Invited: Corrugated Cell Structures in Membrane Electrode Assemblies

Abstract

The traditional Proton Exchange membrane fuel cell stack with its bipolar plates with grooved flow channels,flat membrane electrode assemblies (MEAs), seals and end-plates has been the dominantmethod of construction of multi kW fuel cells for the past 40 years. Smaller sub-watt andportable applications have explored novel cell design variations such as “jelly roll”concepts but none have been able to achieve the power density of the traditionalstacked plate design. The primary reason for this is the efficient collection of the currentand the compact packing of the MEAs. However at the present time one of the most challenging aspects of traditional PEM fuelcell stacks is the difficulty to achieve the platinum catalyst utilization target of 0.2 gPt/kWe set forth by DOE. Good catalyst utilization can be achieved with state-of-theartcatalyst coated membranes (CCM) when ultra-low catalyst loadings (< 0.1 mg/cm2)are used at lower current. Unfortunately when ultra-low loadings are used, the peakpower density is lower as compared to conventional loadings. Thus a larger totalactive area and a larger bipolar plate is needed which results in a lower overall stackpower density and as such the DOE targets of power density can not be achievedsimultaneouslyWe thus now introduce in this proposal, our novel concept to increase the available MEAactive area by 2x or more while maintaining the same bipolar plate size. This isachieved via a corrugated MEA sandwiched between bipolar plates. This is much likecorrugated cardboard, where the center corrugation (or flute) is the MEA. Thecorrugations then form the gas channels thus there is no need for forming flow fieldchannels in the bipolar plates. Thus the gas diffusion media as well as the membrane needs to be formed in the corrugated structure. We will describe the state of our development on this approach.