Direct Methanol PEM Fuel Cell Power Source with Advanced Composite Membrane

The fuel cell system receiving significant attention for transportation applications is the proton-exchange membrane fuel cell (PEMFC) which uses a hydrated sheet of a perfluorinated ion-exchange membrane as a solid electrolyte in the fuel cell. The liquid feed direct methanol PEMFC, because of its simplicity (no reformer, simple heat management) and inherent reliability (ionomer membrane flooded with water), is a potentially attractive power source for vehicles and other low-to medium-power applicatoins, in both the commercial and military sectors. One drawback to direct methanol PEMFCs is that the methanol permeates across currently available PEM electrolytes from the anode to the cathode where it reacts with air (O2), resulting in parasitic loss of methanol and reduced fuel cell voltage. To overcome this problem, development of an efficient unitized composite PEM containing an integral, thin low-water-content surface ionomer film bonded to standard Nafion 117 membrane is proposed. This structure is expected to minimize methanol permeability while maintaining high proton transport, leading to increased fuel cell power output and improved system efficiency. Anticipated Benefits: Vehicles powered by direct methanol fuel cells have the potential for a very large market in California, the New England states, and other states in the Northeast that have mandated the introduction of zero-emission vehicles by the end of the decade. Another potential commercial application is dispersed power generators. Military applications include standard vehicles, unmanned underwater and air vehicles, and person portable back-pack power supplies.