New Fluorinated Ionomers for Enhanced Oxygen Transport in Fuel Cell Cathodes
- Research Fluoropolymer Chemist
This DOE SBIR Phase I program has been successful and Compact Membrane Systems (CMS) has met nearly all and exceeded some of the program key objectives. We have synthesized and characterized a series of new custom amorphous fluoropolymers that are also ionomers and that may have applications in proton exchange membrane (PEM) fuel cells. The ionomers comprise 4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole (PDD), a monomer known for imparting higher free volume and gas permeability in fluoropolymers. As a primary objective, we have demonstrated that certain ionomer compositions have oxygen permeability that was higher than Nafion®, a benchmark ionomer material that is used in the cathode (catalyst) layer of PEM fuel cells. A cathode ionomer has to be proton conductive but also needs to have good oxygen permeability in order for the fuel cell to function at high electrical power output. Even higher power output is desirable in order to lower PEM fuel-cell component costs and accelerate commercial viability. Higher ionomer oxygen permeability was anticipated to help achieve these goals and we have demonstrated that certain CMS ionomer compositions have at least two times higher oxygen permeability than Nafion®, for a similar equivalent weight, under high relative humidity and elevated temperature conditions, which would be encountered in a PEM fuel cell. A milestone objective for this program was to identify and collaborate with a partner for initial screening and possible post phase I fuel cell testing of higher-permeability ionomers. Giner, a PEM fuel cell component developer in Massachusetts and also a SBIR grant recipient, was supplied with a sample of a CMS higher permeability ionomer. Giner reported that their initial results showed that the CMS ionomer has a 100-mV higher cell voltage at current densities at or above 1.8-A/cm2, compared to Nafion®. Giner has indicated that this is a significant result such that they would like to continue working with CMS for a joint phase II proposal and further development of these ionomers. In a phase II program, CMS would supply ionomers for expanded fuel cell testing at Giner while continuing to improve the ionomer molecular weight, yield, and potentially develop even higher permeability ionomers. In summary there are several potential public benefits from successful development of higher permeability ionomers for use in PEM fuel cells. Fuel cells have the potential to be a key power source versus internal combustion engines as part of a future hydrogen-based energy economy. These benefits include: Reduction of polluting carbon dioxide, a greenhouse gas linked to global warming and caused by burning fossil fuels. For PEM fuel cells the only by-product is water at the point of use. Using PEM fuel cells eliminates greenhouse gases over the whole cycle if the hydrogen fuel comes from the electrolysis of water driven by renewable energy. A more greener and sustainable energy economy with greater energy security for the user nation since hydrogen can be produced anywhere where there is water and a source of electrical power.
- Research Organization:
- Compact Membrane Systems, Inc.
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0018537
- OSTI ID:
- 1491717
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- Final Report: DOE-CMS-18537; DOE225
- Country of Publication:
- United States
- Language:
- English
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