Methanol permeability and proton conductivity of polybenzimidazole and sulfonated polybenzimidazole

Pu, Hongting; Liu, Qizhi

doi:10.1002/pi.1577

Cited by 41 publications

(25 citation statements)

References 25 publications

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“…This is a simple method to determine the methanol permeability via diffusion, which would be the dominating mechanism in case of a zero electricosmotic drag coefficient for PBI membranes. As listed in Table 2, the results show a degree of scatter, even from the same research group [114,211]. It seems that undoped PBI membranes exhibit a methanol crossover rate of about 10 −10 mol cm −1 s −1 at room temperature, as compared to 10 −8 mol cm −1 s −1 for Nafion 117 membranes.…”

Section: Electro-osmotic Water Drag and Methanol Crossovermentioning

confidence: 85%

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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Section: Electro-osmotic Water Drag and Methanol Crossovermentioning

confidence: 85%

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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“…The sulfonated PBIs (s-PBIs) have typically been proposed as Nafion alternatives and most characterization has been done with water as an electrolyte, [29][30][31]34,39,40,[43][44][45][46][47][48] but a small amount of investigation into PA-doped s-PBIs has been performed. 30,33,38,41,44,46,47 Structures that have been studied include grafting of aryl-or alkyl-sulfonates to the imidazole moiety, postsulfonation onto the biphenyl or diacid phenyl ring, copolymers of sulfonated PBI-type polymers with other sulfonated polymers, postsulfonation of PBI-type polymers with ether linkages incorporated into the backbone, and PBIs made with a sulfonated tetraamine.…”

Section: Introductionmentioning

confidence: 99%

“…30,33,38,41,44,46,47 Structures that have been studied include grafting of aryl-or alkyl-sulfonates to the imidazole moiety, postsulfonation onto the biphenyl or diacid phenyl ring, copolymers of sulfonated PBI-type polymers with other sulfonated polymers, postsulfonation of PBI-type polymers with ether linkages incorporated into the backbone, and PBIs made with a sulfonated tetraamine. Initial results show these polymers to be promising low or high temperature membranes, depending on the dopant.…”

Section: Introductionmentioning

confidence: 99%

“…13,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] Three common approaches are typically employed for functionalizing PBI: (1) direct sulfonation of the backbone, 29,47,49 (2)chemical grafting of functionalized monomers, 31,35 or (3) polycondensation of a sulfonated aromatic diacid with an aromatic tetraamine. 30,50 The last method provides advantages over the first two, such as limitation of side reactions and control over the degree of sulfonation.…”

Section: Introductionmentioning

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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“…Several authors have determined methanol permeability for PBI [12,192,197,280,413], methyl and ethyl-PBI [197], and fluorinated PBI [198,414], for different acid doping degree. The reported permeability coefficients are summarized in Fig.…”

Section: Acid Doped Pbi Membranesmentioning

confidence: 99%

Membranes for Direct Alcohol Fuel Cells

Corti

2013

Direct Alcohol Fuel Cells

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This chapter is devoted to summarize and discuss the main properties of ionomeric membranes used in direct alcohol PEM fuel cells. Although Nafion is the proton exchange membrane commonly used in methanol and other direct alcohol fuel cells, other proton and alkaline membranes are being investigated in order to improve the efficiency of DAFC. The goals in the development of this critical component of DAFC are: low cost, long durability, low alcohol permeability and high electrical conductivity. The last two properties can be combined in a single parameter, the membrane selectivity that accounts for the ratio between the proton and alcohol transport through the membrane. This parameter can be compared to that measured for Nafion to define a relative selectivity, which is a primary parameter to evaluate the potentiality of a ionomer material to be used in alcohol feed fuel cells.The vast catalogue of polymeric materials reviewed here included Nafion composite with inorganic and organic fillers, and non-fluorinated proton conducting membranes such as sulfonated polyimides, poly(arylene ether)s, polysulfones, poly (vinyl alcohol), polystyrenes, and acid-doped polybenzimidazoles. Anionexchange membranes are also discussed because of the facile electro-oxidation of alcohols in alkaline media and because of the minimization of alcohol crossover in alkaline direct alcohol fuel cells.The performance of different types of membranes in direct alcohol fuel cells, mainly methanol, are summarized and discussed in order to identify the most promissory ones. The lack of correlation between the relative selectivity and fuel cell performance of the membranes indicates that the architecture of the three

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Methanol permeability and proton conductivity of polybenzimidazole and sulfonated polybenzimidazole

Cited by 41 publications

References 25 publications

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

Sulfonated Polybenzimidazoles for High Temperature PEM Fuel Cells

Membranes for Direct Alcohol Fuel Cells

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