Backbone stability of quaternized polyaromatics for alkaline membrane fuel cells

Fujimoto, Cy; Kim, Dae-Sik; Hibbs, Michael; Wrobleski, Debra A.; Kim, Yu Seung

doi:10.1016/j.memsci.2012.08.045

Cited by 277 publications

(236 citation statements)

References 42 publications

Supporting

Mentioning

233

Contrasting

Order By: Relevance

“…Exposing the AEMS to humidity allows the polymer to uptake water, which has a plasticizing effect. 25,28,35 The water plasticizer generally reduces the elastic modulus, increases elongation, and decreases the stress to break. The change in mechanical properties due to humidity is dependent on the amount of water taken up by the polymer.…”

Section: Resultsmentioning

confidence: 99%

“…In this study, the extensional properties of three well-studied AEMs were investigated under different temperature and humidity conditions. The AEMs used in this study are the industrially produced polyetheretherketone (PEEK) reinforced Fumasep FAA-PEEK membrane from Fumatech, 26 an aminated tetramethyl polyphenylene (ATMPP) developed at Sandia National Laboratory, [27][28][29] and a radiation grafted poly(ethylene-cotetrafluoroethylene)-based quaternary ammonium AEM developed at the University of Surrey. 30,31 The three membranes were chosen as they have all been produced consistently in multi-gram quantities, the first under industrial quality control standards, the second in large research batches over multiple years, and the third from an industrially produced precursor film.…”

Section: H678mentioning

confidence: 99%

See 1 more Smart Citation

Mechanical Characterization of Anion Exchange Membranes by Extensional Rheology under Controlled Hydration

Vandiver

Caire

Carver

et al. 2014

J. Electrochem. Soc.

View full text Add to dashboard Cite

Alkali anion exchange membrane (AEM) based devices have the potential for electrochemical energy conversion using inexpensive catalysts and a variety of fuel types. Membrane stability and anion transport must be improved in AEMs before these devices can be fully realized. Mechanical failure of the membrane can contribute to failure of the device, thus membrane durability is critical to overall system design. Here, a study of the mechanical properties of three well-established AEMs uses a modified extensional rheometer platform to simulate tensile testing using small membrane samples. Mechanical properties were tested at 30 and 60 • C under dry or water saturated gas conditions. Water in the membrane has a plasticizing effect, softening the membrane and reducing strength. PEEK membrane reinforcement limits swelling producing negligible softening and only a 9% decrease in strength from dry to hydrated conditions at 30 • C. Higher cation concentration increases water uptake resulting in significant softening, a 57% reduction in Young's modulus, and a 67% reduction in strength when hydrated at 30 • C. In a working electrochemical device, AEMs must maintain integrity over a range of temperatures and hydrations, making it critical to considering mechanical properties when designing new membranes. Polymer electrolyte membrane fuel cells and electrolyzers are potentially disruptive technologies that will replace traditional heat engines such as internal combustion engines for transportation applications, portable electronics, and are scalable to larger energy storage facilities. Polymer electrolyte membrane fuel cells are suitable for transportation applications due to their low temperature start-up and operation, high power density, and quick refueling.1-3 Proton exchange membranes (PEMs) have dominated polymer electrolyte membrane fuel cell development in the last several decades, resulting in the development of relatively stable, well performing membranes.1-4 Current PEM fuel cells remain cost prohibitive due to high catalysts costs, as well as long-term durability issues. 3,5,6 Anion exchange membranes (AEMs) can also be utilized in polymer electrolyte membrane devices and have several potential benefits over PEMs. AEM fuel cells benefit from increased kinetics in an alkali media allowing more complex fuels then hydrogen and have the potential to utilize non-platinum catalysts to reduce costs. 7-11However, a number of challenges must be overcome before AEMs reach the performance and durability necessary for fuel cells and other electrochemical energy conversion devices. Hydroxide present in the AEM degrades many of the proposed cationic groups and some polymer backbones, making development of chemically stable AEMs difficult. 9,11,12 Additionally, transport of hydroxide in AEMs is inherently slower than protons in PEMs, 13 to compensate, the concentration of ionic groups is often increased in AEMs.8 Increasing ion concentration in AEMs increases water sorption in the polymer and can result in significant dimensional...

show abstract

Section: Resultsmentioning

confidence: 99%

Section: H678mentioning

confidence: 99%

Mechanical Characterization of Anion Exchange Membranes by Extensional Rheology under Controlled Hydration

Vandiver

Caire

Carver

et al. 2014

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…Figure 2 shows the reaction scheme for the synthesis of brominated PPO. The degree of functionalization (DF, number of bromine per polymer repeat unit) was 0.36 mol/mol (see 1 H NMR spectrum of brominated PPO in Figure S5). …”

Section: Synthesis Of Brominated Ppo (Brppo)-a Mixture Of Ppomentioning

confidence: 99%

“…Finally, by investigating the alkaline stability of AEMs synthesized by reaction of brominated PPO with 1,2-dimethylimidazole and modified imidazole bases (with 7 or 12 alkyl carbon chain at the N-3 position), we demonstrated that the increase in length of a long alkyl chain affixed to the N-3 position decreases the alkaline stability of the resultant imidazolium-based AEMs. There is a growing interest in using anion exchange membranes (AEMs) as separators in alkaline membrane fuel cells (AMFCs) 1,2 and in other energy conversion and storage systems such as redox flow batteries (RFBs), 3-5 alkaline water electrolyzers (AWEs) 6,7 and reverse electrodialysis (RED) cells. 8 The most commonly used AEMs reported in the literature contain quaternary ammonium groups, primarily in the form of benzyl trimethylammonium cations.…”

mentioning

confidence: 99%

“…There is a growing interest in using anion exchange membranes (AEMs) as separators in alkaline membrane fuel cells (AMFCs) 1,2 and in other energy conversion and storage systems such as redox flow batteries (RFBs), [3][4][5] alkaline water electrolyzers (AWEs) 6,7 and reverse electrodialysis (RED) cells. 8 The most commonly used AEMs reported in the literature contain quaternary ammonium groups, primarily in the form of benzyl trimethylammonium cations.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Alkaline Stability of Poly(Phenylene Oxide) Based Anion Exchange Membranes Containing Imidazolium Cations

Wang

Parrondo

Ramani

2016

J. Electrochem. Soc.

View full text Add to dashboard Cite

Two modified imidazole bases (1-heptyl-2-methyl-imidazole and 1-dodecyl-2-methyl-imidazole) were synthesized, each with a long alkyl chain (7 or 12 carbon) attached to the N-3 position. Anion exchange membranes (AEMs) were prepared with imidazolium cations derived from these bases that were either grafted directly onto the benzyl position of poly(phenylene oxide) (PPO) or affixed to the PPO using a hexyl spacer chain. First, we reacted 1-methylimidazole with brominated PPO and with PPO with a hexyl spacer chain. By comparing the alkaline stability of the resultant AEMs, we demonstrated that a hexyl spacer chain could improve AEM alkaline stability substantially. Second, by comparing the alkaline stability of PPO-based AEMs obtained by the reaction of brominated PPO with 1-methylimidazole and 1,2-dimethylimidazole, we showed that C-2-substituted (with a methyl group) imidazolium-based AEMs were much more stable in alkali than C-2-unsubstituted imidazolium-based AEMs. Finally, by investigating the alkaline stability of AEMs synthesized by reaction of brominated PPO with 1,2-dimethylimidazole and modified imidazole bases (with 7 or 12 alkyl carbon chain at the N-3 position), we demonstrated that the increase in length of a long alkyl chain affixed to the N-3 position decreases the alkaline stability of the resultant imidazolium-based AEMs. There is a growing interest in using anion exchange membranes (AEMs) as separators in alkaline membrane fuel cells (AMFCs) 1,2 and in other energy conversion and storage systems such as redox flow batteries (RFBs), 3-5 alkaline water electrolyzers (AWEs) 6,7 and reverse electrodialysis (RED) cells. 8 The most commonly used AEMs reported in the literature contain quaternary ammonium groups, primarily in the form of benzyl trimethylammonium cations.6,9-30 However, it had been shown that quaternary ammonium-based AEMs are sensitive toward Hofmann elimination 10,31 and direct nucleophilic elimination reactions 32,33 that result in loss of ion exchange capacity (IEC) and ionic conductivity. To resolve the stability problem inherent to quaternary-ammonium-group-containing AEMs, several alternative cations, including imidazolium, 31,34,35 benzimidazolium, 36 guanidinium, 37 phosphonium 38-40 and metal cations 41 have been proposed and investigated. Imidazolium-based AEMs have drawn researchers' interests mainly because of their high hydroxide-ion conductivities. 42 However, it has been reported that imidazoliumbased AEMs degrade under alkaline conditions at temperatures below 80• C. Ye and co-workers investigated the degradation mechanism of imidazolium-based AEMs at several relative humidities, temperatures and pH. They found that imidazolium-based AEMs were chemically stable at low temperatures, but relatively unstable at higher temperatures in alkaline conditions (degradation commences at 80• C when [KOH] >1 M). They postulated the following degradation mechanism: Ring-opening of the imidazolium ring was triggered by the nucleophilic attack of OH -on the imidazolium ring at the ...

show abstract

Anion Exchange Membranes

Shin

Bae

Kim

2017

The Chemistry of Membranes Used in Fuel Cells

View full text Add to dashboard Cite

Backbone stability of quaternized polyaromatics for alkaline membrane fuel cells

Cited by 277 publications

References 42 publications

Mechanical Characterization of Anion Exchange Membranes by Extensional Rheology under Controlled Hydration

Mechanical Characterization of Anion Exchange Membranes by Extensional Rheology under Controlled Hydration

Alkaline Stability of Poly(Phenylene Oxide) Based Anion Exchange Membranes Containing Imidazolium Cations

Anion Exchange Membranes

Contact Info

Product

Resources

About