Electrode utilizing fluorinated carbon
A fluorinated carbon based gas diffusion layer for use in hydrogen and oxygen electrodes. The fluorinated carbon based gas diffusion layer provides for uniform distribution of hydrogen or oxygen across the electrode while maintaining a high level of hydrophobicity within the gas diffusion layer.
1. In a fuel cell, an electrode comprising:
a fluorinated carbon based gas diffusion layer having a built in hydrophobicity; and
an active material layer adjacent to said gas diffusion layer wherein said active material layer comprises a carbon matrix including a redox couple selected from the group consisting of a Co +2 —Co +3 couple, a Co +2 —Co +4 couple, a Ni +2 —Ni +3 couple, a Ni +2 —Ni +4 couple, a Ag—Ag + couple, a Ag—Ag +2 couple, a Cu—Cu +2 couple, a (Ni/Ag) +2 —(Ni/Ag) couple, a (Ni/Fe) oxide +2 —(Ni/Fe) oxide +3 couple, a Mn +2 —Mn +3 —Mn +7 couple, a Sn +2 —Sn couple, and combinations thereof.
2. The electrode according to claim 1 , wherein said gas diffusion layer comprises a plurality of fluorinated carbon particles.
3. The electrode according to claim 2 , wherein said fluorinated carbon particles are 19 to 68 weight percent fluorinated.
4. The electrode according to claim 3 , wherein said plurality of fluorinated carbon particles are at least partially coated with a hydrophobic component.
5. The fuel cell oxygen electrode of claim 4 , wherein said hydrophobic component comprises polytetrafluoroethylene (PTFE).
6. The electrode according to claim 4 , wherein said gas diffusion layer includes 10 to 25 percent by weight of said hydrophobic component.
7. The electrode according to claim 4 , wherein said gas diffusion layer has a gas contacting surface and an electrolyte contacting surface.
8. The electrode according to claim 7 , wherein said hydrophobic component is continually graded from a high concentration at said electrolyte contacting surface of said gas diffusion layer to a low concentration at said gas contacting surface of said gas diffusion layer.
9. The electrode according to claim 7 , wherein said fluorinated carbon particles are continually graded throughout said gas diffusion layer from a high fluorine concentration at said electrolyte contacting surface of said gas diffusion layer to a low fluorine concentration at said gas contacting surface of said gas diffusion layer.
10. The electrode according to claim 1 , wherein said carbon matrix comprises a plurality of carbon particles.
11. The electrode according to claim 10 , wherein said plurality of carbon particles are at least partially coated with polytetrafluoroethylene.
12. The electrode according to claim 11 , wherein said plurality of polytetrafluoroethylene coated carbon particles contains 15 to 25 percent polytetrafluoroethylene by weight.
13. The electrode according to claim 10 , wherein said carbon matrix further comprises 0 to 30 percent by weight of a peroxide decomposer.
14. The electrode according to claim 13 , wherein said peroxide decomposer is selected from a group consisting of MnO 2 , MnO, cobalt oxides, nickel oxides, iron oxides, and mixtures thereof.
15. The electrode according to claim 1 , wherein said carbon matrix comprises a plurality of fluorinated carbon particles.
16. The electrode according to claim 15 , wherein said plurality of carbon particles are at least partially coated with polytetrafluoroethylene.
17. The electrode according to claim 16 , wherein said plurality of polytetrafluoroethylene coated carbon particles contains 15 to 25 percent polytetrafluoroethylene by weight.
18. The electrode according to claim 15 , wherein said carbon matrix further comprises 0 to 30 percent by weight of a peroxide decomposer.
19. The electrode according to claim 18 , wherein said peroxide decomposer is selected from a group consisting of MnO 2 , MnO, cobalt oxides, nickel oxides, iron oxides, and mixtures thereof.
20. The electrode according to claim 1 , further comprising:
a first current collector grid disposed adjacent to said gas diffusion layer opposite said active material layer; and
a second current collector grid disposed adjacent to said active material layer opposite said gas diffusion layer.
21. The electrode according to claim 20 , wherein said first current collector grid and said second current collector grid each comprise at least one selected from the group consisting of mesh, grid, matte, expanded metal, foil, foam, plate, and combinations thereof.