A growing number of portable consumer electronics need a small, lightweight power supply with high capacity. Miniaturized fuel cells can meet this demand. A polymer electrolyte fuel cell (PEFC) typically consists of two electrodes, separated by a polymer electrolyte membrane, two current collectors and two sets of flow channels for the reactants all mounted together in a housing. The current collector or diffusion layer is usually made from carbon paper or carbon cloth. The carbon fibers lead the electric current and the pores allow for transport of the reactants. The focus of the investigations presented here is the miniaturisation of the macroscopic flow fields in fuel cells in order to achieve higher energy densities. Three concepts of fuel cells with micro-structured flow fields are presented, amongst them one complete fuel cell system for the use in portable applications. Since different packaging and assembly techniques with flexible materials are being used, the form of the cell can be tailored for specific applications. A stack of cells can be very flat resulting in power densities as high as 1 W/cm3.
KeywordsFuel Cell Current Collector High Energy Density Polymer Electrolyte Membrane Carbon Paper
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