Current proton exchange membranes (PEM) are based on polymeric materials such as perfluorosulfonic acid (Nafion). The operation of these membranes is presently limited to below 100C due to the required presence of water (50% relative humidity or above) to obtain high proton conduction. This precludes the efficient use of current PEMs in fuel cells for transportation where operating temperatures of 120C and above are required. Therefore, to overcome these limitations, this project will focus on the development of new advanced ceramic PEM materials that can operate at intermediate temperatures (above 120C) and low partial pressure of water vapor.
Intellectual Merit: Based on recent crystallographic insights and the current understanding of proton conduction in ceramics, this project will synthesize compounds in the family of pyrophosphates AP2O7 (A = Sn,Zr,Ti); it will investigate their proton conductivity and assess their potential as membrane materials for the next generation of PEM fuel cells. The objectives of the proposed research can be summarized as follows: (a) synthesize advanced pyrophosphate ceramics for proton conduction membranes; (b) characterize the conductivity of the synthesized materials and determine the proton conduction mechanisms operating in these ceramics; and (c) evaluate their potential as proton electrolyte membranes for PEM Fuel Cells. Specifically, acceptor-doped ceramics will be synthesized; their crystal structure, composition, and microstructure will be characterized; proton conducting membranes will be fabricated and their electrical conductivity will be measured. Finally, the effective proton conductivity of the most promising membrane materials will be measured as a function of temperature and atmosphere (partial pressure of H2, moisture, etc.) to assess the performance of the developed proton electrolyte compounds. The uniqueness of the proposed research lies in the rational design and development of an advanced intermediate-temperature PEM material based on merging the field of crystallographic design (crystal structure tailoring) and the recent understanding of the proton conduction mechanisms in oxide ceramics. As such, the research proposed has the potential for a breakthrough development in novel PEM materials rather than an incremental enhancement in the properties.
Broader Impacts: As part of this project the PIs will organize and participate in local, national, and international activities with both technical and non-technical audiences to disseminate fact and knowledge-based information about alternative energy sources and technologies, with special emphasis given to fuel cells. Specifically, this will be achieved by: a) Organizing an "Alternative Energy" station within Engineering Extravaganza, a local showcase of projects and demonstrations open to the general public as part of the yearly Engineers Week activities; (b) Including a module on fuel cells in a departmental program at with nation-wide participation, and (c) Incorporating Fuel Cells as a topic in the Electroceramics Workshops that the PI is currently organizing across the Bolivarian countries in South America.