Patent ID: 7592092

Claim:
A fuel cell having at least a membrane electrode assembly comprising: an electrolyte membrane; a hydrogen electrode-side catalyst layer formed on one side thereof; and an air electrode-side catalyst layer formed on the other side thereof, wherein a porosity of the hydrogen electrode-side catalyst layer is lower than a porosity of the air electrode-side catalyst layer, a volume of pore space of the hydrogen electrode-side catalyst layer has a range of 1.0% to 3.0% of a total volume of the catalyst layer, and a volume of pore space of the air electrode-side catalyst layer has a range of 3% to 30% of the total volume of the catalyst layer, wherein the hydrogen electrode-side catalyst layer contains an additive having an average particle diameter less than or equal to 0.3 μm and the porosity of the hydrogen electrode-side catalyst layer is lower than the porosity of the air electrode-side catalyst layer, and wherein the additive is selected from titanium oxide, zinc oxide, and cerium oxide.