High thermal conductivity electrode substrate

Abstract

An electrode substrate is disclosed that includes a plane and a through-plane direction. First and second carbon fibers are respectively arranged in the plane and through-plane direction. The substrate includes a thickness in the through-plane direction and the second fiber has a length less than the thickness. The first carbon fiber has a length greater than the thickness. In one example method of manufacturing the example substrate, PAN-based carbon fibers are blended with meso-phase pitch-based carbon fibers. A resin is applied to a non-woven felt constructed from the carbon fibers. The felt and resin are heated to a desired temperature to achieve a desired through-plane thermal conductivity.

Description

technical field

[0001] The present disclosure relates to carbon-carbon composite materials suitable for use as substrates in fuel cells, for example. Background technique

[0002] Some types of fuel cells, such as proton exchange membrane and phosphoric acid fuel cells (PEMFC and PAFC), use porous carbon-carbon composite materials as electrode substrates, also known as gas diffusion layers. In US Patent 4,851,304, an exemplary fuel cell substrate and fabrication process is shown.

[0003] A typical method of making the substrate includes: (1) forming a nonwoven mat from chopped carbon fibers and a temporary binder through a wet-laid papermaking process; (2) impregnating or pre-impregnating the substrate with a phenolic resin dissolved in a solvent. felt, followed by solvent removal without curing the resin; (3) pressing one or more layers of felt to a controlled thickness and porosity at a temperature sufficient to cure the resin; (4) heat treating the felt in an inert atmo...

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