FUEL CELL GAS DIFFUSION LAYER AND METHODS FOR PRODUCING THE SAME

A fuel cell gas diffusion layer comprising a porous carbon fiber base substrate containing discontinuous carbon fibers bonded to each other with carbide and a porous layer containing at least carbonaceous particles, the porous carbon fiber base substrate having a porous layer (A) with a mean thickness t1 of 10 to 55 µm deposited on one surface, namely surface A, thereof, the porous carbon fiber base substrate being impregnated with porous layer (J) at least part of which is exposed at the opposite surface, namely surface B, the porous carbon fiber base substrate holding internal pores having a through-thickness cross-section area accounting for 5% to 40%, at least porous layer (A) and porous layer (J) both having a percentage of void of 50% to 85%, the porous carbon fiber base substrate having a thickness of 60 to 300 µm, and the porous carbon fiber base substrate having a bulk density of 0.20 to 0.45 g/cm 3 .