Gas diffusion electrode, an electrolysis system, and a method for operating an electrolysis system
A gas diffusion electrode having at least two layers, of which a first layer has an electrically conductive fabric, which is embedded at least in part in a hydrophobically acting polymer matrix, and a second layer has an open porosity which has catalytically acting particles and has a thickness between 1 μm and 50 μm.
1 . A gas diffusion electrode comprising:
at least two layers of which a first layer comprises an electrically conductive woven fabric which is at least partially embedded in a hydrophobic polymer matrix and a second layer that is directly applied to the first layer, that comprises an open porosity in which catalytically active particles are present, that comprises a hydrophilic anion exchange monomer, and which has a thickness in the range from 1 μm to 50 μm;
wherein the catalytically active particles of the second layer have a diameter which is in the range from 0.05 μm to 1 μm;
wherein a first side of the electrically conductive woven fabric is configured to establish electrical communication with a contact web disposed adjacent the first layer;
wherein a second side of the electrically conductive woven fabric establishes electrically conductive contact points with the second layer;
wherein the electrically conductive woven fabric comprises a middle region that connects the first side to the second side, and wherein the middle region is electrically insulated in a manner effective to prevent direct electrical communication between the middle region and fluid in the first layer; and
wherein the middle region is coated by a coating comprising material that is different than a material of the hydrophobic polymer matrix.
2 . The gas diffusion electrode as claimed in claim 1 ,
wherein the electrically conductive woven fabric comprises a silver fiber.
3 . The gas diffusion electrode as claimed in claim 1 ,
wherein the hydrophobic polymer matrix has a contact angle with water of more than 90°.
4 . The gas diffusion electrode as claimed in claim 1 ,
wherein the first layer has a thickness in the range from 50 μm to 1000 μm.
5 . The gas diffusion electrode as claimed in claim 1 ,
wherein the hydrophobic polymer matrix has a porosity and wherein 95% of pores in the hydrophobic polymer matrix have a diameter which is in the range from 0.1 μm to 2 μm.
6 . The gas diffusion electrode as claimed in claim 1 ,
wherein the second layer comprises silver particles as the catalytically active particles.
7 . The gas diffusion electrode as claimed in claim 1 ,
wherein at least 95% of pores of the second layer have a diameter which is in the range from 0.1 μm to 5 μm.
8 . An electrolysis plant for electrolytic conversion of carbon dioxide, comprising:
a gas diffusion electrode as claimed in claim 1 .
9 . The electrolysis plant as claimed in claim 8 ,
wherein the electrolysis plant has a gas space and an electrolyte chamber, where the second layer of the gas diffusion electrode is arranged so as to face the electrolyte chamber.
10 . The electrolysis plant as claimed in claim 8 ,
further comprising the contact web.
11 . A method for operating an electrolysis plant, comprising:
introducing a carbon dioxide-containing a starting material into a gas space,
conveying the starting material to the gas diffusion electrode of claim 1 ,
wherein the starting material diffuses through a first layer of the gas diffusion electrode, after which the starting material arrives at an interface of the first layer with a second layer of the gas diffusion electrode and is reduced there, where the second layer is a porous layer which is impregnated with a liquid electrolyte.
12 . The gas diffusion electrode as claimed in claim 4 ,
wherein the first layer has a thickness in the range from 100 μm to 400 μm.
13 . The gas diffusion electrode as claimed in claim 5 ,
wherein 95% of the pores have a diameter which is in the range from 0.6 μm to 0.9 μm.
14 . The gas diffusion electrode as claimed in claim 1 ,
wherein the catalytically active particles of the second layer have a diameter which is in the range from 0.1 μm to 0.5 μm.
15 . The gas diffusion electrode as claimed in claim 7 ,
wherein at least 95% of the pores of the second layer have a diameter which is in the range from 0.1 μm to 1 μm.
16 . The gas diffusion electrode as claimed in claim 15 ,
wherein the gas diffusion electrode defines an interface between the first layer and the second layer; and
wherein in a region that is within the second layer and local to the interface, the pores of the second layer comprises a smaller diameter than the pores of the second layer that are further from the interface.
17 . The gas diffusion electrode as claimed in claim 16 ,
wherein in the region that is within the second layer and local to the interface, the diameter of the pores of the second layer is from 0.1 μm to 0.5 μm.
18 . The gas diffusion electrode as claimed in claim 1 ,
wherein the gas diffusion electrode defines an interface between the first layer and the second layer;
wherein the second layer comprises an additional binder; and
wherein the additional binder anchors the catalytically active particles on the hydrophobic polymer matrix of the first layer at the interface.
19 . The gas diffusion electrode as claimed in claim 1 ,
wherein both the first layer and the second layer comprise a respective porosity above 25%.