Polymer dispersion and electrocatalyst ink
A polymer dispersion comprising one or more proton-conducting polymer materials in a liquid medium, and an electrocatalyst ink comprising one or more electrocatalyst materials and one or more proton-conducting polymer materials in a liquid medium are disclosed. The polymer dispersion and the electrocatalyst ink further comprise a protic acid. Electrocatalyst layers, gas diffusion electrodes, catalyzed membranes and membrane electrode assemblies prepared using the dispersion and/or the ink are also disclosed.
1. A composition for use in preparing a fuel cell consisting of a dispersion, wherein the dispersion consists of a mineral acid and one or more proton-conducting polymer materials dispersed in a liquid medium, wherein the total amount of organic components in the liquid medium does not exceed 10 wt % and the composition does not include an electrocatalyst material and the mineral acid serves as a proton donor in the composition.
2. A composition according to claim 1 , wherein a ratio of the number of acidic protons in the mineral acid to the number of acidic protons in the one or more proton-conducting polymer materials is at least 0.5.
3. A composition according to claim 1 , wherein the mineral acid is nitric acid or sulphuric acid.
4. A composition according to claim 1 , wherein the one or more proton-conducting polymer materials is one or more perfluorinated sulphonic acid polymers.
5. A composition according to claim 1 , wherein a ratio of the number of acidic protons in the mineral acid to the number of acidic protons on the one or more proton-conducting polymer materials is less than 10.
6. A composition according to claim 5 , wherein the ratio of the number of acidic protons in the mineral acid to the number of acidic protons on the one or more proton-conducting polymer materials is less than 5.
7. A process for preparing the composition according to claim 1 , comprising steps of
a) preparing a dispersion of one or more proton-conducting polymer materials in a liquid medium, wherein the total amount of organic components in the liquid medium does not exceed 10 wt %; and
b) adding a mineral acid to the dispersion.
8. A process for preparing the composition according to claim 1 , comprising steps of
a) adding a mineral acid to a dispersion of one or more proton-conducting polymers in a liquid medium; and
b) adjusting the total amount of organic components in the liquid medium so that the total amount of organic components in the liquid medium does not exceed 10 wt %.
9. A method for incorporating a proton-conducting polymer into an electrocatalyst layer, comprising applying the composition according to claim 1 to an electrocatalyst layer.
10. A method for preparing a gas diffusion electrode wherein the composition according to claim 1 is applied to a pre-formed gas diffusion electrode.
11. A method for preparing a membrane electrode assembly wherein the gas diffusion electrode is prepared according to claim 10 and is combined with a membrane.
12. A method for preparing a catalysed membrane wherein the composition according to claim 1 is applied to a pre-formed catalysed membrane.
13. A method for preparing a membrane electrode assembly wherein the catalysed membrane is prepared according to claim 12 and is combined with a gas diffusion material.
14. A gas diffusion electrode prepared with the dispersion according to claim 1 .
15. A catalysed membrane prepared with the dispersion according to claim 1 .
16. A membrane electrode assembly prepared with the dispersion according to claim 1 .
17. A composition for use in preparing a fuel cell consisting of a dispersion, wherein the dispersion consists of a mineral acid and one or more proton-conducting polymer materials dispersed in a liquid medium, wherein the total amount of organic components in the liquid medium does not exceed 10 wt % and the composition does not include an electrocatalyst material and the composition has a viscosity suitable for application of the composition during the preparation of a fuel cell to form a layer of the fuel cell.
18. A composition according to claim 17 , wherein a ratio of the number of acidic protons in the mineral acid to the number of acidic protons on the one or more proton-conducting polymer materials is less than 10.
19. A composition according to claim 18 , wherein the ratio of the number of acidic protons in the mineral acid to the number of acidic protons on the one or more proton-conducting polymer materials is less than 5.