Patent ID: 9692070
Date: 2017-06-27
CPC Classifications: C04B,D21H,H01M,Y02E

Claim:
1. A carbon substrate for a gas diffusion layer, as a porous carbon substrate with first and second surfaces opposite to each other, the carbon substrate comprising: at least two types of carbon fibers having different lengths and randomly disposed to form a non-woven fabric; and a carbide of an organic polymer disposed between the carbon fibers to bind the same, wherein first carbon fibers having shorter lengths are predominantly disposed to be closer to the first surface of the carbon substrate in a thickness direction of the carbon substrate, and second carbon fibers having longer lengths than the first carbon fibers are predominantly disposed to be closer to the second surface of the carbon substrate, so that the carbon substrate has a porosity gradient in the thickness direction of the carbon substrate that increases toward the second surface from the first surface of the carbon substrate, wherein a large pore having a width of 300 μm to 900 μm, and a medium pore or small pore having a width of about 10 μm or greater to less than 300 μm are co-present in the second surface, and a medium or small pore having a width of about 10 μm to about 100 μm is uniformly distributed in the first surface.