Porous carbon sheet and its precursor fiber sheet

The present invention provides a porous carbon sheet having high mechanical strength and less appearance defects， and a precursor fiber sheet for obtaining the same， even when the bulk density of the porous carbon sheet is lowered in order to increase gas diffusibility and drainage. The present invention relates to a precursor fiber sheet comprising short carbon fibers having an average length of 3 to 10 mm， natural pulp having an ash content of 0.15% by mass or less， and resin carbonized by heat treatment， and a porous carbon sheet obtained by carbonizing the same. In order to increase gas diffusion properties and water draining properties， the present invention provides: a porous carbon sheet which exhibits high mechanical strength even when the bulk density of the porous carbon sheet is reduced and which has few appearance defects; and a precursor fiber sheet for obtaining the porous carbon sheet. The present invention is the following: the precursor fiber sheet that contains short carbon fibers having an average length of 3-10 mm， natural pulp having an ash content of 0.15 mass % or lower， and a resin that is carbonized through heat treatment; and the porous carbon sheet obtained by carbonizing the precursor fiber sheet. In order to increase gas diffusion properties and water draining properties， the present invention provides: a porous carbon sheet which exhibits high mechanical strength even when the bulk density of the porous carbon sheet is reduced and which has few appearance defects; and a precursor fiber sheet for obtaining the porous carbon sheet. The present invention is the following: the precursor fiber sheet that contains short carbon fibers having an average length of 3-10 mm， natural pulp having an ash content of 0.15 mass % or lower， and a resin that is carbonized through heat treatment; and the porous carbon sheet obtained by carbonizing the precursor fiber sheet.