| dc.description.abstract | Fuel cells are attractive alternative energy sources due to their low-to-moderate operating temperature, zero greenhouse emission, and wide range of applications including automobiles and stationary power sources. However, they have key commercialization disadvantages. Proton exchange membrane fuel cells (PEMFCs) produce high power density but require expensive rare noble metal catalysts (e.g., platinum), which impedes PEMFC commercialization. Alkaline fuel cells (AFCs) are unstable and dangerous due to the use of caustic liquid electrolyte; therefore, solid-state membranes are necessary to promote safe, commercial AFCs. In this study, alternative electrode fabrication techniques and alternative hydrocarbon-based polymers as membranes and ionomers were explored to reduce the overall fuel cell cost for PEMFCs and AFCs.
Ultra-low platinum electrodes fabricated via electrospinning/electrospraying (E/E) produced higher PEMFC power density than conventional electrodes and provided insight in the ionomer impact on catalyst particle aggregates. To commercially fabricate E/E electrodes, a needleless electrospinning apparatus was developed in our laboratory. Needleless electrospinning produced proton-conducting nanofibers with higher mechanical and ion transport properties at a higher production rate than needle electrospinning due to multiple higher local polymer concentration sites at the electrospinning surface. Needleless electrospun nanofibers with catalyst particles were employed as ultra-low platinum loading fuel cell electrodes and demonstrated similar power densities as E/E electrodes. These results demonstrate the possibility of producing ultra-low platinum loading E/E electrodes at high production rates.
Commercially available pentablock terpolymers (PTPs) were used as membranes and ionomers in PEMFCs and AFCs. Sulfonated PTPs as membranes and ionomers demonstrated higher conductivity properties and reasonable power densities compared to the commercial fluorinated polymer (Nafion). Brominated and quaternized PTPs with methylpyrrolidinium cations were also developed as solid-state anion exchange membranes and demonstrated promising power densities and durability in AFC applications. Low-platinum E/E electrodes of electrospun PTP nanofibers and electrosprayed catalyst particles demonstrated better platinum utilization than conventional electrodes. The combination of commercial fabrication of ultra-low platinum E/E electrodes and commercially available low-cost ion exchange membranes and ionomers offer an affordable, sustainable, clean energy solution. | en |
