When MEAs are made by a decal, catalyst-coated-membrane, or catalyst-coated GDL method, there is little or no control over the macro-scale organization of the catalyst and binder. Thus, the high ORR catalytic activity of Pt-based catalysts seen in rotating disk experiments is rarely observed in an operating fuel cell MEA. Features such as particle and binder interconnectivity, macroporosity, and microporosity become more critical when high-performance nanomaterial catalysts are employed in fuel cell electrodes. Consequently, new electrode fabrication techniques are needed for next-generation MEAs. Nanofiber electrospinning is just such a method, which can address fuel cell electrode manufacturing and structure/performance issues. As a fabrication method, electrospinning is scalable, robust, and cost-effective, especially for the creation of non-woven mats of sub-micron diameter polymer fibers. Although not as well studied, the method can also be used to prepare particle/polymer fiber networks with high particle loading and high intra- and inter-fiber porosity. Mats from such fibrous materials can be used as electrodes in fuel cells [1-4], batteries [5,6], and capacitors [7], where high interfacial electrode area is of prime importance. In this talk, recent experimental work on nanofiber mat cathodes for hydrogen/air fuel cells will be described. Procedures for fabricating high particle-loaded nanofibers containing various Platinum and platinum-alloy catalysts with different polymer binders will be presented. The effects of catalyst type/loading and binder type on cathode mass activity and electrochemical surface area, cathode durability, and fuel cell power output at high and low relative humidity conditions will be discussed.

Acknowledgments

This work was funded by the Fuel Cell Consortium for Performance and Durability, DOE-EERE FC-PAD Project DE-EE0007653.

References

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