High pressure electrical conductivity studies of acid doped polybenzimidazole

Fontanella, J. J.; Wintersgill, M. C.; Wainright, Jesse S.; Savinell, Robert F.; Litt, Morton H.

doi:10.1016/s0013-4686(97)10032-9

Cited by 167 publications

(80 citation statements)

References 16 publications

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“…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%. This is in accordance with previous results since PBI can be used with low humidification 6 while conductivity of SPSF, as stated above, is slightly dependent on relative humidity. As a result, the blends of PBI with SPSF could also be expected to be operational with low humidification.…”

Section: Resultssupporting

confidence: 93%

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

Hasiotis

Deimede

et al. 2001

J. Electrochem. Soc.

148

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Polymeric membranes from blends of sulfonated polysulfones ͑SPSF͒ and polybenzimidazole ͑PBI͒ 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 10 Ϫ3 S cm Ϫ1 . In the case of blends of PBI and SPSF it was found to be higher than 10 Ϫ2 S cm Ϫ1 . 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.

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Section: Resultssupporting

confidence: 93%

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

Hasiotis

Deimede

et al. 2001

J. Electrochem. Soc.

148

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“…That response is typical for the complex impedance of electrolytes with blocking electrodes. [36][37][38][39][40][41][42][43][44] An example from the present work, for which only the depressed semicircle was observed, is given in Fig. 1.…”

Section: Resultssupporting

confidence: 49%

Pressure and temperature variation of the electrical conductivity of poly(propylene glycol) containing LiCF3SO3

Fontanella

1999

The Journal of Chemical Physics

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Complex impedance and differential scanning calorimetry (DSC) studies have been carried out on poly(propylene glycol) with average molecular weight 1025 (PPG) and PPG containing LiCF3SO3. The impedance studies were made at frequencies from about 1 mHz to 100 MHz at pressures up to 0.3 GPa (3 kbar) over the temperature range 215–365 K. Both the impedance and DSC studies were carried out in vacuum or at atmospheric pressure over a temperature range of about 100–375 K. As a consequence, the impedance studies overlap the DSC glass transition temperature. The inadequacy of the widely used Vogel–Tammann–Fulcher or Williams–Landel–Ferry equations to describe the temperature variation of the vacuum electrical conductivity data is discussed. It is shown that the Bendler–Shlesinger formalism is a better representation of the data, particularly in the region close to the glass transition. The first pressure derivative of the electrical conductivity, and hence apparent activation volume, decreases strongly as temperature increases. In addition, the activation volumes are larger for the low molecular weight liquids than the values reported previously for related, high molecular weight rubbery electrolytes. Next, there appears to be an exponential relationship between the activation volume and the electrical conductivity. Finally, the pressure variation of the electrical conductance exhibits negative curvature which shows that the activation volume increases as pressure increases. A qualitative explanation of each of these results concerning the relationship between conductivity, temperature, and pressure is given in terms of free volume. However, whether free volume can provide a quantitative explanation remains to be determined.

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“…For phosphoric acid-doped PBI membranes, the proton conductivity has been measured by several groups. Fontanella et al [131] measured the conductivity of aciddoped PBI at compressions of up to 0.25 GPa. At room temperature the conductivity decreases with increasing pressure for both acid-doped PBI and 85% phosphoric acid, as expected due to the viscosity increase.…”

Section: Proton Conductivitymentioning

confidence: 99%

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

Jensen

Savinell

et al. 2009

Progress in Polymer Science

1,235

852

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. To achieve high temperature operation of proton exchange membrane fuel cells (PEMFC), preferably under ambient pressure, acid-base polymer membranes represent an effective approach. The phosphoric acid-doped polybenzimidazole membrane seems so far the most successful system in the field. It has in recent years motivated extensive research activities with great progress. This treatise is devoted to updating the development, covering polymer synthesis, membrane casting, physicochemical characterizations and fuel cell technologies. To optimize the membrane properties, high molecular weight polymers with synthetically modified or N-substituted structures have been synthesized. Techniques for membrane casting from organic solutions and directly from acid solutions have been developed. Ionic and covalent cross-linking as well as inorganic-organic composites has been explored. Membrane characterizations have been made including spectroscopy, water uptake and acid doping, thermal and oxidative stability, conductivity, electro-osmotic water drag, methanol crossover, solubility and permeability of gases, and oxygen reduction kinetics. Related fuel cell technologies such as electrode and MEA fabrication have been developed and high temperature PEMFC has been successfully demonstrated at temperatures of up to 200• C under ambient pressure. No gas humidification is mandatory, which enables the elimination of the complicated humidification system, compared with Nafion cells. Other operating features of the PBI cell include easy control of air flow rate, cell temperature and cooling. The PBI cell operating at above 150• C can tolerate up to 1% CO and 10 ppm SO 2 in the fuel stream, allowing for simplification of the fuel processing system and possible integration of the fuel cell stack with fuel processing units. Long-term durability with a degradation rate of 5 V h −1 has been achieved under continuous operation with hydrogen and air at 150-160• C. With load or thermal cycling, a performance loss of 300 V per cycle or 40 V h −1 per operating hour was observed. Further improvement should be done by, e.g. optimizing the thermal and chemical stability of the polymer, acid-base interaction and acid management, activity and stability of catalyst and more importantly the catalyst support, as well as the integral interface between electrode and membrane.

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High pressure electrical conductivity studies of acid doped polybenzimidazole

Cited by 167 publications

References 16 publications

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

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

Pressure and temperature variation of the electrical conductivity of poly(propylene glycol) containing LiCF3SO3

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

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