(487b) Electrospun Particle/Polymer Fiber Mats As Fuel Cell and Battery Electrodes

Electrospinning is gaining popularity as a convenient, robust, and scalable technique for fabricating non-woven mats of sub-micron diameter polymer fibers. Although not as well studied, the technique can also be used to prepare particle/polymer fiber networks with high intra- and inter-fiber porosity. Such fibrous mats can be used as porous electrodes in fuel cells and batteries, where a high electrode/electrolyte interfacial area is needed. In the present talk, recent experimental work on new nanofiber mat compositions and architectures for hydrogen/air fuel cell cathodes and lithium-ion battery electrodes will be presented. The fuel cell work is focused on high particle content fibers containing Pt/C or Pt-alloy catalyst powder and a polymer binder based on Nafion^® perfluorosulfonic acid. The fuel cell power output using such a cathode is very high for a low Pt loading (0.10 mg/cm²), near 1.0 W/cm² for H₂/air feeds. Additionally, the fiber mat cathodes exhibit excellent durability, as determined by power losses after accelerated voltage cycling tests. For Li-ion battery applications, single and dual fiber anode mats have been prepared and evaluated, where the fibers contain a polymer binder (e.g., poly(acrylic acid), polyamidimide, or polyvinylidene fluoride), Si nanoparticles as the electrochemically active material, and carbon powder as an electron conductor. Here, the gravimetric and areal capacities of the fiber anode are considerably higher than those for a conventional slot-die coated slurry anode. Inter-fiber voids allow for volume changes in Si during lithiation/delithiation, thus minimizing capacity fade during charge/discharge cycling (up to 1,000 cycles). Experimental details for both fuel cell and battery electrodes will be presented in this talk, including electrospinning procedures, fiber mat characterization data, and device performance.