Development of New Electrochemical Method for Measuring Gas Permeability of PEM Fuel Cell Components

Abstract

A Proton Exchange Membrane Fuel Cell (PEMFC) is an electrochemical device that converts directly chemical energy into electrical energy. PEM fuel cells have high efficiency (up to 65%), low working temperatures (between 60‒80 ºC), and produce only water as byproduct [1]. Moreover, these devices are suitable for the replacement of the internal combustion engines with insignificant modifications to the automobile.The PEMFC consists of a membrane with a catalytic layer, also known as membrane electrode assembling (MEA), gas diffusion layer (GDL), bipolar plates (BPs), and auxiliar components likewise sub-gaskets, and sealings used for preventing the gas leakage [1,2]. An essential material property directly influencing the performance and long-life capacity of the PEM fuel cells is the permeability of their components toward gases (H2 and O2).Two classical methods can be used for measuring the H2 permeation of the bipolar plates. First one is based on the differential pressure method where the pressurized H2 is passed through the sample and the time rate of decrease/increase of the pressure on the same/opposite side of the sample is measured. The second method is drawn on introducing H2 maintaining the same pressure on both sides, then the transmitted H2 is measured by a chromatography detector [3].In the present work is proposed a new electrochemical technique for measuring the gas permeability of the BPs. The own-prepared reactor is shown in Fig. 1a. The method is based on covering the sample with a catalytic layer (Fig. 1b) and submerging it in electrolyte. The pressurized H2 is introduced from the bottom of the sample, and the transmitted H2 through it reacts with O2 giving the measured current. Worth noticing that this method is universal and can be used for the analysis of the gas permeation of other semi-conductive and conductive materials not just for FC (e.g., MEAs and GDLs), but other applications.