Abstract Air-breathing PEMFCs consist of an open cathodic side to allow an entirely passive supply of oxygen by diffusion. Furthermore, a large fraction of the produced water is removed by evaporation from the open cathode. Gas diffusion layers (GDLs) and the opening size of the cathode have a crucial influence on the performance of an air-breathing PEMFC. In order to assure an unobstructed supply of oxygen the water has to be removed efficiently and condensation in the GDL has to be avoided. On the other hand good humidification of the membrane has to be achieved to obtain high protonic conductivity. In this paper the influence of varying cathodic opening sizes (33%, 50% and 80% opening ratios) and of GDLs with different wetting properties are analysed. GDLs with hydrophobic and hydrophilic properties are prepared by coating of untreated GDLs (Toray ® carbon paper TGP-H-120, thickness of 350 μm). The air-breathing PEMFC test samples are realised using printed circuit board (PCB) technology. The cell samples were characterised over the entire potential range (0–0.95 V) by extensive measurements of the current density, the temperature and the cell impedance at 1 kHz. Additionally, measurements of the water balance were carried out at distinct operation points. The best cell performance was achieved with the largest opening ratio (80%) and an untreated GDL. At the maximum power point, this cell sample achieved a power density of 100 mW cm −2 at a moderate cell temperature of 43 °C. Furthermore, it could be shown that GDLs with hydrophilic or intense hydrophobic properties do not improve the performance of an air-breathing PEMFC. Based on the extensive characterisations, two design rules for air-breathing PEMFCs could be formulated. Firstly, it is crucial to maximise the cathode opening as far as an appropriate compression pressure of the cell assembly and therewith low contact resistance can be assured. Secondly, it is advantageous to use an untreated, slightly hydrophobic GDL.
[1]
Christopher Hebling,et al.
Fuel Cells for Low Power Applications
,
2002
.
[2]
Andreas Schmitz,et al.
Planar self-breathing fuel cells
,
2003
.
[3]
G. Squadrito,et al.
Effects of the Diffusion Layer Characteristics on the Performance of Polymer Electrolyte Fuel Cell Electrodes
,
2001
.
[4]
Drew Myers,et al.
Surfaces, interfaces, and colloids
,
1991
.
[5]
Suk Won Cha,et al.
Development of portable fuel cell arrays with printed-circuit technology
,
2003
.
[6]
T. Springer,et al.
Water Uptake by and Transport Through Nafion® 117 Membranes
,
1993
.
[7]
K. Oguro,et al.
Simulation of a polymer electrolyte fuel cell electrode
,
1997
.
[8]
Hubert A. Gasteiger,et al.
Handbook of fuel cells : fundamentals technology and applications
,
2003
.
[9]
E. Passalacqua,et al.
Influence of the PTFE content in the diffusion layer of low-Pt loading electrodes for polymer electrolyte fuel cells
,
1998
.
[10]
Christopher K. Dyer.
Fuel cells for portable applications
,
2002
.
[11]
Shimshon Gottesfeld,et al.
Low platinum loading electrodes for polymer electrolyte fuel cells fabricated using thermoplastic ionomers
,
1995
.
[12]
Edson A. Ticianelli,et al.
Development and electrochemical studies of gas diffusion electrodes for polymer electrolyte fuel cells
,
1996
.