Fuel Cell Electrode Inks with Pre-Formed Particle/Binder Fibers
Authors: Fan Xiaozong , Pintauro Peter , Wycisk Ryszard 
Published: December 2024

When fuel cell electrodes are prepared by a conventional spraying or slot-die coating method, there is little or no control over the multi-scale organization of catalyst particles and polymer binder. Electrode structural features such as particle and binder interconnectivity, macro-porosity, and micro-porosity are difficult to control but are critically important when high-performance nanocatalysts are used. Nanofiber electrospinning is an electrode fabrication technique that can address fuel cell electrode morphology issues for next-generation MEAs. As a commercial fabrication method, electrospinning has been shown to be scalable, robust, and cost-effective, especially for the creation of non-woven mats of sub-micron-diameter polymer fibers. Electrospinning can also be used to prepare particle/polymer fiber networks with intra- and inter-fiber porosity. Such fiber mats have been used as the electrode material in Li-ion batteries, H2/Br2 redox flow batteries, and H2/air proton-exchange membrane fuel cells [1-4].

Recent work on nanofiber electrodes at Vanderbilt has focused on inks containing pre-formed electrospun catalyst/binder fibers. With such inks, nanofiber electrode MEAs can be made using commercial roll-to-roll fabrication lines. For this poster presentation, experimental results will be presented on nanofiber mat electrode MEAs with Pt/C catalyst and Nafion™ binder. Procedures for preparing inks with nanofibers and then using the inks to create CCMs or GDEs will be shown. Fuel cell performance and durability results with the resulting MEAs will be contrasted with fuel cell data where the electrodes are made directly from electrospun mats, i.e., by the direct transfer of a mat from the electrospinner to a GDL or membrane, and made using a conventional catalyst powder + binder ink. The effects of catalyst loading and fuel cell operating conditions on fuel cell power output before and after a metal dissolution accelerated stress tests will also be presented. For example, an MEA with a Nafion 211 membrane and electrodes made using an ink with pre-formed fibers (TKK Pt/C catalyst at 0.13 mg/cm2 for the anode and 0.20 mg/cm2 for the cathode) generated 0.99 W/cm2 at 0.7 V, at 100% RH, 80oC, and 3 atmabs total pressure with gas feeds of H2 and air.

Acknowledgment

This work was funded by the U.S. Department of Energy’s Hydrogen and Fuel Cell Technologies Office, Fuel Cell Performance and Durability Project, under contract No. DE-EE0007653.

References

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