Study on Water Management of Polymer Electrolyte Fuel Cell (2nd Report, Operation of PEMFC in Wide Range of Current Density under Low-humidification Condition)

Abstract

Until now, perfluorinated proton exchange membrane (PEM) has been widely used as the electrolyte for PEMFC. As long as the perfluorinated PEM is used for the electrolyte, both the cell performance and durability of PEMFC strongly depends on the water content in its electrolyte, since the high conductivity of electrolyte is presented only at the sufficient hydrated state. On the other hand, pre-humidification of fuel and oxidant gases complicates the PEMFC system and prevents it from cost reduction. Therefore, in order to achieve simultaneously the high performance, durability and cost reduction of PEMFC, it is though to be a best way that both the anode and cathode catalyst layers will be highly humidified only by the water produced through an electrode reaction without pre-humidification of fuel and oxidant gases. Although the management of the vapor permeation rates through gas diffusion layers will be most effective for such a self-humidified PEMFC, it isn't so easy to achieve it in the wide range of current density. In this study, by using the cell simulation method for PEMFC, we calculated numerically the vapor permeation rates through anode and cathode gas diffusion layers which enabled the self-humidified PEMFC without pre-humidification or with low pre-humidification of fuel and oxidant gases.