A benzyltetramethylimidazolium-based membrane with exceptional alkaline stability in fuel cells: role of its structure in alkaline stability

Zhu, Yuan; He, Yubin; Ge, Xiaolin; Liang, Xian; Shehzad, Muhammad A.; Hu, Min; Liu, Yazhi; Wu, Liang; Xu, Tongwen

doi:10.1039/c7ta09095a

Cited by 103 publications

(69 citation statements)

References 44 publications

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“…Recent studies have shown that cyclic ammonium (24)(25)(26)(27) and tetraalkyl ammonium cations, specifically those with long alkyl chains (18)(19)(20)(28)(29)(30), have better alkaline stability than traditional benzyltrimethyl ammonium cations (31)(32)(33). Other cations, such as imidazolium (16,21,(34)(35)(36)(37)(38)(39)(40)(41)(42)(43), phosphonium (44)(45)(46)(47)(48)(49), and metal cations (50)(51)(52)(53)(54), have also been widely applied in various AAEMs. More specifically, pentasubstituted imidazolium (34)(35)(36)(37)(38), tetrakis(dialkylamino)phosphonium (44)(45)(46), and cobaltocenium (50,51) have shown superior alkaline stability.…”

Section: Significancementioning

confidence: 99%

Highly conductive and chemically stable alkaline anion exchange membranes via ROMP of trans -cyclooctene derivatives

You

Padgett

MacMillan

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

129

107

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Alkaline anion exchange membranes (AAEMs) are an important component of alkaline exchange membrane fuel cells (AEMFCs), which facilitate the efficient conversion of fuels to electricity using nonplatinum electrode catalysts. However, low hydroxide conductivity and poor long-term alkaline stability of AAEMs are the major limitations for the widespread application of AEMFCs. In this paper, we report the synthesis of highly conductive and chemically stable AAEMs from the living polymerization of trans-cyclooctenes. A trans-cyclooctene-fused imidazolium monomer was designed and synthesized on gram scale. Using these highly ring-strained monomers, we produced a range of block and random copolymers. Surprisingly, AAEMs made from the random copolymer exhibited much higher conductivities than their block copolymer analogs. Investigation by transmission electron microscopy showed that the block copolymers had a disordered microphase segregation which likely impeded ion conduction. A cross-linked random copolymer demonstrated a high level of hydroxide conductivity (134 mS/cm at 80°C). More importantly, the membranes exhibited excellent chemical stability due to the incorporation of highly alkaline-stable multisubstituted imidazolium cations. No chemical degradation was detected by 1 H NMR spectroscopy when the polymers were treated with 2 M KOH in CD 3 OH at 80°C for 30 d.alkaline anion exchange membrane | trans-cyclooctene | block and random copolymer | cross-linked polymer | transmission electron microscopy A lkaline anion exchange membranes (AAEMs) are a class of polymer electrolytes constructed from immobilized cations with hydroxide counteranions (1-3). AAEMs have been widely used for a variety of electrochemical applications, such as redox flow batteries, electrodialysis, and water electrolysis (4-7). One of the most important applications for AAEMs is their use as polyelectrolytes in alkaline exchange membrane fuel cells (AEMFCs). These devices can efficiently convert chemical energy in fuels (e.g., H 2 , hydrazine, and direct alcohols) into electricity. In comparison with proton exchange membrane fuel cells and aqueous alkaline fuel cells, AEMFCs are advantageous because they allow for rapid reduction of oxygen at the cathode, limit fuel cross-over, prevent the formation of carbonate precipitates, and are compatible with nonnoble electrocatalysts (8-12). Because of their essential role in AEMFCs, AAEMs have been extensively studied to optimize their performance and, in particular, to improve their hydroxide conductivity and alkaline stability.Hydroxide conductivity is one of the most important parameters used to evaluate AAEMs, because it is directly related to the ohmic resistance and power density of an AEMFC (9). There are several strategies to enhance the hydroxide conductivity of AAEMs. The most straightforward method is to increase the ion exchange capacity (IEC), such that more ions are present in AAEMs. However, a higher IEC typically results in higher water uptake. While the presence of water facilitates h...

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Section: Significancementioning

confidence: 99%

Highly conductive and chemically stable alkaline anion exchange membranes via ROMP of trans -cyclooctene derivatives

You

Padgett

MacMillan

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

129

107

View full text Add to dashboard Cite

show abstract

“…6(b) and Table S2). 13,23,35,[38][39][40][41][42][43][44] Moreover, at a constant discharge voltage of 0.6 V, the power density of BImPPO-2.1 drops from 202 mW cm -2 to 74 mW cm -2 (37 % of the initial value) in 3.4 h (Fig. 6c).…”

Section: Benefits Of Rotatable Ethylene Oxide Spacer For Fuel Cell Pementioning

confidence: 99%

Beneficial use of rotatable-spacer side-chains in alkaline anion exchange membranes for fuel cells

Zhu

Ding

Liang

et al. 2018

Energy Environ. Sci.

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214

111

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“…AEM of BQA-FPAE can be obtained by casting onto a glass plate and dried at 80°C for 4 h. . Water uptake, swelling, ion exchange capacity [40], conductivity [33] and fuel cell performance [41] were measured according to our previous literatures.…”

Section: Synthesis Of Gemini Cation Functionalized Fpae (Bqa-fpae)mentioning

confidence: 99%

Towards the gemini cation anion exchange membranes by nucleophilic substitution reaction

Zhang

Liang

et al. 2019

Sci. China Mater.

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As a critical component of alkaline fuel cells, anion exchange membranes determine the energy efficiency, output power density and the long term stability. Recently, the anion exchange membranes with gemini-cation side chains exhibit superior ion conductivity due to their good nanophase separation. However, the costly and complicated synthesis limits their scaling up and commercialization. To address this problem, a convenient synthetic procedure under mild conditions is well developed. A tertiary amine precursor is introduced onto the polymer by the nucleophilic substitution reaction to avoid the conventional chloro/bromo-methylation. Followed by a simple Menshutkin reaction with 6bromo-N,N,N-trimethylhexan-1-aminium bromide, the polymer electrolytes are obtained in a high yield. The resulting anion exchange membranes with high conductivity, good fuel cell performance and restricted swelling suggest the potential for the application in fuel cell devices.

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A benzyltetramethylimidazolium-based membrane with exceptional alkaline stability in fuel cells: role of its structure in alkaline stability

Abstract: Highly alkaline stable imidazolium-type membrane has been developed for fuel cells by protection of the imidazolium ring at C2, C4 and C5 positions.

Cited by 103 publications

References 44 publications

Highly conductive and chemically stable alkaline anion exchange membranes via ROMP of trans -cyclooctene derivatives

Highly conductive and chemically stable alkaline anion exchange membranes via ROMP of trans -cyclooctene derivatives

Beneficial use of rotatable-spacer side-chains in alkaline anion exchange membranes for fuel cells

Towards the gemini cation anion exchange membranes by nucleophilic substitution reaction

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