Summary
Porous conducting carbon fiber‐based composite paper is used as an electrode backing in the fuel cell assembly. It not only acts as a channel through which the reactant and product gases pass to and from the bipolar plate and the catalyst site but also helps in the flow of electrons. In order to perform its role efficiently, it should have sufficient strength, high electrical conductivity, and ideal porous structure. Carbon paper has been fabricated, which builds up the required composite properties. Studies have been conducted to optimize the fiber/matrix ratio in the carbon paper, while ensuring the perfect combination of porosity, mechanical strength, and electrical conductivity for an electrode in a proton electrolyte membrane fuel cells. Detail physico‐mechanical and electrochemical characterizations further ascertain that the fiber/matrix ratio plays an important role in tuning the composite properties. The polarization curve of the unit proton exchange membrane (PEM) fuel cell (with an effective electrode area 4 cm2) shows a peak power density of 916 mW/cm2 for the sample with fiber/matrix ratio of 65:35, which is almost the same as the commercially available sigracet gas diffusion layer (SGL) carbon paper tested under similar conditions. Further, proportionally enlarging the electrode area to 100 cm2 shows that the carbon paper not only shows almost repeatable results in a given set up but also scales up.
Carbon papers (CPs) are used as an electrode backing in PEMFC. It assists the diffusion of both the reactant gases and products toward and from the reaction site and aids the flow of electrons. CP is a carbon/carbon composite made by patterning of carbon fibers in the form of highly porous sheets called preforms, followed by composite formation. Different pore formers have been incorporated into the CP, and their effect on porosity, permeability, structure, and electrical conductivity have been analyzed and found to be significant. The unit PEMFC shows a peak output power density of 797.2 and 756.8 mW/cm 2 with camphor and urea as pore formers, compared to 576.2 mW/cm 2 obtained using the paper prepared without pore former. The effect of pore formers on the separate sections of the polarization curves has been discussed. Further, samples with urea and camphor show comparable performance with the commercial SGL paper.
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