Membrane Electrode Assembly health detection in a 4 cells stack using linear sweep voltammetery

Fuel cell technology has undergone significant development in the past 15 years, spurred in part by its unique energy conversion characteristics; directly converting chemical energy to electricalenergy. Of the six different fuel cell types pursued commercially, the proton exchange membrane fuel cell (PEMFC) has received the greatest amount of research and development investment due to its suitability in a variety of applications. PEMFC electrolyte permeability to reactants andelectrons is considered as a critical factor which reduces FC performances and lifetime (1). Linear sweep voltammetery (LSV) is a powerful tool allowing the estimation of hydrogen crossover and the detection of any internal electronic short between anode and cathode. A scanrate between 1 and 4mVs−1 is adopted. In order to prevent platinum oxidation, the scan potentialrange is limited from 0 to 0.8V [2]. In LSV experiments, the anode is usually fed with hydrogenwhile the cathode is supplied with nitrogen. At this value all crossover H2 is instantaneously oxidized due to the high overpotential applied. Based on the limiting current, one can, ultimately, calculate the flux of H2 gas (Jxover) using Faraday’s law (2). Where ilim (Acm−2) is the transport limiting current density; n is the number of electrons required per reaction (HOR = 2), and F is the Faraday’s constant (96,485 Cmole−1). The purpose of this test is to verify the device (Biologic sp150) performance (when it working with fuel cell 4 cells stack) and the MEAs health assessment within the stack. As shown in Fig.1,the working electrode should connect to cathode and reference and counter electrode should connect to anode of single cell. Fig.1 (b) shows single cells and stack LSV. To verify the deviceperformance, linear sweep voltammograms of single cells and stack at different temperatures andpressures were recorded (Fig 2 a,b) and compared with values in the literature (3). As shown in Fig 2 (c,d) the demeanor of single cells and stack are similar to literature and illustrate the verification of potentiostate/galvanostate in LSV test. To assess the MEAs health, the amount of hydrogen (mL/min-cm2) was calculated using equ.1 and compared with the DOE limit values (3)

کلیدواژه ها:

Polymer electrolyte membrane fuel cell ، 4 cells stack ، Hydrogen crossover ، Linear sweep voltammetry