Polybenzimidazolium hydroxides – Structure, stability and degradation

Henkensmeier, Dirk; Cho, Hyeong Rae; Kim, Hyoung Juhn; Kirchner, Carolina Nunes; Leppin, Janine; Dyck, Alexander; Jang, Jong Hyun; Cho, Eunae; Nam, Suk Woo; Lim, Tae Hoon

doi:10.1016/j.polymdegradstab.2011.12.024

Cited by 105 publications

(73 citation statements)

References 27 publications

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“…Nevertheless, PBI can also be doped with KOH, achieving good performances when operating with hydrogen [19] or with alcohols [13,[20][21][22][23][24][25][26][27][28] as fuel. Furthermore, more recent studies have proposed the modification of the base polymer in order to improve its properties: (a) by providing anionic exchange groups by alkylating the polymer backbone [29][30][31], (b) by combining it with ionic liquids [32] and carbon nanotubes [27], and (c) using a thermal curing process [33], among the most important alternatives. Despite the very significant advances achieved, the classical PBI doped with KOH remains the primary candidate, especially for application in alcohol fuel cells.…”

Section: Introductionmentioning

confidence: 99%

KOH-doped polybenzimidazole for alkaline direct glycerol fuel cells

Couto

Linares

2015

Journal of Membrane Science

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Section: Introductionmentioning

confidence: 99%

KOH-doped polybenzimidazole for alkaline direct glycerol fuel cells

Couto

Linares

2015

Journal of Membrane Science

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“…In a typical anionexchange ionomer, both the polymer backbone and functional groups are subject to hydroxide attack, e.g., via β-Hoffman elimination or direct nucleophilic displacement of the functional groups. 7,8 Cleavage of the polymer backbone primarily affects the mechanical properties of the membrane, while loss of functionality disproportionately reduces hydroxide transport. However, recent work has shed light on the physico-chemistry of anion-conducting membrane materials.…”

mentioning

confidence: 99%

The Control and Effect of Pore Size Distribution in AEMFC Catalyst Layers

Britton

Holdcroft

2016

J. Electrochem. Soc.

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Catalyst ink for anion-exchange catalyst coated membranes based on FuMA-Tech FAA-3 membranes and ionomer typically requires high-boiling solvents. Here, we investigate the disproportionate effect of even small quantities of high-boiling solvent in the catalyst ink on the catalyst layer microstructure. High porosity in the mesoporous regime, 20-100 nm, is found to be an essential characteristic of effective anion-exchange catalyst layers for increasing membrane hydroxide ion conductivity and reducing mass-transport losses. High porosity in the nanoporous regime (<20 nm pore diameter) facilitates improvements in the kinetic region of polarization curves at the expense of mass-transport losses. New strategies are introduced to improve the control of distribution of pore sizes in the catalyst layer and to increase the mesoporosity. Beginning-of-life power densities for O 2 /H 2 anion exchange membrane fuel cells (AEMFCs), under zero backpressure, were accordingly increased from 276 to 428 mW · cm −2 , placing it among the highest AEMFC power densities reported in the literature under the conditions studied, representing a significant improvement over previously reported performances for FAA-3. The study highlights a need to develop anion-exchange solid polymer ionomers soluble in low-boiling solvents for preparing catalyst inks, and a more rigorous evaluation of porosimetry data and catalyst layer preparation methods for O 2 /H 2 polymer electrolyte fuel cells rely on the electrochemical oxygen reduction reaction (ORR) and the hydrogen oxidation reaction (HOR) (Fig. S1). In proton-exchange membrane fuel cells (PEMFC), the reactions occur a highly acidic environment and are facile on Pt electrocatalayst.1 An alkaline environment opens the possibility of using stable, high activity, non-noble catalysts, 1-3 but analogous hydroxide-exchange membrane fuel cells (AEMFC) are less welldeveloped and the hydroxide ion diffuses more slowly than protons. 4 Nonetheless, comparable membrane conductivities have been shown. 5 Moreover, compared to liquid-based alkaline fuel cells, AEMFCs may confer a higher power density, may have the capacity to function with impurities in the fuel, and have the potential to operate in CO 2 -containing air, 2 especially under high current load. 6 Additionally, as most AEMFCs are hydrocarbon in nature, they may display a lower fuel crossover compared to perfluorosulfonate-based ionomers.A barrier to the development of AEMFC technology concerns the hydroxide-conducting polymer; namely, its poor chemical stability and low ion conductivity under typical fuel cell conditions. The same issue applies even more to the ionomer in the catalyst layer, which experiences rapid variations in hydration-state. In a typical anionexchange ionomer, both the polymer backbone and functional groups are subject to hydroxide attack, e.g., via β-Hoffman elimination or direct nucleophilic displacement of the functional groups.7,8 Cleavage of the polymer backbone primarily affects the mechanical properties of the membrane,...

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“…The results apparently indicate that the full-IPN structure brought on high tolerance of the membranes towards nucleophilic attack of hydroxide ions. The stability of the prepared membranes in strong alkaline solution at room temperature is better than that of the AEMs based on polybenzimidazolium hydroxides [66]. The formation of the full-IPN restricted the decrease in conductivity of the membranes.…”

Section: Stability Of the Full-ipn Membrane In Alkaline Solutionsmentioning

confidence: 87%

Formation and evaluation of interpenetrating networks of anion exchange membranes based on quaternized chitosan and copolymer poly(acrylamide)/polystyrene

Wang

2015

Solid State Ionics

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Polybenzimidazolium hydroxides – Structure, stability and degradation

Cited by 105 publications

References 27 publications

KOH-doped polybenzimidazole for alkaline direct glycerol fuel cells

KOH-doped polybenzimidazole for alkaline direct glycerol fuel cells

The Control and Effect of Pore Size Distribution in AEMFC Catalyst Layers

Formation and evaluation of interpenetrating networks of anion exchange membranes based on quaternized chitosan and copolymer poly(acrylamide)/polystyrene

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