Direct coating of anion exchange membranes with catalytically active material

Patent metadata

Field	Value
Publication number	US-2025332550-A1
Application number	US-202519169391-A
Country	US
Kind code	A1
Filing date	Apr 3, 2025
Priority date	Apr 29, 2024
Publication date	Oct 30, 2025
Grant date	—

Abstract

The invention relates to the coating of anion exchange membranes (AEM) with catalytically active substances. The CCM thus obtained are used in electrochemical cells, especially for alkaline water electrolysis. It was an object of the invention to specify a process for producing a CCM by direct coating which maintains the necessary planarity of the AEM and ideally avoids the use of lost films and eschews CMR substances. Swelling shall also be minimized. The process shall also be performable with fluorine-free ionomers. The invention is based on the finding that the addition of certain organic substances has the result that the AEM swells only to a small extent, if at all (antiswelling agent). It has surprisingly been found that substances suitable as antiswelling agents are identifiable by their solubility behaviour, more particularly by their Hansen parameters.

First claim

1 . Process for producing a coated anion exchange membrane comprising the following non-chronological steps
a) providing a viscous composition containing at least the following components:
i) an electrocatalyst;
ii) a solvent;
iii) an anion-conducting polymer;
b) providing an anion exchange membrane containing at least one membrane material; c) applying the viscous composition to the anion exchange membrane; d) drying the viscous composition applied to the anion exchange membrane; e) obtaining a coated anion exchange membrane which comprises at least on one side a layer comprising the electrocatalyst and the anion-conducting polymer, wherein the electrocatalyst is joined to the membrane material via the anion-conducting polymer; wherein the anion-conducting polymer, the membrane material and the solvent are selected to be matched to one another such that the anion-conducting polymer and the membrane material are each soluble in the solvent; characterized in that the viscous composition additionally contains the following component:
iv) an organic substance distinct from the solvent;
wherein the solubility parameters δD, δP and δH of the organic substance determined according to Hansen are in the following ranges:

15
⁢

⁢

MPa
0.5

<

δ
⁢

⁢
D

<

35
⁢

⁢

MPa
0.5

6
⁢

⁢

MPa
0.5

<

δ
⁢

⁢
P

<

15
⁢

⁢

MPa
0.5

2.5
⁢

⁢

MPa
0.5

<

δ
⁢

⁢
H

<

7.1
⁢

⁢

MPa
0.5

2 . Process according to claim 1 , wherein the organic substance is selected from the group consisting of the following substances: (1S,5R)-6,8-dioxabicyclo[3.2.1]octan-4-one, cyclopentanone, cyclohexanone, cycloheptanone, benzonitrile, acetone, butanone, acetophenone.

3 . Process according to claim 1 , characterized in that the solvent is selected from the group consisting of the following substances: dimethyl sulfoxide, ethanol, methanol, 1-propanol, 2-propanol, acetonitrile.

4 . Process according to claim 3 , characterized in that the solvent is a solvent mixture containing two or more substances selected from the recited group.

5 . Process according to claim 1 , characterized in that the anion-conducting polymer is completely dissolved in the solvent or the solvent mixture.

6 . Process according to claim 1 , characterized in that the electrocatalyst is in particulate form and contains at least one element selected from the group consisting of the following elements: iridium (Ir), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), ruthenium (Ru), copper (Cu), molybdenum (Mo), zinc (Zn), lead (Pb), manganese (Mn), tungsten (W), platinum (Pt), sulfur(S), tin (Sn), gold (Au), silver (Ag), palladium (Pd), rhenium (Re), rhodium (Rh), cerium (Ce), wherein the element is present in its pure form or as oxide or as hydroxide or as oxide hydroxide or as phosphide.

7 . (canceled)

8 . Process according to claim 1 , characterized in that the viscous composition additionally comprises the following component:
v) a dispersing medium; wherein the dispersing medium is identical neither to the solvent or the solvent mixture nor to the organic substance.

9 . Process according to claim 8 , characterized in that the dispersing medium is water.

10 . Process according to any of claim 1 , characterized in that the weight fractions of the components, in each case based on the total weight of the viscous composition, are in the following ranges with the proviso that the sum of the weight fractions of all components listed here does not exceed 100% by weight:

Minimum
Maximum

content (%
content (%

Component
by wt.)
by wt.)

Electrocatalyst
1
30

solvent
10
40

organic substance
45
90

Anion-conducting polymer
0.1
10

Dispersing medium
0
20

11 . Process according to claim 1 additionally containing at least one additive, wherein the additive is selected from the group consisting of the following additives: rheology aid, conductivity additive.

12 . (canceled)

13 . Process according to claim 1 , wherein the viscous composition has a dynamic viscosity η, for which a characteristic value is determ

Assignees

• Evonik Operations Gmbh

Inventors

• Watzele Sebastian
• Merkulov Sonja
• Wild Andreas

Classifications

• H01M4/926

  on carbon or graphite · CPC title

• H01M4/88

  Processes of manufacture · CPC title

• H01M8/083 Primary

  Alkaline fuel cells · CPC title

• Y02E60/36

  Hydrogen production from non-carbon containing sources, e.g. by water electrolysis · CPC title

• B01J23/70

  of the iron group metals or copper · CPC title