New Approaches to Improved PEM Fuel Cell Catalyst Layer

Polymer-electrolyte membrane (PEM) fuel-cells are one of the most promising energy conversion technologies for renewable clean energy applications- A major challenge preventing the widespread use and commercialization of PEM fuel cells is achieving high performance with low-loadings of platinum group metal (PGM) catalysts- One of the factors driving performance limitations in the cell is the mass transport losses within the cathode catalyst layers (CCL) due to sluggish oxygen-reduction reactions occurring at the platinum-ionomer interface- The role of the ionomer in CCL is to provide transport pathways for protons and molecular oxygen so they could meet the electrons and react at the platinum interface- Any resistance to transport of these ionic and gaseous species within the CCL results in mass-transport limitations and performance losses, especially at high current densities- It is known that mass-transport losses increase with reduced platinum loading, thereby creating a performance-cost tradeoff for fuel cells- It is of great interest to understand these transport losses for low-loaded catalyst layers and mitigate them using engineering ionomer materials in order to achieve sustainable cell performance without sacrificing the cost targets- A viable solution to reduce the transport resistances in the catalyst layers is to create new ionomers that can provide good ion and oxygen transport needed to accomplish high- performing fuel cell catalysts- Characterization of transport properties of ionomers for various molecular architectures is the key step, in the effort to create and identify the optimized polymer structure with improved transport- Using this approach, we propose to develop, optimize, and demonstrate improved fuel cell catalyst ionomers based on new molecular architectures that will have dramatic improvements compared to current ionomers such as PFSA materials through a combination of higher conductivities, improved water permeability, increased oxygen and hydrogen permeabilities to reduce the mass transport related resistance observed all while continuing to be compatible with other ionomer materials including PFSA exhibiting durability and minimizing the potential for adsorption on platinum-