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Cited by 75Fuel Cells and Related MaterialsMembrane-based Ion Separation TechniquesAdvancements in Solid Oxide Fuel Cells

Acid–base blend membranes consisting of sulfonated poly(ether ether ketone) and 5-amino-benzotriazole tethered polysulfone for DMFC

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Li, W., Manthiram, A., Guiver, M.D.·2010·Journal of Membrane Science
DOI 10.1016/j.memsci.2010.06.059
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Crossref · 10.1016/j.memsci.2010.06.059

Cites

47 of 47 references verified0 citation errors · 0 not checkable

Statistics

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Claims the paper makes

5 of 29 cited sources checked · 3 supported · 0 flagged · accuracy not yet measured

  • Findingreasoning

    Despite lower IEC values caused by acid-base interactions, SPEEK/PSf-BTraz membranes conduct protons better than plain SPEEK.

    “Compared to some blend membrane systems based on acid-base interactions that have been investigated in the literature [18,19,31,32], the SPEEK/PSf-BTraz blend membranes presented here show higher proton conductivity than plain SPEEK membrane despite a decrease in the IEC values due to acid-base interactions.”
    Quote in the paperSubstantial claim1 of 4 sources checked
    • cites [18] Jörissen, 2002, New membranes for direct methanol fuel cells, J. Power Sources source
    • cites [19] Kerres, 2005, Blended and cross-linked ionomer membranes for application in membrane fuel cells, Fuel Cells source
    • cites [31] Wycisk, 2005, Sulfonated polyphosphazene-polybenzimidazole membranes for direct methanol fuel cells, J. Electrochem. Soc. source
    • cites [32] Wycisk, 2006, Direct methanol fuel cell membranes from Nafion-polybenzimidazole blends, J. Power Sources source
  • Premisecitation

    The pKa values of the heterocycles can influence the proton conductivity of this type of blend membrane.

    “Additionally, as we reported before [22], the pK a values of the heterocycles could also influence the proton conductivity of this type of blend membranes.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [22] Li, 2009, Blend membranes consisting of sulfonated poly(ether ether ketone) and polysulfone bearing 4-nitro-benzimidazole for direct methanol fuel cells, J. Electrochem. Soc. source
  • Findingown data

    Blend membranes' measured IEC values fall below values calculated from the amounts of acidic and basic polymers.

    “Based on the data in Table 1, the measured IEC values of the blend membranes are lower than those calculated from the concentration of the acidic and basic polymers.”
    Quote in the paperSubstantial claim
  • Findingown data

    FTIR spectra show that BTraz groups are attached to PSf.

    “The strong absorption band of the C N stretching at 1580 cm -1 and the broad absorption of the isolated N-H stretching around 3400 cm -1 distinguish the PSf-BTraz from the CPSf precursor, indicating the attachment of BTraz groups onto PSf.”
    Quote in the paperSubstantial claim
  • Findingreasoning

    All blend membranes have lower IEC values than plain SPEEK membrane.

    “Since the acid-base interaction between the sulfonic acid and heterocycle groups reduces the number of dissociable H + ions from the sulfonic acid groups, all blend membranes show lower IEC values than plain SPEEK membrane.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 2
  • May combine two claims. 22

  • Classified as probably not a substantial claim.

    Premisecitation

    At equal humidity, conductivity measured in-plane typically exceeds through-plane conductivity by a factor of 2.5 to 5.

    “It has been reported that the in-plane proton conductivity is usually 2.5-5 times higher than the through-plane conductivity when measured at the same humidity condition [29,30].”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [29] Ma, 2006, Anisotropic conductivity over in-plane and thickness directions in Nafion-117, J. Electrochem. Sci. source

      The Abstract and p. A2277 report in-plane conductivity 2.5–5 times through-plane conductivity for Nafion-117 membranes hot-pressed at 150°C under 1200 or 600 kgf/cm², respectively. The Abstract also says there was no through-plane conductivity decrease relative to in-plane conductivity at 0 kgf/cm², so the source does not support presenting that ratio as the usual result regardless of pretreatment. (LLM, conf=0.91)

      Experimental — accuracy not yet measured
    • cites [30] Soboleva, 2008, Investigation of the through-plane impedance technique for evaluation of anisotropy of proton conducting polymer membranes, J. Electroanal. Chem. source

  • May combine two claims.

    Interpretationcitation

    Blend membranes' reduced methanol crossover stems from their lower swelling and IEC relative to plain SPEEK, which arise from ionic cross-linking via acid-base interaction.

    “Also, as reported for other acid-base blend membranes, the lower methanol crossover in the blend membranes is due to the lower swelling and lower IEC compared to the plain SPEEK membrane as a result of the ionic cross-linking through acid-base interaction in the blend membranes [31,32].”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [31] Wycisk, 2005, Sulfonated polyphosphazene-polybenzimidazole membranes for direct methanol fuel cells, J. Electrochem. Soc. source

      The Results and Discussion report that acid–base cross-links in SPOP–PBI blends reduce effective IEC, while p. A894 reports reduced swelling and methanol permeability as PBI content increases. The paper studies SPOP–PBI, not a comparison with plain SPEEK, so it does not support that specific comparator or establish the stated cause of a SPEEK blend’s lower crossover. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [32] Wycisk, 2006, Direct methanol fuel cell membranes from Nafion-polybenzimidazole blends, J. Power Sources source
    • Rests on an assumption: BTraz is more hydrophobic than sulfonic acid groups.

  • May combine two claims.

    Interpretationcitation

    Inserting heterocycles into the ionic clusters formed by sulfonic acid groups could widen proton transfer channels and enhance the vehicle mechanism.

    “Moreover, the insertion of the heterocycles into the ionic clusters formed by the sulfonic acid groups could broaden the proton transfer channels [22,23], resulting in an enhancement in the vehicle mechanism.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [22] Li, 2009, Blend membranes consisting of sulfonated poly(ether ether ketone) and polysulfone bearing 4-nitro-benzimidazole for direct methanol fuel cells, J. Electrochem. Soc. source
    • cites [23] Li, 2009, Blend membranes consisting of sulfonated poly(ether ether ketone) and 1H-perimidine tethered polysulfone for direct methanol fuel cells, Electrochem. Solid-State Lett. source

  • May combine two claims.

    Findingreasoning

    Under anhydrous conditions, raising temperature lowers proton conductivity for Nafion 115 and SPEEK but raises it for SPEEK/PSf-BTraz blend membranes.

    “While the proton conductivity of Nafion 115 and SPEEK decrease with increasing temperature due to the decreasing amount of proton carriers (water), the proton conductivities of the SPEEK/PSf-BTraz blend membranes increase.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    PSf-BTraz was synthesized and characterized.

    “Polysulfone tethered with 5-amino-benzotriazole (PSf-BTraz) has been synthesized and characterized.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    The SPEEK/PSf-PImd blend membrane has OCV values 0.05 V higher than plain SPEEK and 0.11 V higher than Nafion 115.

    “the SPEEK/PSf-PImd blend membrane shows OCV values 0.05 and 0.11 V higher than those of, respectively, plain SPEEK and Nafion 115 membranes.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    Although blend membranes have larger ionic cluster size than plain SPEEK, they show lower methanol crossover.

    “More interestingly, even though the blend membranes show larger ionic cluster size than plain SPEEK, they exhibit lower methanol crossover”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The maximum power density of the SPEEK/PSf-BTraz-158 blend membrane is twice that of Nafion 115 and 1.8 times that of SPEEK at 80°C with 1 M methanol.

    “the maximum power density offered by the SPEEK/PSf-BTraz-158 blend membrane (174 mW/cm 2 ) is twice of that of the Nafion 115 membrane (84 mW/cm 2 ) and 1.8 times of that of the SPEEK membrane (97 mW/cm 2 )at80 • C with 1 M methanol solution.”
    • Also stated in: § 4. Conclusions · plain
      “The maximum power density of the blend membrane (with optimized PSf-BTraz contents) is 2 and 1.8 times higher than that of, respectively, Nafion 115 and plain SPEEK membranes at 80 • C with 1 M methanol feed.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Covalent and ionic cross-linking effectively controls dimensional stability and reduces methanol crossover in high-DS aromatic polymer membranes without greatly sacrificing proton conductivity.

    “Covalent and ionic cross-linking is found to be an effective way to control the dimensional stability and suppress methanol crossover of aromatic polymer membranes with high DS without unduly sacrificing the proton conductivity [11].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [11] Kerres, 2001, Development of ionomer membranes for fuel cells, J. Membr. Sci. source
    • Rests on an assumption: A high degree of sulfonation, needed for high proton conductivity, often increases membrane swelling and reduces mechanical stability.

  • May combine two claims.

    Premisereasoning

    More attention is being given to ionically cross-linked blend systems such as SPPO/PBI, SPEEK/PBI, and SPSf/aminated PSf because they are more flexible.

    “Because of this reason, more attention is being directed towards the development of ionomer networks containing ionically cross-linked blend systems such as SPPO (poly(2,6-dimethyl-1,4-phenylene oxide))/PBI (polybenzimidazole respectively), SPEEK/PBI, and SPSf/aminated PSf, which are more flexible [16][17][18][19].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [16][17][18][19]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • Rests on an assumption: Covalently cross-linked polymers tend to become brittle when dry, which is a serious problem for fuel cell use.

  • May combine two claims.

    Premisecitation

    Membranes made from acid-base interactions between SPEEK's sulfonic acid groups and PSf-tethered N-heterocycles (BIm, ABIm, NBIm, PImd) outperform plain SPEEK in DMFC because methanol crossover is reduced and proton conductivity is increased.

    “Our group reported recently [20][21][22][23] that blend membranes based on acid-base interactions between the sulfonic acid groups of SPEEK and the N-heterocycle groups (benzimidazole (BIm), amino-benzimidazole (ABIm), nitrobenzimidazole (NBIm), and 1H-perimidine (PImd)) tethered to PSf show improved DMFC performance compared to plain SPEEK membranes due to both suppressed methanol crossover and”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [20][21][22][23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • Rests on an assumption: The blend membrane concept uses industrially available, inexpensive PEEK and PSf precursors that are compatible because of their similar aromatic backbones.

  • May combine two claims.

    Premisecitation

    Aromatic polymers' sulfonic acid groups are less acidic (pKa about -1) than Nafion's (pKa about -6), which gives lower proton conductivity.

    “However, the lower acidity of the sulfonic acid groups in aromatic polymers (pK a ∼-1) compared to that of Nafion (pK a ∼-6) results in comparatively lower proton con-ductivity [10].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [10] Kreuer, 2001, On the development of proton conducting polymer membranes for hydrogen and methanol fuel cells, J. Membr. Sci. source

  • May combine two claims.

    Interpretationown data

    The better DMFC performance of the blend membranes comes from increased proton conductivity and reduced methanol crossover.

    “The blend membranes exhibit superior performance in direct methanol fuel cells (DMFC) compared to plain SPEEK and Nafion 115 membranes due to enhanced proton conductivity and much suppressed methanol crossover while preserving good swelling stability.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Aromatic polymers bearing sulfonic acid groups, including SPEEK, SPSf, and SPI, have been widely studied as Nafion replacements in DMFC because they are cheaper, thermally stable, mechanically strong, and resist hydrolysis and oxidation.

    “Several aromatic polymers with attached sulfonic acid groups such as sulfonated poly(ether ether ketone) (SPEEK), sulfonated polysulfone (SPSf), and sulfonated polyimide (SPI) have been widely investigated as candidates to substitute for the Nafion membrane in DMFC due to their lower cost, high thermal stability, good mechanical properties, and excellent resistance to hydrolysis and oxidation [4][”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [4][5][6][7][8][9]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning

    The higher BTraz content in PSf-BTraz-158 relative to PSf-BTraz-103 may enhance proton conductivity and further suppress methanol crossover via stronger acid-base interaction.

    “The higher BTraz content in PSf-BTraz-158 compared to that in PSf-BTraz-103 could enhance proton conductivity and suppress methanol crossover further through a stronger acid-base interaction.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The highest proton conductivity and electrochemical performance of SPEEK/PSf-BTraz are due to easiest proton transfer through 5-amino-benzotriazole groups and the lowest pKa (highest acidity) of BTraz compared with other N-heterocycles.

    “The SPEEK/PSf-BTraz blend membrane shows the highest proton conductivity and electrochemical performance due to the easiest proton transfer through the 5-amino-benzotriazole groups and the lowest pK a value (highest acidity) of the BTraz group compared to those of the other N-heterocycles investigated here.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Lower methanol crossover suppresses cathode catalyst poisoning and lowers the mixed potential at the cathode, raising the steady-state OCV.

    “The lower methanol crossover suppresses the cathode catalyst poisoning and lowers the mixed potential at the cathode, resulting in an increase in the OCV at steady-state.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    BTraz-containing blend membranes show less methanol crossover than BIm-containing ones, hinting that tethered N-heterocycle size can adjust methanol permeability in these acid-base blends.

    “Moreover, the lower methanol crossover of the blend membranes containing the BTraz groups compared to those containing the BIm groups (Table 3) may suggest that the size of the tethered N-heterocycle groups could play a role in tuning the methanol permeability property of this type of acid-base blend membranes.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The higher proton conductivity of SPEEK/PSf-NBIm relative to SPEEK/PSf-BIm is because NBIm has a lower pKa than BIm due to the electron-withdrawing nitro group on BIm.

    “as the pK a value of NBIm is lower than that of BIm due to the electron-withdrawing effect of the nitro functional group attached to BIm.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    The improved DMFC performance of the blend membranes relative to plain SPEEK results from their higher proton conductivity and lower methanol crossover.

    “The blend membranes show better performance in DMFC than plain SPEEK membrane due to higher proton conductivity (Table 1) and lower methanol crossover.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    PSf-BTraz helps enhance proton conduction and block methanol crossover.

    “the blend membranes exhibit much better performance than Nafion 115, confirming the assistance of PSf-BTraz in enhancing the proton conduction and blocking methanol crossover.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Because blend membranes have higher proton conductivity and lower methanol crossover than plain SPEEK, they all show higher maximum power density in DMFC than plain SPEEK and Nafion 115.

    “Since the blend membranes show increased proton conductivity and suppressed methanol crossover than plain SPEEK, they all show higher maximum power density in DMFC compared to plain SPEEK and Nafion 115 membranes.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The superior fuel cell performance of blend membranes over plain SPEEK and Nafion is due to enhanced proton conductivity and suppressed methanol crossover from acid-base interaction while maintaining good swelling properties.

    “The superior fuel cell performance of the blend membranes compared to the plain SPEEK and Nafion membranes is due to the enhanced proton conductivity and suppressed methanol crossover facilitated by the acid-base interaction, while maintaining good swelling property.”
    Quote in the paperSubstantial claim
23 of 23

  • The paper relies on this without support.

    Commercializing DMFC technology is hindered by high methanol permeability through current Nafion membranes and by slow methanol oxidation and oxygen reduction reactions.

    “However, the commercialization of the DMFC technology is hampered by the high methanol permeability through the currently used Nafion membranes as well as the sluggish methanol oxidation and oxygen reduction reactions.”

  • The paper relies on this without support.

    The stiffer aromatic backbones of these polymers may reduce methanol crossover because their ionic clusters are smaller than those in Nafion, which has a flexible PTFE backbone.

    “More importantly, the more rigid aromatic polymer backbones in these polymers could lower methanol crossover due to the smaller ionic cluster size compared to that in Nafion membrane, which has a flexible polytetrafluoroethylene (PTFE) backbone.”

  • The paper relies on this without support.

    A high degree of sulfonation, needed for high proton conductivity, often increases membrane swelling and reduces mechanical stability.

    “In order to maximize the proton conductivity, a high degree of sulfonation (DS) is desired, which often causes an increase in membrane swelling and degradation in mechanical stability.”

  • The paper relies on this without support.

    Covalently cross-linked polymers tend to become brittle when dry, which is a serious problem for fuel cell use.

    “However, covalently cross-linked polymers have a tendency to become brittle in the dry state, which is a critical problem for fuel cell application.”

  • The paper relies on this without support.

    The blend membrane concept uses industrially available, inexpensive PEEK and PSf precursors that are compatible because of their similar aromatic backbones.

    “This blend membrane concept is based on industrially available, inexpensive polymer precursors like PEEK 0376-7388/$ -see front matter © 2010 Elsevier B.V. All rights reserved.doi:10.1016/j.memsci.2010.06.059 and PSf, which are compatible with each other due to their similar aromatic backbones.”

  • The paper relies on this without support.

    Methanol crossover is a critical factor for long-term DMFC operation and strongly affects overall DMFC performance.

    “Methanol crossover is a critical parameter for long-term DMFC operation and has a significant effect on the overall performance of DMFC.”

  • The paper relies on this without support.

    BTraz is more hydrophobic than sulfonic acid groups.

    “As BTraz is more hydrophobic than the sulfonic acid groups, the PSf-BTraz basic polymer shows much lower water swelling compared to SPEEK in both water and water/methanol solution.”
7 of 7

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Authors
Li, W., Manthiram, A., & Guiver, M. D.
Affiliations
  • The University of Texas at Austin (US)
  • National Research Council Canada (CA)
Corresponding author
Manthiram, A.
ORCID
Venue
Journal of Membrane Science
Publisher
Elsevier BV
Published
2010-10
Volume
362
Issue
1-2
Pages
289-297
ISSN
0376-7388 (ISSN-L)
DOI
10.1016/j.memsci.2010.06.059
OpenAlex
W2004182431
Semantic Scholar
7030855459a00685f322edce881bd6f86299549b
Cited by
75
References
45
Citations by year
2025: 3 · 2024: 2 · 2022: 1 · 2021: 5 · 2020: 10 · 2019: 3 · 2018: 4 · 2017: 4 · 2016: 4 · 2015: 11 · 2014: 4 · 2013: 9 · 2012: 8
FWCI
5.96
Type
journal article
Language
en
Open access
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
  • Journal of Membrane Science (publishedVersion)
  • NPARC (submittedVersion)
Funders
  • Multidisciplinary University Research Initiative
  • Office of Naval Research (N00014-07-1-0758, N00014)
Topics
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Fuel Cells and Related Materials
  • Physical Sciences › Engineering › Biomedical Engineering › Membrane-based Ion Separation Techniques
  • Physical Sciences › Materials Science › Materials Chemistry › Advancements in Solid Oxide Fuel Cells
Keywords
sulfonated poly(ether ether ketone), polysulfone, direct methanol fuel cells, proton exchange membranes, proton conductivity, ion exchange capacity, Nafion 115 comparison

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