Importance

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Abstract

An improved porous support layer is disclosed for use in an electrochemical cell such as a fuel cell having a proton exchange membrane ('PEM') as an electrolyte. In a preferred embodiment the porous support layer is positioned near and in fluid communication with an electrode to facilitate fluid transport to and away from each electrode. Each such porous support layer includes hydrophobic pores and hydrophilic pores integrated throughout the layer, wherein the hydrophobic pores are coated with a hydrophobic substance and include about 75 percent to about 95 percent of the total pore volume of the porous support layer, and the hydrophilic pores comprise about 25 percent to about 5 percent of the total pore volume of the porous support layer. The hydrophobic pores of the porous support layers facilitate gas transfer and restrict liquid water absorption into the hydrophobic pores, while the hydrophilic pores facilitate simultaneous liquid water transport through the layers. A method of manufacture of the porous support layer includes the steps of filling about 25 percent to about 5 percent of the pore volume of a carbon fiber substrate layer with a blocking material; applying a hydrophobic substance to the remaining, unfilled pore volume of the substrate layer; and heat treating the dried substrate at a temperature adequately high to volatilize or decompose the blocking material and fuse the hydrophobic substance to coat the hydrophobic pores to produce the porous support layer.

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First Claim