PROCESS AND MEMBRANE
A process for producing an ion-conducting membrane comprising a recombination catalyst-containing membrane layer. The membrane layer if fabricated from an ink comprising a stabilised dispersion of recombination catalyst nanoparticles. Also provided are ion-conducting membranes for electrochemical devices, such as fuel cells or water electrolysers, with a recombination catalyst-containing membrane layer comprising dispersed recombination catalyst nanoparticles, a nanoparticle stabilising agent, and an ion-conducting polymer.
1 . A process for producing an ion-conducting membrane comprising a recombination catalyst-containing membrane layer, the process comprising the steps of:
(i) providing a stabilised dispersion of recombination catalyst nanoparticles;
(ii) mixing the stabilised dispersion with an ion-conducting polymer to form an ink;
(iii) fabricating the membrane layer from the ink.
2 . A process according to claim 1 , wherein the recombination catalyst nanoparticles comprise platinum and/or palladium.
3 . A process according to claim 1 , wherein the stabilised dispersion of recombination catalyst nanoparticles comprises a nanoparticle stabilising agent with a higher hydrophobicity and/or a lower water uptake value than the ion-conducting polymer used in step (ii).
4 . A process according to claim 1 , wherein the stabilised dispersion comprises a polymeric nanoparticle stabilising agent.
5 . A process according to claim 1 , wherein the nanoparticle stabilising agent is polyvinylpyrrolidone (PVP).
6 . A process according to claim 1 , wherein step (iii) comprises depositing the ink onto a substate, such as a backing sheet, an ion-conducting polymer layer, or a catalyst layer on a backing sheet.
7 . A process according to claim 6 , wherein the substrate is a first ion-conducting polymer layer, and the process comprises step (iv) adding a second ion-conducting polymer layer such that the recombination catalyst-containing membrane layer is disposed between the first and the second ion-conducting polymer layers.
8 . A process according to claim 1 , further comprising the step of forming a catalyst layer on at least one face of the membrane to form a catalyst coated membrane.
9 . A process according to claim 8 , further comprising the step of applying a seal material to at least one face of the catalyst-coated membrane.
10 . (canceled)
11 . (canceled)
12 . (canceled)
13 . An ion-conducting membrane for an electrochemical device, such as a fuel cell or a water electrolyser, comprising a recombination catalyst-containing membrane layer, the membrane layer comprising dispersed recombination catalyst nanoparticles, a nanoparticle stabilising agent, and an ion-conducting polymer.
14 . An ion-conducting membrane according to claim 13 , wherein the nanoparticle stabilising agent has a higher hydrophobicity and/or a lower water uptake value than the ion-conducting polymer.
15 . An ion-conducting membrane according to claim 13 , wherein the recombination catalyst nanoparticles are in the form of clusters of discrete nanoparticles.
16 . An ion-conducting membrane according to claim 13 , wherein the nanoparticle stabilising agent is a polymer, such as polyvinylpyrrolidone.
17 . An ion-conducting membrane according to claim 13 , wherein the recombination catalyst nanoparticles are at least partially coated with the nanoparticle stabilising agent.
18 . An ion-conducting membrane according to claim 13 , wherein the average particle size of the nanoparticles is less than 50 nm.
19 . An ion-conducting membrane according to claim 13 , wherein the membrane has a thickness in the range of and including 30 to 90 mm.
20 . An ion-conducting membrane according to claim 13 , wherein the recombination catalyst-containing membrane layer has a thickness in the range of and including 5 to 30 mm.
21 . An ion-conducting membrane according to claim 13 , wherein the membrane is a single coherent polymer film comprising a plurality of ion-conducting polymer layers.
22 . An ion-conducting membrane according to claim 13 , comprising a first ion-conducting polymer layer and a second ion-conducting polymer layer, and wherein the recombination catalyst-containing membrane layer is disposed between the first and the second ion-conducting polymer layers.
23 . An ion-conducting membrane according to claim 22 , wherein the first ion-conducting polymer layer has a thickness in the range of and including 5 mm to 30 mm, preferably in the range of and including 5 mm to 20 mm.
24 . An ion-conducting membrane according to claim 22 , wherein the second ion-conducting polymer layer has a thickness in the range 10 mm to 90 mm, preferably in the range of and including 40 mm to 70 mm.
25 . A catalyst-coated membrane for an electrochemical device, such as a fuel cell or a water electrolyser, comprising an ion-conducting membrane according to claim 13 .
26 . (canceled)
27 . (canceled)