Patent ID: 7879505

Claim:
A fuel cell, comprising: 1) a membrane electrode assembly including: i) an electrolyte membrane, ii) an anode formed on a first side of the electrolyte membrane, and iii) a cathode formed on a second side of the electrolyte membrane opposite to the first side; 2) a first gas diffusion layer configured to diffuse a fuel gas to the anode and having a first raised portion; 3) an anode side separator compressed to the anode with the first gas diffusion layer interposed between the membrane electrode assembly and the anode side separator, wherein the anode side separator has a first contact face facing the first gas diffusion layer, wherein the first contact face is formed with a first groove configured to distribute the fuel gas which is to be diffused to the anode, wherein the first raised portion is raised into a first part of the first groove from a surface of the first contact face, wherein a fuel gas passage is formed in a second part of the first groove as a portion of the first groove other than the first part of the first groove occupied with the first raised portion of the first gas diffusion layer, wherein the fuel gas passage has a first cross section; 4) a second gas diffusion layer configured to diffuse an oxidation gas to the cathode and having a second raised portion; and 5) a cathode side separator compressed to the cathode with the second gas diffusion layer interposed between the membrane electrode assembly and the cathode side separator, wherein the cathode side separator has a second contact face facing the second gas diffusion layer, wherein the second contact face is formed with a second groove configured to distribute the oxidation gas which is to be diffused to the cathode, wherein the second raised portion is raised into a first part of the second groove from a surface of the second contact face, wherein an oxidation gas passage is formed in a second part of the second groove as a portion of the second groove other than the first part of the second groove occupied with the second raised portion of the second gas diffusion layer, wherein the oxidation gas passage has a second cross section, wherein the first raised portion and the second raised portion are different from each other in scale such that, the first cross section of the fuel gas passage and the second cross section of the oxidation gas passage are different from each other.