Conductivity of PBI Membranes for High-Temperature Polymer Electrolyte Fuel Cells

Ma, Yining; Wainright, Jesse S.; Litt, Morton H.; Savinell, Robert F.

doi:10.1149/1.1630037

Cited by 704 publications

(537 citation statements)

References 40 publications

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“…This indicates there is a strong dependence of polymerization process on both doping level and conductivity, and is reiterated by Bai and Ho in their work. 33 Typical doping levels reported in the literature for m-PBI prepared via the conventional organic solvent route are between 6 and 10 mol PA/PBI, 14,15,[17][18][19][20][21] although some films with higher doping levels and poor mechanical properties have been achieved. 52 Average doping levels for s-PBI membranes developed in this work are between 30 and 35 mol PA/PBI, although some membranes retain 40-50 mol PA/PBI.…”

Section: Resultsmentioning

confidence: 99%

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Sulfonated Polybenzimidazoles for High Temperature PEM Fuel Cells

2010

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High molecular weight, highly PA-doped s-PBI membranes have been developed with robust mechanical properties and excellent proton conductivities (>0.1 S cm -1 ) at elevated temperatures (>100°C). These membranes show high PA loadings of 30-35 mol PA/PBI, and average tensile stress and strain of 0.804 MPa and 69.64%, respectively. Proton conductivities were dependent on the acid doping level and measured between 0.1 and 0.25 S cm -1 at 180°C, a pronounced increase over most phosphoric acid-doped sulfonated PBI membranes to date. Preliminary fuel cell testing with hydrogen fuel and air or oxygen oxidants was performed at temperatures greater than 100°C without external feed gas humidification and show excellent performance (0.62-0.68 V at 0.2 A cm -2 and 160°C, hydrogen/air; 0.69-0.76 V at 0.2 A cm -2 and 160°C, hydrogen/oxygen). Initial performance stability studies were conducted for ∼3000 h and indicate great promise as high temperature membranes, with a degradation rate of 30 μV h -1 .

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Section: Resultsmentioning

confidence: 99%

“…After approximately two hours, the solution was a uniform blue-green color and all polymer had dissolved. A 5 mL aliquot was removed at various time intervals (20,24,27,46,53, and 92 h) and quenched in ice water. Once quenched, the polymer was washed with ice water until a neutral pH was reached.…”

Section: Methodsmentioning

confidence: 99%

Sulfonated Polybenzimidazoles for High Temperature PEM Fuel Cells

2010

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“…The presence of free PA at a high doping level has been observed by several authors in phosphoric acid doped PBI membranes using various techniques. 7,9,44 The very low intensity of the signal shows that the large majority of PA molecules are interacting with the polymer chains, i.e. hydrogen bonds between the protonated imidazole rings in the polymer chain and the phosphoric acid molecules occur.…”

Section: Phosphoric Acid Doped Ab-pbimentioning

confidence: 99%

Raman study of the polybenzimidazole–phosphoric acid interactions in membranes for fuel cells

Conti

Majerus

Noto

et al. 2012

Phys. Chem. Chem. Phys.

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Poly(2,5-benzimidazole) (AB-PBI) membranes are investigated by studying the FT-Raman signals due to the benzimidazole ring vibration together with the C-C and C-H out-of-and in-plane ring deformations. By immersion in aqueous ortho-phosphoric acid for different time periods, membranes with various doping degrees, i.e. different molar fractions of acid, are prepared. The chemical-physical interactions between polymer and acid are studied through band shifting and intensity change of diagnostic peaks in the 500-2000 cm À1 spectral range. The formation of hydrogen bonding networks surrounding the polymer seems to be the main reason for the observed interactions. Only if the AB-PBI polymer is highly doped, the Raman spectra show an additional signal, which can be attributed to the presence of free phosphoric acid molecules in the polymer network. For low and intermediate doping degrees no evidence for free phosphoric acid molecules can be seen in the spectra. The extent of the polymer-phosphoric acid interactions in the doped membrane material is reinvestigated after a period of one month and the stability discussed. Our results provide insight into the role of phosphoric acid as a medium in the conductivity mechanism in polybenzimidazole.

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“…To express the proton conductivity σ of acid doped PBI at different temperatures a modified Arrhenius equation has been suggested for polymer/acid (salt) complexes [57][58][59][60][61] …”

Section: Conductivity and Ir Lossesmentioning

confidence: 99%

A High Temperature Polymer Electrolyte Membrane Fuel Cell Model for Reformate Gas

Mamlouk

Sousa

Scott

2011

International Journal of Electrochemistry

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A one-dimensional model of a high temperature polymer electrolyte membrane fuel cell using polybenzimidazole (PBI) membranes is described. The model considers mass transport through a thin film electrolyte covering the catalyst particles as well as through the porous media. The incorporation of a thin film model describing reactant gas mass transport through electrolyte covering the electrocatalyst is shown to be an essential requirement for accurate simulation. The catalyst interface is represented using a macrohomogeneous model. The influence of carbon monoxide, carbon dioxide, and methane, which would be present in a reformate gas, is considered in terms of the effect on the anode polarisation/kinetics behaviour. The model simulates the influence of operating conditions, cell parameters, and fuel gas compositions on the cell voltage current density characteristics. The model gives good predictions of the effect of oxygen and air pressures on cell behaviour and correctly simulates the mass transport behaviour of the cell. The model with reformate gas shows that additional voltage losses associated with CO poisoning can lead to loss in voltage of tens of mV and thus reduction in power.

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Conductivity of PBI Membranes for High-Temperature Polymer Electrolyte Fuel Cells

Cited by 704 publications

References 40 publications

Sulfonated Polybenzimidazoles for High Temperature PEM Fuel Cells

Sulfonated Polybenzimidazoles for High Temperature PEM Fuel Cells

Raman study of the polybenzimidazole–phosphoric acid interactions in membranes for fuel cells

A High Temperature Polymer Electrolyte Membrane Fuel Cell Model for Reformate Gas

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