ELECTRODE BASE MATERIAL AND METHOD FOR PRODUCING SAME

An object of the present invention is to provide an electrode substrate that maintains electrical conductivity and achieves both a high drainage performance and any one of a high gas diffusivity and spring property. To achieve the above-described object, an electrode substrate according to the present invention is an electrode substrate including a carbon fiber sheet having pores filled with a fluoropolymer and carbon fine powder, wherein, in terms of a fluorine/carbon ratio (F/C), the ratio of the smallest value (F/Cmin) to the largest value (F/Cmax) of the average value (F/C-1) in one surface of the electrode substrate, the average value (F/C-2) in the central plane in the thickness direction, and the average value (F/C-3) in the other surface is 0.80 or more, and wherein, in a pore size distribution, the electrode substrate has at least a first peak present in the range of pore size of 0.5 μm or more and less than 120 μm and a second peak present in the range of pore size of 10 nm or more and less than 0.5 μm, and the ratio (V1/V2) of the peak volume (V1) of the first peak to the peak volume (V2) of the second peak is 1.0 to 7.0.