Method for producing a membrane electrode including forming the membrane in situ
A hydrophilic cross-linked polymer obtainable by copolymerisation of hydrophobic and hydrophilic monomers that give a cross-linked hydrophilic polymer on polymerisation; a monomer including a strongly ionic group; and water is useful as the membrane in an assembly that can be used in an electrolyter or fuel cell. More generally, a membrane electrode assembly comprises electrodes and an ion-exchange membrane which comprises a hydrophilic polymer including a strongly ionic group. A method for producing a membrane electrode assembly comprising electrodes and an ion-exchange membrane, comprises introducing between the electrodes a material or materials from which the membrane can be formed, and forming the membrane in situ.
1. A method for producing a membrane electrode assembly comprising electrodes and an ion-exchange membrane, wherein said method comprises:
introducing in a space between the electrodes a material or materials from which the ion exchange membrane is formed, wherein the material or materials comprises monomers having ionic sites; and
forming the ion exchange membrane in situ in the space between the electrodes by free-radical polymerisation, thermal polymerisation, or polymerisation by irradiation,
wherein the ion exchange membrane comprises a matrix of a polymer,
wherein the matrix comprises ionic sites directly fixed within it by chemical bonding, and
wherein the fixed ionic sites are introduced from the monomers.
2. The method, according to claim 1 , wherein the forming of the ion exchange membrane comprises in situ polymerisation of the monomers or a pre-polymer comprising the monomers.
3. The method, according to claim 2 , wherein the polymer is a hydrophilic polymer including an ionic group.
4. The method, according to claim 1 , wherein the membrane electrode assembly is in the form of an electrochemical cell.
5. The method, according to claim 1 , wherein forming the ion exchange membrane in situ comprises subjecting the material or materials from which the ion exchange membrane is formed to irradiation while the material or materials from which the ion exchange membrane is formed is between the electrodes.
6. The method, according to claim 2 , wherein in situ polymerisation of the monomers or the pre-polymer comprises subjecting the monomers or the pre-polymer to irradiation while the monomers or the pre-polymer is between the electrodes.
7. The method, according to claim 1 , wherein the polymer is a solid polymer electrolyte.
8. The method, according to claim 4 , wherein the electrochemical cell is a fuel cell.
9. The method, according to claim 4 , wherein the electrochemical cell is an electrolyser.
10. The method, according to claim 2 , wherein the polymerisation is free-radical polymerisation.
11. The method, according to claim 2 , wherein the polymerisation is polymerisation by irradiation.
12. The method, according to claim 2 , wherein the polymer is a solid polymer electrolyte, and wherein the polymerisation is free-radical polymerisation.
13. The method, according to claim 2 , wherein the polymer is a solid polymer electrolyte, and wherein the polymerisation is polymerisation by irradiation.