Membrane/electrode assembly for polymer electrolyte fuel cell
View Patent ↗A membrane electrode assembly less susceptible to flooding or shortcircuiting caused by piercing of carbon fibers of a gas diffusion layer to a polymer electrolyte membrane is provided, containing a cathode having a catalyst layer and a gas diffusion layer, an anode having a catalyst layer and a gas diffusion layer, and a polymer electrolyte membrane interposed between the catalyst layer of the cathode and the catalyst layer of the anode, wherein each of the cathode and the anode further has a protective layer containing carbon fibers having an average fiber diameter of from 1 to 30 μm and a fluorinated ion exchange resin, between the catalyst layer and the gas diffusion layer, and the mass ratio (F/C) of the fluorinated ion exchange resin (F) to the carbon fibers (C) contained in the protective layer is from 0.05 to 0.30.
1. A membrane/electrode assembly for a polymer electrolyte fuel cell, comprising:
a cathode having a catalyst layer and a gas diffusion layer,
an anode having a catalyst layer and a gas diffusion layer, and
a polymer electrolyte membrane interposed between the catalyst layer of the cathode and the catalyst layer of the anode, wherein
each of the cathode and the anode further has a protective layer comprising carbon fibers having an average fiber diameter of from 1 to 30 μm and a fluorinated ion exchange resin, between the catalyst layer and the gas diffusion layer, and
the mass ratio (F/C) of the fluorinated ion exchange resin (F) to the carbon fibers (C) contained in the protective layer is from 0.05 to 0.30.
2. The membrane/electrode assembly for a polymer electrolyte fuel cell according to claim 1 , wherein the protective layer has a thickness of from 15 to 80 μm.
3. The membrane/electrode assembly for a polymer electrolyte fuel cell according to claim 1 , wherein the fluorinated ion exchange resin contained in the protective layer has an ion exchange capacity of from 0.5 to 2.0 meq/g dry resin.
4. The membrane/electrode assembly for a polymer electrolyte fuel cell according to claim 1 , wherein the fluorinated ion exchange resin contained in the protective layer is a perfluoropolymer having ion exchange groups.
5. The membrane/electrode assembly for a polymer electrolyte fuel cell according to claim 1 , wherein at least one of the cathode and the anode further has a bond drainage layer comprising carbon fibers having an average fiber diameter of from 1 to 200 nm between the catalyst layer and the protective layer.
6. The membrane/electrode assembly for a polymer electrolyte fuel cell according to claim 5 , wherein the bond drainage layer has a thickness of from 2 to 15 μm.
7. The membrane/electrode assembly for a polymer electrolyte fuel cell according to claim 5 , wherein the bond drainage layer further contains a fluorinated ion exchange resin.
8. The membrane/electrode assembly for a polymer electrolyte fuel cell according to claim 7 , wherein the mass ratio (f/c) of the fluorinated ion exchange resin (f) to the carbon fibers (c) contained in the bond drainage layer is from 0.05 to 2.
9. The membrane/electrode assembly for a polymer electrolyte fuel cell according to claim 1 , wherein at least one of the cathode and the anode further has a microporous layer comprising carbon particles, between the protective layer and the gas diffusion layer.