Development of a compact 500 W-class direct methanol fuel cell stack

A 71-cell direct methanol fuel cell (DMFC) stack has been developed at Forschungszentrum Julich. The system consists of the stack, a water/methanol tank, a heat exchanger, a pump and compressors as auxiliary components. The auxiliary components are driven by the DMFC stack itself without external power sources. The DMFC stack consists of 71 cells with an area of 144 cm(2). The current collectors are manufactured of stainless steel (1.4571) with a cell pitch (distance between two membrane electrode assemblies (MEAs)) of only 2 mm. The MEAs are fabricated in-house by a combination of a decal and direct coating method. The thickness of each current collector is 0.3 mm. Each cell is provided with effective flow fields for a homogeneous flow distribution, The flow distribution has been calculated and approved by experiments. Therefore, the necessary stoichiometric air flow rate is only in the range of 2-3. The air compressor is designed to supply air with a maximum pressure of 1.5 bar absolute to the cell. (C) 2002 Elsevier Science B.V. All rights reserved