OXYGEN-CONSUMING ELECTRODE AND PROCESS FOR THE PRODUCTION THEREOF
The present invention relates to an oxygen-consuming electrode comprising at least one support element in the form of a sheet-like structure and a coating comprising a gas diffusion layer and a catalytically active component, wherein the oxygen-consuming electrode is additionally coated with a fluoropolymer which is soluble in solvents.
1 . An oxygen-consuming electrode comprising at least one support element in the form of a sheet-like structure and a coating comprising a gas diffusion layer and a catalytically active component, wherein the oxygen-consuming electrode is additionally coated with a fluoropolymer which is soluble in solvents.
2 . The oxygen-consuming electrode according to claim 1 , wherein the oxygen-consuming electrode is coated on the side facing the gas with the fluoropolymer which is soluble in solvents.
3 . The oxygen-consuming electrode according to claim 1 , wherein the fluoropolymer which is soluble in solvents comprises a copolymer which comprises perhalo-2,2-alkyl-1,3-dioxoles and at least one perfluorinated alkene compound as a monomer.
4 . The oxygen-consuming electrode according to claim 1 , wherein the fluoropolymer which is soluble in solvents comprises a copolymer which comprises perfluoro-2,2-alkyl-1,3-dioxoles and at least one fluorinated olefin or fluorinated vinyl ether as a monomer.
5 . The oxygen-consuming electrode according to claim 1 , wherein the fluoropolymer which is soluble in solvents comprises a copolymer which comprises perfluoro-2-methylene-4-methyl-1,3-dioxolane (PMD) or 2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole (PDD) and at least one further,
6 . The oxygen-consuming electrode according to claim 1 , wherein the fluoropolymer which is soluble in solvents comprises a copolymer which comprises 2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole (PDD) and at least one further monomer selected from the group consisting of tetrafluoroethylene, hexafluoropropylene and perfluoro(butenyl vinyl ether).
7 . The oxygen-consuming electrode according to claim 1 , wherein the solvent comprises a perfluorinated hydrocarbon compound or a perfluorinated derivatized hydrocarbon compound or a mixture of these compounds.
8 . The oxygen-consuming electrode according to claim 1 , wherein the solvent comprises perfluoro(2-butyltetrahydrofuran).
9 . The oxygen-consuming electrode according claim 1 , wherein the electrode is coated with from 1 to 100 g of fluoropolymer per square meter of electrode area.
10 . The oxygen-consuming electrode according to claim 1 , wherein the layer thickness of the fluoropolymer layer is from 0.01-100 μm.
11 . The oxygen-consuming electrode according to claim 1 , wherein the catalytically active component comprises silver, silver (I) oxide or silver (II) oxide or mixtures of silver and silver oxide.
12 . The oxygen-consuming electrode according to claim 1 , wherein the oxygen consuming electrode comprises a mixture comprising from 70 to 95% by weight of silver oxide as the catalytically active component, from 0-15% by weight of silver metal powder and 3-15% by weight of an insoluble fluorinated polymer.
13 . The oxygen-consuming electrode according to claim 1 , wherein the gas diffusion layer comprises an insoluble fluorinated polymer.
14 . The oxygen-consuming electrode according to claim 1 , wherein the support element has a flexible textile structure.
15 . The oxygen-consuming electrode according to claim 1 , wherein the support element has a flexible textile structure that is made of metal threads.
16 . A process for producing the oxygen-consuming cathode according to claim 1 , which comprises applying or spraying a solution of a fluoropolymer onto an oxygen-consuming electrode comprising at least one support element in the form of a sheet-like structure and a coating having a gas diffusion layer and a catalytically active component and subsequently removing the solvent by evaporation.
17 . An oxygen-consuming cathode in an electrolysis apparatus or an electrode in an alkaline fuel cell or an electrode in a metal/air battery comprising the oxygen consuming electrode according to claim 1 .
18 . An electrolysis apparatus, comprising the oxygen-consuming electrode according to claim 1 as an oxygen-consuming cathode.
19 . A process for repairing, sealing or improving damaged or used oxygen-consuming electrodes comprising coating the oxygen-consuming electrode with a compound comprising fluoropolymers which are soluble in solvents.
20 . The process according to claim 19 , wherein the fluoropolymer which are soluble in solvents comprises a copolymer made up of at least a compound selected from the group consisting of perhalo-2,2-alkyl-1,3-dioxoles, and at least one further monomer selected from the group consisting of perfluorinated alkene compounds.