Patent ID: 8309265

Claim:
An electrolyte membrane for a fuel cell comprising a cluster of minute projections on both sides of a polymer electrolyte membrane, wherein the minute projections, of the cluster of minute projections, are formed with a prescribed shape with a planar surface, wherein the minute projections, of the cluster of minute projections, are pillar-shaped, and wherein a height of the cluster of minute projections on one side of the electrolyte membrane is different from a height of the cluster of minute projections on the other side of the electrolyte membrane; wherein a pitch between the minute projections is from 1 μm to 20 μm, said pitch being a distance between centers of adjacent minute projections; wherein a ratio (H/D) of a height (H) to a corresponding diameter (D) of the minute projections is larger than 1; and wherein the pitch between minute projections is from 1 to 20 times the diameter of the minute projections.