Method for producing membrane electrode assembly
The present invention relates to a Membrane Electrode Assembly (MEA) which significantly enhances power density as well as structural reliability and method for producing the same. More specifically, it relates to the Membrane Electrode Assembly which has a plurality of protuberances and method for producing the same. The present invention involves making supporting bodies to have a plurality of protuberances on one side of the supporting bodies, forming a catalyst layer on one side of the supporting bodies having the protuberances, interposing a polymer-electrolyte-membrane between the supporting bodies, aligning the supporting bodies for the protuberances to engage each other; and hot-pressing the aligned supporting bodies. The present invention can increase the area of a three-phase boundary in which oxidation-reduction reaction of hydrogen and oxygen occurs and decrease resistance to ion conduction; consequently fuel cells have the characteristic of a large output of power density.
1. A method for producing a membrane electrode assembly generating electric current by electric chemical reaction comprising the steps of:
(a) forming a plurality of protuberances on one side of supporting bodies;
(b) forming a catalyst layer on one side of said supporting bodies on which said plurality of protuberances are formed;
(c) interposing a polymer electrolyte membrane between said supporting bodies;
(d) aligning said supporting bodies for said protuberances to engage each other; and
(e) hot-pressing said supporting bodies;
wherein a three phase boundary corresponding to said protuberances is formed;
wherein said (d) step is performed by inserting aligning members into pre-formed aligning halls; and
wherein said aligning member has a plurality of protrusions different in size and height.
2. The method of claim 1 , wherein said (a) step further comprises the steps of:
coating one side of said supporting bodies with a dry film;
exposing the one side of said supporting bodies;
developing said dry film; and
etching the one side of said supporting bodies physically.
3. The method of claim 2 , wherein said dry film is developed by a spraying developer.
4. The method of claim 2 , wherein said supporting bodies are etched by a sand blaster.
5. The method of claim 2 , wherein the etching depth is hundreds of micrometers.
6. The method of claim 2 further comprising the step of combining a plate to the one side of said supporting bodies on which said protuberances are formed.
7. The method of claim 1 , wherein said (a) step is performed by press processing.
8. The method of claim 1 , wherein said (b) step is performed by spraying the one side of said supporting bodies with a catalyst mixed liquid by rotating said supporting bodies.
9. The method of claim 1 , wherein said (c) step is performed by spraying the one side of said supporting bodies with a polymer electrolyte liquid.
10. The method of claim 1 , wherein said (e) step is performed by inserting a spacer between said supporting bodies to uniform thickness of the polymer electrolyte membrane.
11. The method of claim 1 , wherein said protuberances are at least one selected from a quadrangular prism, a triangular prism, a trapezoid prism, a hexahedron, and a quadrangular prismoid.
12. The method of claim 1 , wherein an aspect ratio of said protuberances is from 0.01 to 6.
13. The method of claim 1 , wherein an aspect ratio of said protuberances is from 0.05 to 3.
14. The method of claim 1 , wherein a width of said protuberances is from 50 μm to 500 μm.
15. The method of claim 1 , wherein a width of said protuberances is from 100 μm to 200 μm.
16. The method of claim 1 , wherein a thickness of the polymer electrolyte membrane is from 10 μm to 200 μm.