Real‐Time Mass Spectrometric Study of the Methanol Crossover in a Direct Methanol Fuel Cell

Wang, J.‐T.; Wasmus, S.; Savinell, Robert F.

doi:10.1149/1.1836622

Cited by 234 publications

(103 citation statements)

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“…For PBI membranes, the electro-osmotic drag coefficient of methanol was found to be essentially zero [207]. Similar results of the methanol crossover rate were obtained by a methanol sorption/permeation method [21] and a realtime spectrometric analysis of the cathode exhaust stream of a fuel cell operating with a current [210], indicating little contribution of the electro-osmotic drag mechanism. For PBI membranes doped with 5 mol H 3 PO 4 per repeat unit at 150 • C and 50/50 water/methanol vapour, the methanol crossover was found to be corresponding to less than 10 mA cm −2 for a 100 m thick membrane [21,210], equivalent to a methanol crossover rate of about 10 −10 mol cm −1 s −1 bar −1 .…”

Section: Electro-osmotic Water Drag and Methanol Crossoversupporting

confidence: 74%

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

Jensen

Savinell

et al. 2009

Progress in Polymer Science

1,242

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 Crossoversupporting

confidence: 74%

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

Jensen

Savinell

et al. 2009

Progress in Polymer Science

1,242

852

View full text Add to dashboard Cite

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“…Several non-fluorinated polymeric materials have been investigated as replacements for Nafion due to low cost and ease of synthesis [5][6][7][8][9][10][11][12], but they are generally based on free sulfonic acid groups and experience severe dimensional swelling in DMFC at high degree of sulfonation, resulting in mechanical instability problems [1,12,13]. Cross-linked ionomers have been pursued to overcome this problem, but they usually lead to a sacrifice in fuel cell performance and microphase-separation is easy to occur in such blends due to different, incompatible acidic (aromatic) and basic (polybenzimidazole) polymer structures [14,15].…”

Section: Introductionmentioning

confidence: 99%

Acid–base blend membranes based on 2-amino-benzimidazole and sulfonated poly(ether ether ketone) for direct methanol fuel cells

Manthiram

Guiver

2007

Electrochemistry Communications

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Direct methanol fuel cells (DMFC) are attractive for portable and automobile power needs, but their commercialization is hampered by high methanol permeability and the high cost of the currently used Nafion membrane. We report here a novel, low-cost blend membrane consisting of polysulfone-2-amide-benzimidazole (a basic polymer) and sulfonated poly(ether ether ketone) (an acidic polymer), which facilitates proton conduction through acid-base interactions while preserving excellent chemical and mechanical stabilities. The blend membrane exhibits performance in DMFC much higher than that of Nafion 115 and similar to that of Nafion 112, but with a remarkably superior long-term performance than Nafion 112 due to significantly reduced methanol crossover, enhancing the commercialization prospects of DMFC.

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“…It was expected an increase of cathode losses due to methanol crossover and consequent oxidation in the presence of oxygen and platinum [5,19,21]. Furthermore, at 180 ºC, it is expected an increase in cathode tolerance to methanol, despite the possible increase in the methanol crossover [6].…”

Section: Eismentioning

confidence: 99%

“…A high temperature DMFC was first studied in the 1990's using phosphoric acid doped PBI as electrolytes [3][4][5]. The assembled DMFC reached a maximum of 0.1 W·cm -2 , at 200 °C [4].…”

Section: Introductionmentioning

confidence: 99%

The influence of impurities in high temperature polymer electrolyte membrane fuel cells performance

Boaventura

Alves

Ribeirinha

et al. 2016

International Journal of Hydrogen Energy

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This work investigates the influence of carbon dioxide and non-reacted methanol, present in the reformate stream obtained via methanol steam reforming, in the performance of high temperature polymer electrolyte membrane fuel cells (HT-PEMFC), operating between 160 °C and 180 °C.The HT-PEMFC anode was fed with pure hydrogen, hydrogen balanced with carbon dioxide (75 % / 25 % vol.) and synthetic reformate mixture, considering also vaporized methanol solution in the reformate content (up to 10 % vol.). The synthetic reformate was feed during cycles of 420 min. The fuel cell was characterized based on the polarization curve and electrochemical impedance spectroscopy (EIS) analysis. Additionally, acid-base titrations were performed to access the phosphoric acid content in different sections of the MEAs as well as scanning electron microscopy (SEM).A low impact in the fuel cell performance was observed when three cycles of synthetic reformate containing methanol solution were performed. When the number of cycles was increased, the performance of HT-PEMFC decreases and irreversible degradation of performance was observed. The cycles with synthetic reformate increased the ohmic resistance and high frequency resistance associated with anodic processes, but decreased the intermediate frequency resistance associated with cathodic processes. Additionally, by increasing the number of cycles, the phosphoric acid content of Celtec ® MEAs and the thickness of the membrane decreased. Keywords:Polymer electrolyte membrane fuel cell Polybenzimidazole Reformate gas Methanol Impurities effectElectrochemical impedance spectroscopy

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Real‐Time Mass Spectrometric Study of the Methanol Crossover in a Direct Methanol Fuel Cell

Cited by 234 publications

References 1 publication

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

Acid–base blend membranes based on 2-amino-benzimidazole and sulfonated poly(ether ether ketone) for direct methanol fuel cells

The influence of impurities in high temperature polymer electrolyte membrane fuel cells performance

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