This Small Business Innovation Research (SBIR) Phase II project addresses the need in the marketplace for fuel cells with improved durability. Polymer electrolyte membrane (PEM) fuel cells offer a potential environmentally friendly source of power, but performance improvements are required before costs justify more widespread adoption of this technology. Catalyst deactivation limits the lifetime of commercial PEM fuel cells, as the catalyst support is subject to oxidation and the active metal component, typically containing platinum, sinters during use. This Phase II project addresses both of these problems. Through a combination of new technologies from the ceramics, electronics, and catalyst industries, the feasibility of producing new support materials that are much more resistant to degradation has earlier been demonstrated. Accelerated aging studies have shown dramatic increases in catalyst lifetime, as much as tenfold. Building on these successes, the goals of this Phase II project are development of an optimized process for preparation of this new catalyst system and the production of prototype commercial fuel cell power packs with this new catalyst system. These prototype devices will be tested to demonstrate if the improvements shown in accelerated aging studies translate into longer lifetimes in commercial products.
The broader/commercial impact of this project complements the work reported by others in developing fuel cell catalyst systems with higher activity. Fuel cell systems that combine catalysts with high activity and long lifetime lead to the best overall economics. Fuel cell powered systems also have environmental advantages. The use of fuel cells to generate power leads to a significant reduction in greenhouse gas emissions if they replace systems powered by internal combustion engines. Reductions in emissions as high as 25% have been achieved when fuel cell power supplies replace internal combustion powered systems. The technology to be developed can be used in other applications where attack of a carbon substrate under oxidizing conditions leads to degradation which occurs not only in a variety of catalyst applications but also in electrodes for battery applications.
This Phase II project was to improve the durability of polymer electrolyte membrane fuel cells. Polymer electrolyte membrane fuel cells offer a potential environmentally friendly source of power but performance improvements are required before costs justify more widespread adoption of this technology. This project focuses on improvement of long-term performance of platinum or other noble metal based catalysts for fuel cells. Loss of active platinum surface area during the course of operation is one of the major reasons for performance degradation. To counteract this loss of active metal area this proposal provides a unique approach to stabilization of the catalyst, via modification of the carbon support. New technology from ceramics, the electronics industry and catalysis are combined to develop new support materials which are much more resistant to degradation. During our Phase II program we accomplished a number of objectives including; Scaling up the synthesis of our modified carbons, improving the durability of our catalysts via optimization of calcination procedures, identification of the structure of our protective layer at the atomic scale, and testing of additional precursors for the formation of our protective layer on carbon. The most significant result is that the newly developed catalyst supports show dramatic improvements in lifetime compared to unmodified carbon supports. Accelerated aging studies, performed in a commercial fuel cell test stand, show more than a ten-fold increase in lifetime. This dramatic improvement in lifetime could lead to significantly better overall economics. Optimization of this new catalyst system and testing in a commercial device were crucial parts of this project. Long term testing will help verify if the results we observe in the lab, during accelerated aging tests, translate into increased durability in a commercial fuel cell stack. We have stated this program but the final results are not yet available.
