Study on Separator for Alkaline Water Electrolysis

Manabe, Akiyoshi; Domon, Hiroki; Kosaka, Junko; Hashimoto, Terumi; Okajima, Takaharu; Ohsaka, Takeo

doi:10.1149/2.0191611jes

Cited by 14 publications

(6 citation statements)

References 19 publications

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“…δ sep [15] The product of the effective diffusion and solubility coefficient D eff H 2 S H 2 is frequently provided in form of the permeability coefficient K H 2 , which is a classical material property for separating units.…”

Section: Crossover Mechanismsmentioning

confidence: 99%

“…Furthermore, strategies are provided, which may be used for an improved anodic gas purity. 7,15,16 The present contribution firstly provides a summary on the occurring crossover mechanisms in PEM and alkaline water electrolysis. Subsequently, experimental data of the influence of current density, system pressure and various process management possibilities on the anodic hydrogen content is shown for both electrolysis technologies.…”

mentioning

confidence: 99%

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Hydrogen Crossover in PEM and Alkaline Water Electrolysis: Mechanisms, Direct Comparison and Mitigation Strategies

Trinke

Haug

Brauns

et al. 2018

J. Electrochem. Soc.

179

126

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This study provides a direct comparison of hydrogen crossover in PEM (Nafion 117) and alkaline water electrolysis (Zirfon) at a temperature of 60 • C applying state-of-the-art separating unit materials. To this end, occurring crossover mechanisms are described first, before experimental data of the anodic hydrogen content are shown in dependence of current density, system pressure and process management strategy. The results suggest that permeation in PEM electrolyzers is mainly governed by diffusion due to a supersaturated concentration of dissolved hydrogen within the catalyst layer, showing a share of 98% of the total permeation flux at 1 A cm −2 and atmospheric pressure. Permeation in alkaline electrolyzers also exhibits a significant influence of supersaturation, but the overall crossover is mainly influenced by mixing the electrolyte cycles, which makes up a share of 90% at 0.7 A cm −2 and 1 bar. Generally it becomes evident that hydrogen permeation across the separating unit is more than one order of magnitude smaller in alkaline electrolysis, which is mainly a consequence of the significantly lower hydrogen solubility in concentrated KOH electrolyte. Finally, this study concludes with an assessment of the impact of separating unit thickness and provides mitigation strategies to reduce hydrogen crossover.

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Section: Crossover Mechanismsmentioning

confidence: 99%

mentioning

confidence: 99%

Hydrogen Crossover in PEM and Alkaline Water Electrolysis: Mechanisms, Direct Comparison and Mitigation Strategies

Trinke

Haug

Brauns

et al. 2018

J. Electrochem. Soc.

179

126

View full text Add to dashboard Cite

show abstract

“…17 The traditional AWE can produce H 2 and O 2 simultaneously, and the anodic and cathodic reactions need to be separated by an effective separator, which allows the movement of ions but rejects the gas crossover. 18 Asbestos, 19 fabric of polyphenylene sulfide (PPS), 20 and composite materials are widely used in commercial AWEs. In the traditional separator based reactors, the electrolytes are the same in both the anodic and cathodic cells (Figure 2a).…”

Section: Reactors For Coupled Systems Of Her and Electro-oxidationmentioning

confidence: 99%

Minireview of Coupled Electrochemical Hydrogen Production and Organic-Oxidation for Low Energy Consumption

Chen,

Fu,

Peng

et al. 2023

Energy Fuels

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Hydrogen production from electrochemical water splitting has attracted great attention due to its supply to green energy. However, commercial alkaline water electrolysis is energy intensive due to inert and large overpotentials of anodic oxygen evolution reaction (OER). Electro-oxidation of organics is an attractive alternative to the OER. With electro-oxidation of special organic substrates on an active anode, decreased cell voltage of H 2 evolution can be achieved along with the production of valueadded products. In this review, we summarize the latest progress on coupled H 2 production with organic electro-oxidation systems. Different organic compounds containing oxygen (alcoholic hydroxyl, aldehydes, ketone), nitrogen, sulfides, and olefin/alkane groups have been selectively oxidized into high value-added products on the anodes, thereby promoting H 2 evolution on the cathodes. Some complicated coupling reactions, such as the formation of C−C and C−N, are also introduced in the coupling systems. In addition, the challenges and prospects for the future development of this research field are highlighted.

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“…Asbestos is no longer used as a separator due to its carcinogenic properties and its instability at high temperature . A PPS fabric or felt shows a low bubble point pressure below 0.02 bar, which is not suitable for application in a pressurized AWE …”

Section: Introductionmentioning

confidence: 99%

“…13 A PPS fabric or felt shows a low bubble point pressure below 0.02 bar, 14 which is not suitable for application in a pressurized AWE. 15 Composite materials composed of hydrophilic nanoparticles and polymers with good film-forming properties are mainly used for high bubble point pressure and stability. The commercial composite separator, Zirfon PERL, which is composed of 85 wt.% ZrO 2 nanoparticles and 15 wt.% polysulfone (PSU), is very stable in 30 wt.% KOH solution at approximately 80 C. The high quantity of ZrO 2 nanoparticles in Zirfon PERL separator contributes to the low area resistance (<0.3 Ω cm 2 ) and high bubble point pressure (2 ± 1 bar) due to increased wettability.…”

mentioning

confidence: 99%

The synthesis of a Zirfon‐type porous separator with reduced gas crossover for alkaline electrolyzer

et al. 2019

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Summary The rapid expansion of renewable energy sources presents a great challenge to balance the electric grid due to their intermittent and volatile nature. The surplus energy generation cannot be used or sold so that it is curtailed in order to maintain the grid balance. The excess power can be converted into a gaseous energy carrier, hydrogen via power‐to‐gas technology. Alkaline water electrolysis can be operated in a dynamic mode using renewable energy sources on a large scale. However, the risk of gas crossover across a porous separator rapidly increases when the electrolyzer operates at a low partial load or at high pressure, leading to efficiency loss and a safety issue. The commercial porous separator Zirfon PERL, which is composed of 85 wt.% zirconia nanoparticles and 15 wt.% polysulfone, exhibits a satisfactory bubble point pressure performance of approximately 2.5 bar and ionic resistance of 0.3 Ω cm2. However, the Zirfon PERL separator exhibits a high hydrogen permeability value of 20 × 10−12 mol cm−1 bar−1 sec−1 due to its large average pore size of 130 nm, resulting in a limited dynamic range of the electrolyzer. Therefore, it is necessary to develop a porous separator with reduced gas crossover. In this study, we synthesize a porous ZrO2/polysulfone composite separator by varying the amount of ZrO2 (75‐85 wt.%) via the film‐casting method. The 75 wt.% ZrO2/25 wt.% polysulfone composite separator, which contains a low amount of ZrO2, shows a high bubble point pressure of 3.8 bar, a low ionic resistance of 0.3 Ω cm2, and are reduced hydrogen permeability of 4.2 × 10−12 mol cm−1 bar−1 sec−1 compared with that of Zirfon PERL separator. The enhanced performance of this separator is attributed to the reduced average pore size of around 70 nm and high surface wettability with a contact angle of 75°. This result will help alkaline electrolyzer systems be operated as more controllable loads.

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Study on Separator for Alkaline Water Electrolysis

Cited by 14 publications

References 19 publications

Hydrogen Crossover in PEM and Alkaline Water Electrolysis: Mechanisms, Direct Comparison and Mitigation Strategies

Hydrogen Crossover in PEM and Alkaline Water Electrolysis: Mechanisms, Direct Comparison and Mitigation Strategies

Minireview of Coupled Electrochemical Hydrogen Production and Organic-Oxidation for Low Energy Consumption

The synthesis of a Zirfon‐type porous separator with reduced gas crossover for alkaline electrolyzer

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