Pressing Process for the Production of Thin Graphite Compound Bipolar Plates for High-Performance Applications

Abstract

AbstractProton exchange membrane (PEM) fuel cells generate electric current by means of the reactants hydrogen or methanol and oxygen, emitting only heat and water or water vapor. Fuel cells therefore represent a possible technological option for a CO2-neutral energy supply. A core component of fuel cells are bipolar plates (BPP) which are stacked alternately with membrane electrode assemblies (MEA) to form fuel cell stacks. The BPP must ensure leakage-free supply of the fuel gas and oxidation gas to the MEA and removal of the reaction products (electric current, heat and water). One approach to produce thin BPP sheets with high dimensional fidelity at a high quality and dimensional accuracy is hot pressing of graphite compound which, however, offers only limited productivity due to long process times. This paper presents a proof of concept for pressing thin BPP made of highly filled graphite compound, with wall thicknesses down to 0.3 mm, at a low temperature. For the experimental investigations, a multi-part press tool was developed for bipolar half plates (BP-HP) with a size of 540 × 140 mm and designed for high performance applications. The various challenges for forming with regard to material, BPP and die design as well as first pressing parameters such as pressure and temperature were investigated in a proof of concept.KeywordsPressingBipolar plateFuel cell