MEMBRANE
An electrolyte membrane comprising a recombination catalyst layer. The membrane has a thickness of less than or equal to 100 μm and is a single coherent polymer film comprising a plurality of ion conducting polymer layers. The recombination catalyst layer comprises particles of an unsupported recombination catalyst dispersed in an ion conducting polymer and the layer has a thickness in the range of and including 5 to 30 μm. Catalyst coated membranes (CCMs) incorporating the electrolyte membranes are also provided, together with methods of manufacturing the electrolyte membranes.
1 . An electrolyte membrane comprising a recombination catalyst layer, the membrane having a thickness of less than or equal to 100 mm, and wherein the recombination catalyst layer satisfies the following requirements:
(i) the layer comprises particles of an unsupported recombination catalyst dispersed in an ion conducting polymer;
(ii) the layer has a thickness in the range of and including 5 to 30 mm;
and the electrolyte membrane is a single coherent polymer film comprising a plurality of ion conducting polymer layers.
2 . The electrolyte membrane according to claim 1 , wherein the recombination catalyst is selected from one or more of platinum, palladium, and alloys or mixed oxides thereof.
3 . The electrolyte membrane according to claim 1 , wherein the particles of unsupported recombination catalyst have a particle size distribution such that the d90 is less than or equal to 3.0 mm.
4 . The electrolyte membrane according to claim 1 , wherein the particles of unsupported recombination catalyst have an average particle size greater than 0.1 mm.
5 . The electrolyte membrane according to claim 1 , wherein the membrane has a thickness in the range of and including 5 to 100 mm.
6 . The electrolyte membrane according to claim 1 , wherein the membrane comprises a reinforcement polymer, such as expanded polytetrafluoroethylene (ePTFE) or polybenzimidazole (PBI).
7 . The electrolyte membrane according to claim 1 comprising a first ion conducting polymer layer and a second ion conducting polymer layer, and wherein the recombination catalyst layer is disposed between the first and the second ion conducting polymer layers.
8 . The electrolyte membrane according to claim 7 , wherein the membrane comprises a reinforcement polymer and wherein the reinforcement polymer is present in the first ion conducting polymer layer and/or the second ion conducting polymer layer.
9 . The electrolyte membrane according to claim 7 , wherein the first ion conducting polymer layer has a thickness in the range of and including 5 mm to 30 mm.
10 . The electrolyte membrane according to claim 7 , wherein the second ion conducting polymer layer has a thickness in the range 10 mm to 90 mm.
11 . The electrolyte membrane according to claim 7 , wherein the second ion conducting layer contains two regions of reinforcement polymer.
12 . The electrolyte membrane according to claim 1 , wherein the recombination catalyst layer has a thickness in the range of and including 5 to 15 mm.
13 . A catalyst coated membrane for an electrochemical device, such as a water electrolyser, comprising the electrolyte membrane according to claim 1 .
14 . The catalyst coated membrane according to claim 13 , wherein the electrolyte membrane comprises a first ion conducting polymer layer and a second ion conducting polymer layer with the recombination catalyst layer disposed between the first and second ion conducting polymer layers, and wherein an anode catalyst layer is disposed on a first face of the first ion conducting polymer layer, and the second face of the first ion conducting polymer layer faces in the direction of the recombination catalyst layer.
15 . The catalyst coated membrane in accordance with claim 14 , wherein the thickness of the first ion conducting layer is less than the thickness of the second ion conducting layer.
16 . The catalyst coated membrane according to claim 13 , wherein the electrolyte membrane comprises a first ion conducting polymer layer and a second ion conducting polymer layer with the recombination catalyst layer disposed between the first and second ion conducting polymer layers, and wherein a cathode catalyst layer is disposed on a first face of the second ion conducting polymer layer, and the second face of the second ion conducting polymer layer faces in the direction of the recombination catalyst layer.
17 . The catalyst coated membrane according to claim 14 , wherein the first ion conducting polymer layer has a thickness in the range of and including 5 mm to 30 mm.
18 . The catalyst coated membrane according to claim 14 , wherein the second ion conducting polymer layer has a thickness in the range of and including 10 mm to 90 mm.
19 . A water electrolyser comprising the membrane according to claim 1 .
20 - 24 . (canceled)