anion-exchange membrane fuel cells (AEMFCs), redox flow batteries, and water electrolysis cells. Herein, a series of AEMs with aryl-ether-free polymer backbones bearing long flexible alkoxy-containing bis-piperidinium cationic side chains and additional hydrophobic alkyl chains were prepared. Multiple morphology analyses confirm that such a structure can promote the self-assembly of the cationic groups. The resulting interconnected ionic highways accelerate the ion transport of AEMs, which can reach up to 122 mS cm −1 at 80 °C. Moreover, the AEM shows excellent alkaline stability, with 93.4% ion conductivity remaining after aging in 2 M NaOH at 80 °C over 1000 h. The structural design opens an effective strategy for developing highly conductive and chemically robust AEMs.

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Self-aggregating cationic-chains enable alkaline stable ion-conducting channels for anion-exchange membrane fuel cells

Abstract: Precise manipulation over the polyelectrolyte self-assembly process, to form the desired microstructure with ion-conducting channels, is of fundamental and technological importance to many fields, such as fuel cells, flow batteries...

Cited by 124 publications

References 65 publications

Dual-Side-Chain-Grafted Poly(phenylene oxide) Anion Exchange Membranes for Fuel-Cell and Electrodialysis Applications

Dual-Side-Chain-Grafted Poly(phenylene oxide) Anion Exchange Membranes for Fuel-Cell and Electrodialysis Applications

Interaction Regulation Between Ionomer Binder and Catalyst: Active Triple‐Phase Boundary and High Performance Catalyst Layer for Anion Exchange Membrane Fuel Cells

Flexible Bis-piperidinium Side Chains Construct Highly Conductive and Robust Anion-Exchange Membranes

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