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Pohang, South Korea

Kong I.M.,Seoul National University | Choi J.W.,Korea Institute of Energy Research | Kim S.I.,Korea Atomic Energy Research Institute | Lee E.S.,JNTG and 235 36 Mannyun ro | Kim M.S.,Seoul National University
Applied Energy | Year: 2015

Adequate hydration of the membrane is required to ensure high proton conductivity in proton exchange membrane fuel cells (PEMFCs), which, in turn, is required for achieving high cell performances. While external humidifiers are typically used to humidify the supplied air in conventional systems, their use increases the complexity, weight, volume, and parasitic power loss in fuel cell systems, rendering them unviable in some systems, particularly for portable applications. In this study, the structure of a gas diffusion backing layer (GDBL) was modified to enhance the self-humidification effect in PEMFCs. Three types of GDLs were prepared for the experiments: a conventional GDL (GDL-A with uniform single GDBL) and two modified GDLs (GDL-A'B with uniform double GDBL and GDL-A'C with heterogeneous double GDBLs). In order to evaluate the effect of stacking and structural design on the self-humidification characteristics, some characteristics of the GDLs such as contact angle, resistance, and vapor permeation rate were measured. The electrochemical performances of the fuel cells were also measured at various relative humidity (RH) and stoichiometric ratio (SR) conditions. The results showed that stacking had a negligible effect, whereas the structural design of the GDBL had a significant effect on self-humidification. The self-humidification effect and the cell performance were improved significantly in the structurally modified GDBL. In addition, considering the actual field conditions and the results of the present study, it was concluded that the structural modifications made to the GDBL would be beneficial in improving the performance of the self-humidified PEMFCs. © 2015 Elsevier Ltd.

Cho J.,Korea Institute of Energy Research | Park J.,Seoul National University | Oh H.,Seoul National University | Min K.,Seoul National University | And 2 more authors.
Applied Energy | Year: 2013

The optimal design of the gas diffusion layer (GDL) of proton exchange membrane fuel cells is crucial because it directly determines the mass transport mechanism of the reactants and products. In this study, the micro-porous layer (MPL) penetration thickness, which affects the pore size profile through the GDL, is varied as the design parameter of the GDL. The cell performance is investigated under various humidity conditions, and the water permeability characteristics are studied. In addition, the accelerated carbon corrosion stress test is conducted to determine the effect of MPL penetration on GDL degradation. GDLs with large MPL penetration thickness show better performance in the high-current-density region due to the enhanced management of water resulting from a balanced capillary pressure gradient. However, the loss of penetrated MPL parts is observed due to the low binding force between the MPL and the GDL substrate. © 2013 Elsevier Ltd.

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