Exceptional durability enhancement of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200 °C

Aili, David; Zhang, Jin; Jakobsen, Mark Tonny Dalsgaard; Zhu, Haijin; Yang, Tianyu; Liu, Jian; Forsyth, Maria; Pan, Chao; Jensen, Jens Oluf; Cleemann, Lars; Jiang, San Ping; Li, Qingfeng

doi:10.1039/c6ta01562j

Cited by 98 publications

(62 citation statements)

References 42 publications

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“…For example, oxidation of the polymer may occur near the anode where oxygen is evolved. When doped with phosphoric acid, m-PBI appears stable for thousands of hours in fuel cells 54 but severely degrades within a few hours when operated in steam electrolysis mode. 55 To assess the effect of polarization on a slightly longer time-scale, the cells operating with 5, 15 and 30 wt% KOH were kept at 1.7 or 2.0 V for 2 days and the current density was recorded as functions of time.…”

Section: Resultsmentioning

confidence: 99%

Zero-Gap Alkaline Water Electrolysis Using Ion-Solvating Polymer Electrolyte Membranes at Reduced KOH Concentrations

Kraglund

Aili

Jankova

et al. 2016

J. Electrochem. Soc.

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118

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Membranes based on poly(2,2 -(m-phenylene)-5,5-bibenzimidazole) (m-PBI) can dissolve large amounts of aqueous KOH to give electrolyte systems with ion conductivity in a practically useful range. The conductivity of the membrane strongly depends on the concentration of the aqueous KOH phase, reaching about 10 −1 S cm −1 or higher in 15-25 wt% KOH. Herein, m-PBI membranes are systematically characterized with respect to performance and short-term stability as electrolyte in a zero-gap alkaline water electrolyzer at different KOH concentrations. Using plain uncatalyzed nickel foam electrodes, the cell based on m-PBI outperforms the cell based on the commercially available state-of-the-art diaphragm and reaches a current density of 1500 mA cm −2 at 2.4 V in 20 wt% KOH at 80 • C. The cell performance remained stable during two days of operation, though post analysis of the membrane using size exclusion chromatography and spectroscopy reveal evidence of oxidative degradation of the base polymer at KOH concentrations of 15 wt% and higher. Converting surplus electrical energy into hydrogen by water electrolysis represents an attractive approach to balance the electric grid when an increasing fraction of the power input originates from fluctuating renewable sources.1 Characterized by their robustness and durability, alkaline electrolyzers have been available for a long time on a commercial basis for large scale hydrogen and oxygen production through electrochemical water splitting.2,3 The alkaline environment allows for a cell construction completely free from noble metals, where the oxygen 4-6 and hydrogen 7-9 evolution reactions readily occur on nickel and other transition metal-based materials. The electrodes are separated by an aqueous solution of potassium hydroxide confined in a porous diaphragm to reduce the intermixing of the product gasses. Between the diaphragm and the electrode is an electrolyte-filled gap to facilitate gas removal. This cell design gives an interelectrode distance in the range of a few millimeters and therefore a relatively large internal resistance, 3,10 even though the specific conductivity of the aqueous potassium hydroxide electrolyte used is remarkably high. Replacing the diaphragm with an ion-conducting membrane represents a new direction in the development of advanced alkaline electrolyzers as recently discussed by Pletcher and Li. 23 It allows for a zero-gap design with an inter-electrode distance of less than 100 μm, in which the membrane is sandwiched in between two porous electrodes. One approach in this connection is to use alkaline ion exchange membranes (AEM) based on quaternary ammoniumfunctionalized polymers, [24][25][26] but improving the stability of the polymer backbone 27 as well as of the anion exchange moieties 28 are apparent challenges.An alternative approach is to use a membrane based on an aqueous electrolyte dissolved in a polymer matrix. The ion-solvating polymer electrolytes are often soluble in water, 29 but as first demonstrated by Xing and Savadogo, 30 poly(2,2...

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Section: Resultsmentioning

confidence: 99%

Zero-Gap Alkaline Water Electrolysis Using Ion-Solvating Polymer Electrolyte Membranes at Reduced KOH Concentrations

Kraglund

Aili

Jankova

et al. 2016

J. Electrochem. Soc.

Self Cite

118

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“…As shown early [25], in the PWA-meso-silica loading range of 0 -20 wt%, the effect of filler on the conductivity of the PA/PBI/PWA-meso-silica composite membranes is relatively small and with further increase of the filler loading, the proton conductivity of the composite membrane decreases. This may be due to the deteriated microstructure as shown in Fig.1.…”

Section: Phosphoric Acid Uptake and Mechanical Properties Of The Compmentioning

confidence: 96%

“…Nevertheless, the long-term stability of inorganic-organic composite membranes is seldom studied. Most recently, we developed high temperature PEMs based on phosphotungstic acid impregnated mesoporous silica (PWAmeso-silica) and PA/PBI inorganic-organic composites [25]. In this study, we have carried out detailed studies of the microstructural changes, proton conductivity and performance stability of PA/PBI/PWA-meso-silica composite membrane fuel cells.…”

Section: Introductionmentioning

confidence: 99%

In Situ Formed Phosphoric Acid/Phosphosilicate Nanoclusters in the Exceptional Enhancement of Durability of Polybenzimidazole Membrane Fuel Cells at Elevated High Temperatures

Zhang

Aili

Bradley

et al. 2017

J. Electrochem. Soc.

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“…Maximizing the phosphoric acid content of the membrane is thus the most straightforward approach to reducing the internal resistance . However, the phosphoric acid tend to redistribute , or leach out during operation, which represents a predominating degradation mode of the fuel cell performance. This is particularly severe at high current loads, at high gas flow rates and at temperature in the higher end of the operating temperature window .…”

Section: Introductionmentioning

confidence: 99%

“…This is particularly severe at high current loads, at high gas flow rates and at temperature in the higher end of the operating temperature window . Introduction of an inorganic phase, such as titanyl sulfate , titania , or mesoporous silica , , in the membrane matrix may stabilize the performance and extend the lifetime. Ideally, replacing the phosphoric acid with a solid‐state proton conductor would be a rational strategy to mitigate this degradation mode.…”

Section: Introductionmentioning

confidence: 99%

Fuel Cell Electrolytes of Polybenzimidazole Membranes Cross‐linked with Bis(chloromethyl) Arenes

et al. 2018

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Cross‐linking of phosphoric acid doped polybenzimidazole membranes as fuel cell electrolytes represents an attractive approach to improving the mechanical robustness at a high acid loading. Numerous cross‐linking concepts have been reported in the literature, but a deeper understanding of how the cross‐linking chemistry affects the physicochemical properties of the membrane and its fuel cell performance and durability remains to be assessed. In this work, a series of cross‐linked membranes are prepared using cross‐linking agents of different regio‐chemistry and steric nature. It is shown, that the nature of the cross‐linking agent has a large impact on the effective degree of cross‐linking, which in turn determines the acid doping characteristics and ultimately the fuel cell performance and acid retention during long‐term operation.

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Exceptional durability enhancement of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200 °C

Abstract: Q. (2016). Exceptional durability enhancement of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200°C.

Cited by 98 publications

References 42 publications

Zero-Gap Alkaline Water Electrolysis Using Ion-Solvating Polymer Electrolyte Membranes at Reduced KOH Concentrations

Zero-Gap Alkaline Water Electrolysis Using Ion-Solvating Polymer Electrolyte Membranes at Reduced KOH Concentrations

In Situ Formed Phosphoric Acid/Phosphosilicate Nanoclusters in the Exceptional Enhancement of Durability of Polybenzimidazole Membrane Fuel Cells at Elevated High Temperatures

Fuel Cell Electrolytes of Polybenzimidazole Membranes Cross‐linked with Bis(chloromethyl) Arenes

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