Sulphonated polyether ether ketone diaphragms used in commercial scale alkaline water electrolysis

Otero, Jesús; Sesé, J.; Michaus, Igor; Maria, Maria Santa; Guelbenzu, Eugenio; Irusta, Silvia; Carrilero, Isabel; Arruebo, Manuel

doi:10.1016/j.jpowsour.2013.09.062

Cited by 31 publications

(18 citation statements)

References 32 publications

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“…Asbestos has traditionally been used as diaphragm materials for the conventional alkaline technology but in contact with the electrolyte it shows stability problems at temperatures above 80°C [22] and it is gradually being phased out due to its severe toxicity [17]. A limited number of polymers, including poly(tetrafluoroethylene) (PTFE) [22][23][24], poly(phenylene sulfide) (PPS) [22,23], polypropylene [24,25] and different poly(arylene ether)s [23,26,27] are known to be relatively stable in hot aqueous solutions of potassium hydroxide and have thus been considered as asbestos replacements. Complete wetting of the diaphragm is required in order to develop the cross-sectional ion conducting pathways, but the strongly hydrophobic nature of the above mentioned polymers makes this difficult.…”

Section: Introductionmentioning

confidence: 99%

Porous poly(perfluorosulfonic acid) membranes for alkaline water electrolysis

Aili

Hansen

Andreasen

et al. 2015

Journal of Membrane Science

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Section: Introductionmentioning

confidence: 99%

Porous poly(perfluorosulfonic acid) membranes for alkaline water electrolysis

Aili

Hansen

Andreasen

et al. 2015

Journal of Membrane Science

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“…[11][12][13] Significant performance improvements of the conventional technology have been demonstrated using e.g. increased temperatures, 14 novel diaphragm materials, [15][16][17][18][19] active bubble removal 20,21 or advanced electrode designs. 22 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.…”

mentioning

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.

111

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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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“…More recently [33], it was found that a sulphonated poly-ether-ether-ketone (Figure 4.14) porous membrane could also be used as an alternative separator. Results obtained in water alkaline electrolysis using a 50 kW electrolyser stack were found very promising.…”

Section: Diaphragm/separatormentioning

confidence: 99%