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Cited by 155Fuel Cells and Related MaterialsMembrane-based Ion Separation TechniquesAdvancements in Solid Oxide Fuel Cells

Development and Characterization of Acid-Doped Polybenzimidazole/Sulfonated Polysulfone Blend Polymer Electrolytes for Fuel Cells

Open access
Hasiotis, C., Qingfeng, Li, Deimede, V., Kallitsis, J. K., Kontoyannis, C. G., Bjerrum, N. J.·2001·Journal of The Electrochemical Society
DOI 10.1149/1.1366621
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Abstract

Polymeric membranes from blends of sulfonated polysulfones (SPSF) and polybenzimidazole (PBI) doped with phosphoric acid were developed as potential high-temperature polymer electrolytes for fuel cells and other electrochemical applications. The water uptake and acid doping of these polymeric membranes were investigated. Ionic conductivity of the membranes was measured in relation to temperature, acid doping level, sulfonation degree of SPSF, relative humidity, and blend composition. The conductivity of SPSF was of the order of In the case of blends of PBI and SPSF it was found to be higher than Much improvement in the mechanical strength is observed for the blend polymer membranes, especially at higher temperatures. Preliminary work has demonstrated the feasibility of these polymeric membranes for fuel-cell applications. © 2001 The Electrochemical Society. All rights reserved.

AI snapshot

Written from the paper’s full text.

TL;DR

Acid-doped blends of polybenzimidazole and sulfonated polysulfone were developed as high-temperature polymer electrolytes. The blends showed higher ionic conductivity than pure PBI and better mechanical strength at elevated temperature, with preliminary fuel-cell operation demonstrated.

Key findings

  • Water uptake was 20–21 wt % for pristine PBI (3.4–3.6 H₂O per repeat unit), 8–10 wt % for SPSF at 36% sulfonation (about 7 H₂O per sulfonate), and intermediate for blends (18–19 wt % for PBI-rich, 10–12 wt % for SPSF-rich). Acid doping increased with acid concentration, temperature, and PBI/SPSF ratio; pure PBI reached about 500 mol % H₃PO₄ with 9–11 M acid, while SPSF below 50% sulfonation stayed below 50 mol % unless directly doped.
  • SPSF conductivity was around 10⁻³ S cm⁻¹, while PBI-SPSF blends exceeded 10⁻² S cm⁻¹ and reached up to 7 × 10⁻¹ S cm⁻¹ at 160 °C with 2300 mol % doping. Relative humidity from 30 to 80% changed conductivity only slightly (about 2–5%); at 175 °C without humidification, conductivity stabilized after roughly 20 h at 2.1 × 10⁻² S cm⁻¹ for the blend and 1.9 × 10⁻² S cm⁻¹ for PBI.
  • At 150 °C and doping levels of about 450–660 mol % H₃PO₄, tensile stress was 58–115 kgf cm⁻² for 50–50 PBI-SPSF blends versus 25–62 kgf cm⁻² for pure PBI; no mechanical improvement was seen at room temperature.
  • A preliminary fuel cell using a 75% PBI–25% SPSF membrane (36% sulfonation, 455 mol % doping) at 190 °C with no humidification produced 650 mA/cm² at 0.5 V and over 0.3 W/cm², though with unoptimized electrodes.

Methods

  • SPSF was made by sulfonating polysulfone with chlorosulfonic acid, with sulfonation degree determined by ¹H NMR and FT-Raman. PBI/SPSF membranes were solution-cast from DMAc, pure SPSF from DMF, and dried at 190 °C under vacuum.
  • Water uptake and acid doping were measured by immersion in water or H₃PO₄ and weight changes; doping level was expressed as mol % H₃PO₄ per polymer repeat unit, with water separated by drying doped membranes at 110 °C under vacuum.
  • Conductivity was measured with a four-probe cell using current interruption under controlled temperature and humidity. Mechanical properties were tested by tensile stress, and a 5 cm² single fuel cell used Pt/C electrodes impregnated with PBI, hot-pressed at 150 °C, and operated without humidification.

Limitations

  • Stated: long-term operation data are needed to verify blend performance; doping above 1000 mol % H₃PO₄ is undesirable because mechanical strength becomes very low; direct doping of high-sulfonation SPSF gave brittle, nonhomogeneous membranes and no conductivity at 300 mol %; fuel-cell tests were preliminary with unoptimized electrodes.
  • Evident: literature conductivity values are scattered and not directly comparable due to differing conditions; no durability or CO-tolerance testing is reported; only a limited set of blend compositions and sulfonation degrees was examined.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1149/1.1366621

Cites

28 of 28 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

4 of 33 cited sources checked · 3 supported · 0 flagged · accuracy not yet measured

  • Findingown data

    Pure PBI membranes reached an acid doping level of about 500 mol% H3PO4 using 9-11 M phosphoric acid at room temperature, in agreement with other reports.

    “For pure PBI membranes ͑ᮀ͒, as can be seen from the figure, a doping level of around 500 mol % H 3 PO 4 can be achieved by using 9-11 M H 3 PO 4 solution at room temperature, which is in good agreement with other reports.3,6,9,12”
    Quote in the paperNot a substantial claim1 of 4 sources checked
    • cites [3] Wainright, 1995, J. Electrochem. Soc. source
    • cites [6] Fontanella, 1998, Electrochim. Acta source
    • cites [9] Wang, 1996, J. Electrochem. Soc. source

      The Experimental section (p. 1233) describes a PBI membrane doped with 5 mol H3PO4 per repeat unit, or 500 mol%. It does not say that this level was achieved using 9–11 M phosphoric acid at room temperature; its reference to 5 M acid concerns electrode impregnation, not membrane doping. (LLM, conf=0.87)

      Experimental — accuracy not yet measured
    • cites [12] Zecevic, 1997, J. Electrochem. Soc. source
    • The authors state this as an assumption: When acid-doped PBI membranes are dried at 110°C under vacuum, the mass lost is water and the mass that remains is polymer containing only phosphoric acid.
  • Premisecitation

    Water uptake by polymer membranes is essential for proton conductivity.

    “As suggested by Zawodzinski et al. 28,29 and Hinatsu et al., 30 the water uptake by the polymer membranes is essential for proton conductivity.”
    Quote in the paperNot a substantial claim3 of 3 sources checked
    • cites [28] Zawodzinski, 1993, J. Electrochem. Soc. source
    • cites [29] Zawodzinski, 1993, J. Electrochem. Soc. source
    • cites [30] Hinatsu, 1994, J. Electrochem. Soc. source
  • Findingown data

    Pristine PBI membranes immersed in distilled water at room temperature for several days absorbed up to 20-21 w/w% water, corresponding to 3.4-3.6 water molecules per PBI repeat unit.

    “By immersing PBI membranes in distilled water for several days at room temperature, it is found in the present work that up to 20-21 w/w % ͑with a dry polymer as basis͒ water can be absorbed by the pristine PBI membranes, corresponding to 3.4-3.6water molecules per repeat unit of PBI.”
    Quote in the paperNot a substantial claim
  • Findingown data

    For SPSF with sulfonation degree from 10% to 44%, conductivity depended only slightly on sulfonation degree.

    “In the studied range of the sulfonation degree ͑from 10 to 44%͒, a small dependence of conductivity on sulfonation degree of SPSF was observed, though a high conductivity was reported at much higher sulfonation degrees.20,21”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [20] Lufrano, 2000, J. Appl. Polym. Sci. source
    • cites [21] Poinsignon, 1999, Mater. Res. Soc. Symp. Proc. source
  • Findingown data

    Increasing the direct-doping level above 300 mol% H3PO4 produced nonhomogeneous SPSF membranes with patches of differing physical characteristics.

    “By increasing the doping level to more than 300 mol % H 3 PO 4 , nonhomogeneous membranes exhibiting patches of different physical characteristics ͑e.g., thickness, coloration, etc.͒, were obtained using the direct-doping procedure.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 16
  • The quote only partly states this claim. 1
  • Classified as probably not a substantial claim. 10

  • May combine two claims.

    Findingown data

    The doping level of PBI-SPSF blend membranes increased with higher acid concentration, higher temperature, and higher PBI/SPSF ratio.

    “It was found that the doping level increases upon increasing the acid concentration, temperature, and the PBI/SPSF ratio.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: When acid-doped PBI membranes are dried at 110°C under vacuum, the mass lost is water and the mass that remains is polymer containing only phosphoric acid.

  • May combine two claims.

    Findingreasoning

    SPSF polymers with high sulfonation degree are brittle and do not form freestanding films from solution or melt pressing.

    “These polymers have a brittle nature and therefore they do not form freestanding films either from solution or from melt pressing.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Dry SPSF membranes without pretreatment absorbed 8-10 w/w% water at room temperature, about seven water molecules per sulfonate group.

    “It is found that, at room temperature, 8-10 w/w % water is absorbed by the dry SPSF membranes, which have not experienced any pretreatment.This corresponds to about seven water molecules per sulfonate group.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    For PBI membranes in 7.0 and 9.7 M phosphoric acid, water uptake was 4.0 and 5.6 mol H2O per repeat unit, respectively.

    “For 7.0 and 9.7 M H 3 PO 4 , for example, the water uptake by PBI membranes is found to be 4.0 and 5.6 mol H 2 O, respectively.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: When acid-doped PBI membranes are dried at 110°C under vacuum, the mass lost is water and the mass that remains is polymer containing only phosphoric acid.

  • May combine two claims.

    Findingown data

    The ionic conductivity of PBI-SPSF blend membranes is greater than 10^-2 S cm^-1 and increases with temperature.

    “-The conductivity of blends was found to be higher than 10 Ϫ2 S cm Ϫ1 and increase with temperature.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    At a doping level of about 450-660 mol% H3PO4, the tensile stress of pure PBI membranes is 25-62 kgf cm^-2, while that of 50-50 mol% PBI-SPSF blends is 58-115 kgf cm^-2.

    “At a doping level of about 450-660 mol % H 3 PO 4 , for example, the tensile stress for pure PBI membranes is in a range of 25-62 kgf cm Ϫ2 , while for 50-50 mol % PBI-SPSF blends it is as high as 58-115 kgf cm Ϫ2 .”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In a fuel-cell test at 0.5 V, a current density of 650 mA/cm2 was obtained, corresponding to a power density over 0.3 W/cm2.

    “At a cell voltage of 0.5 V, a current density of 650 mA/cm 2 was obtained, corresponding to a power density of over 0.3 W/cm 2 .”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The Arrhenius activation energy for ionic conductivity of acid-doped SPSF membranes is 12.8-14.8 kJ/mol in the 298-363 K range and 6.1-6.7 kJ/mol in the 363-433 K range.

    “The slopes of the Arrhenius plots of conductivity between 298-363 and 363-433 K ͑not shown͒ give the activation energy of 12.8-14.8and 6.1-6.7 kJ/mol, respec- tively.”
    Quote in the paperSubstantial claim

  • The quote only partly states this claim.

    Findingown data

    For acid-doped SPSF membranes, ionic conductivity rises linearly with temperature in two separate ranges, approximately 298-363 K and 363-433 K.

    “As shown in Fig. 3, there are two regions where the conductivity increases linearly with temperature.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Relative humidity does not significantly affect the ionic conductivity of PBI-SPSF blends; increasing RH from 30% to 80% raises conductivity by only about 3-5%.

    “Relative humidity does not seem to influence significantly the conductivity of blends since a ϳ3-5% increase in ionic conductivity was recorded when the relative humidity was gradually increased from 30 to 80%.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Acid-doped PBI-SPSF blend membranes exhibit ionic conductivity over 10^-2 S cm^-1, which is higher than pure PBI membranes under the same doping conditions.

    “The acid-doped PBI-SPSF blend membranes exhibit ionic conductivity over 10 Ϫ2 S cm Ϫ1 , which is higher than pure PBI membranes under the same doping conditions.”
    Quote in the paperSubstantial claim

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

    Premisecitation

    SPSF water uptake increases with sulfonation degree or ion-exchange capacity, and ion-exchange capacity increases linearly with sulfonation degree.

    “It has been observed that the water uptake of the SPSF increases with the sulfonation degree or the ion-exchange capacity, 20,21 the latter being found to increase linearly with the sulfonation degree.20”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [20] Lufrano, 2000, J. Appl. Polym. Sci. source
    • cites [21] Poinsignon, 1999, Mater. Res. Soc. Symp. Proc. source

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

    Premisecitation

    Sulfonating polysulfone raises its glass transition temperature above 200°C.

    “It has been reported that sulfonation of polysulfone increases the glass transition temperature to higher than 200°C.24,25”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [24] Deimede, 2000, Macromolecules source
    • cites [25] Brousse, 1976, Desalination source

  • May combine two claims.

    Premisecitation

    PBI-rich PBI/SPSF blends appear to be a single-phase system, while SPSF-rich blends show two phases.

    “In general, PBI-rich blends appear to be one compound system, as opposed to the SPSF rich blends where two phases were observed.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [24] Deimede, 2000, Macromolecules source

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

    Premisecitation

    SPSF conductivity increases exponentially as sulfonation degree increases.

    “Actually, the conductivity of SPSF was found to increase exponentially with the increase of sulfonation degree.20”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [20] Lufrano, 2000, J. Appl. Polym. Sci. source

  • May combine two claims.

    Interpretationown data

    The increase in conductivity with sulfonation degree implies that both acid-doped PBI and sulfonate sites of SPSF participate in conduction.

    “This behavior is illustrated in Fig. 5 and implies that not only the acid-doped PBI but also sulfonate sites of SPSF are involved in the conduction mechanism.”
    Quote in the paperSubstantial claim

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

    Interpretationreasoning

    The activation-energy change observed near 90°C may be due to a phase transition of water at elevated temperatures.

    “The change of the activation energy, which occurs at ϳ90°C, might be attributed to the phase transition of water at elevated temperatures.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    For sulfonated polysulfone at IEC 0.98 mequiv/g (sulfonation degree about 43%), Brousse et al. reported tensile stress of 1100 kgf cm^-2 dry and 330 kgf cm^-2 wet.

    “For the sulfonated polysulfone at IEC of 0.98 mequiv/g ͑sulfonation degree about 43%͒, Brousse et al. reported a tensile stress of 1100 and 330 kgf cm Ϫ2 for the dry and wet polymer, respectively.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Brousse et al.

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

  • May combine two claims.

    Interpretationcitation

    The fuel-cell performance of the blend membrane was achieved with unoptimized electrodes and is comparable to that of pure PBI.

    “This performance is achieved with unoptimized electrodes and is comparable to that of pure PBI.8,14”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [8] Li Qingfeng, H. A. Hjuler, and N. J. Bjerrum,J. Appl. Electrochem., Accepted for publication (2001).

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

    • cites [14] Wang, 1996, Electrochim. Acta source

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

    Premisecitation

    Fontanella et al. obtained a conductivity of 4.5×10^-5 S cm^-1 for dry PBI doped with 600 mol% H3PO4 at room temperature.

    “Fontanella et al. 6 obtained a conductivity of 4.5 ϫ 10 Ϫ5 S cm Ϫ1 for dry PBI doped with 600 mol % H 3 PO 4 at room temperature.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [6] Fontanella, 1998, Electrochim. Acta source

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

    Premisecitation

    Bouchet et al. reported an anhydrous conductivity of 7×10^-6 S cm^-1 at 30°C and doping level of 305 mol% H3PO4 for anhydrous PBI/H3PO4 mixtures.

    “Using anhydrous mixtures of PBI and H 3 PO 4 , Bouchet et al. 5 reported an anhydrous conductivity of 7 ϫ 10 Ϫ6 S cm Ϫ1 at a temperature of 30°C and doping level of 305 mol % H 3 PO 4 .”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [5] Bouchet, 1999, Solid State Ionics source

  • May combine two claims.

    Premisecitation

    The elongation at break for polysulfone is reported to be 50-100%, compared with 1.8-3.0% for PBI.

    “The elongation at break for polysulfone, for example, is reported to be 50-100%, compared to 1.8-3.0%for PBI. 31”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [31] Specialty Polymers, R. W. Dyson, Editor, Blackie Academic & Professional, London (1998).

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

  • Classified as probably not a substantial claim.

    Interpretationreasoning

    The higher conductivity of PBI-SPSF blends may be due to interactions between H3PO4/H2O and sulfonate groups of SPSF as well as between H3PO4 and N-H groups of PBI.

    “This might be attributed to the interaction not only between H 3 PO 4 and the N-H groups of PBI, but also between H 3 PO 4 /H 2 O and the sulfonate groups of SPSF.”
    Quote in the paperSubstantial claim

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

    Interpretationcitation

    PBI's affinity for moisture may be due to intermolecular hydrogen bonding between its N and N-H groups and water.

    “This is possibly due to an intermolecular hydrogen bonding between N and N-H groups in PBI and water.27”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [27] Chung, 1997, Rev. Macromol. Chem. Phys.

      Not checked in the free run.

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

    Premisecitation

    Wainright et al. found that the conductivity of PBI at the same temperature and doping level increases with water vapor activity up to 3×10^-2 S cm^-1 at 0.2 pH2O/psat.

    “They also found that the conductivity of PBI, at the same temperature and doping level, increases with water vapor activity up to 3 ϫ 10 Ϫ2 S cm Ϫ1 at 0.2 p H 2 O /p sat .”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] Wainright, 1995, J. Electrochem. Soc. source

  • May combine two claims.

    Interpretationreasoning

    In this work, both phosphoric acid and sulfonate-water clusters act as conducting species in the acid-doped SPSF membranes.

    “Consequently, both phosphoric acid and sulfonate-water clusters are the conducting active species.”
    Quote in the paperSubstantial claim
26 of 26

  • The authors state this as an assumption.

    When acid-doped PBI membranes are dried at 110°C under vacuum, the mass lost is water and the mass that remains is polymer containing only phosphoric acid.

    “The weight loss is assumed to be due to the water uptake and the remaining weight is assumed to be the polymer purely doped with the acid.”

  • The paper relies on this without support.

    Cast SPSF membranes have good mechanical strength, flexibility, and low gas permeability.

    “The cast membranes of sulfonated polysulfones ͑SPSF͒ exhibit good mechanical strength, flexibility, and low gas permeability.”

  • The paper relies on this without support.

    SPSF is inexpensive and therefore lowers the cost of the electrolyte.

    “Besides, SPSF is a quite inexpensive polymeric material that results in lowering the cost of electrolyte.”

  • The paper relies on this without support.

    Proton conduction requires an electrolyte-active species dispersed in the polymer structure.

    “An electrolyte active species dispersed within the polymer structure is a necessity for proton conduction.”

  • The paper relies on this without support.

    Polysulfone has excellent mechanical properties.

    “On the other hand, polysulfone exhibits excellent mechanical properties.”

  • The paper relies on this without support.

    These polymeric materials become conductive after doping with an acid.

    “These polymeric materials are conductive after doping with an acid.”

  • The paper relies on this without support.

    At temperatures above 150°C, managing water inside the membrane over long periods may be difficult, which may reduce ionic conductivity.

    “At high temperatures ͑Ͼ150°C͒ difficulty of the management of water inside the membrane for a long period of time might appear, and as a result the ionic conductivity of the polymer electrolytes might decrease.”

  • The paper relies on this without support.

    Long-term performance is essential for any application of the membranes to a PEMFC.

    “The question which arises from this speculation is whether the high conductivity of blends can be kept constant for a long time, since a long-term performance is essential for any application of the membranes to a PEMFC.”

  • The paper relies on this without support.

    Operating a PEMFC without humidifying the gases is desirable because it simplifies the cell system.

    “Besides, the operation of a PEMFC without any humidification of gases is desired because it simplifies the construction of the cell system.”
9 of 9

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Figure 6 blend has two stated sulfonation degrees

    Minor

    The discussion identifies the SPSF sulfonation degree of the Figure 6 membranes as 36%, but the Figure 6 caption specifies 20% for both blend compositions.

  • Catalyst loading differs between the text and Figure 10 caption

    Minor

    The fuel-cell test is described with a platinum loading of 0.45 mg/cm2 per electrode, while the caption for its performance curve gives 0.48 mg/cm2 per electrode.

  • Figure 6 uses conflicting SPSF sulfonation degrees

    Minor

    The discussion describes the Figure 6 blends as having 36% SPSF sulfonation, whereas its caption specifies 20% for both blend compositions.

  • Pure SPSF sulfonation dependence is both reported and denied

    Minor

    The results say a small dependence of pure SPSF conductivity on sulfonation degree was observed, but a later passage says this dependence was not studied in the present work.

4 of 4

Cites

Flagged first, then by citations

Research works printed but not linked: 2

  1. Wang, 1996, J. Appl. Electrochem., 26, 751
  2. Chung, 1997, Rev. Macromol. Chem. Phys., C37, 277

Cited by

Sorted by citations

Related

Authors
Hasiotis, C., Qingfeng, L., Deimede, V., Kallitsis, J. K., Kontoyannis, C. G., & Bjerrum, N. J.
Affiliations
  • FORTH Institute of Chemical Engineering Sciences (GR)
  • University of Patras (GR)
  • Technical University of Denmark (DK)
ORCID
Venue
Journal of The Electrochemical Society
Publisher
The Electrochemical Society
Published
2001
Volume
148
Issue
5
Pages
A513
ISSN
0013-4651 (ISSN-L)
DOI
10.1149/1.1366621
OpenAlex
W2034181826
Cited by
155
References
28
Citations by year
2026: 2 · 2025: 1 · 2024: 2 · 2023: 1 · 2022: 5 · 2021: 6 · 2020: 2 · 2019: 4 · 2018: 6 · 2017: 5 · 2016: 5 · 2015: 10 · 2014: 6 · 2013: 7 · 2012: 10
FWCI
8.40
Type
journal article
Language
en
Open access
Locations
  • Journal of The Electrochemical Society (publishedVersion)
  • Technical University of Denmark, DTU Orbit (Technical University of Denmark, DTU) (submittedVersion, other-oa)
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
polybenzimidazole, sulfonated polysulfone, polymer electrolyte membranes, blend membranes, phosphoric acid doping, ionic conductivity, high-temperature fuel cells, water absorption

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