Carbon paper flow fields made by WEDM for small fuel cells

Abstract

While the focus of our preceding investigations, presented on the last HARMST 2001 in Baden Baden, was the miniaturization of fuel cells in order to increase their power density, the current activities at the IMTEK concentrate on the identification of processes that have the potential to lower the production costs of those miniaturised fuel cells. As a novel approach, we replaced the commonly used backing layer and flow fields made from graphite or steel by a flow field with micro channels structured in carbon paper. A micrograph of these structures is shown in Figure 1. For the first time, such structures were produced using Wire Electro Discharge Machining (WEDM). With our proven cell setup [1], we reach energy densities comparable to the system we presented at the last HARMST 2001, while being able to produce the cells at considerably lower costs. Another major advantage of the use of graphitic materials is that the cell is no longer prone to corrosion.