Influence of Cathode Gas Diffusion Media Porosity on Open-Cathode Fuel Cells

Abstract

We investigate the effect of gas diffusion media (GDM) porosity on open-cathode fuel cell operation in challenging ambient air conditions known to exacerbate either cell dehydration or liquid water saturation. A less porous cathode GDM improves cell contact that decreases interfacial contact resistances. We relate structural properties of the cathode GDM to heat rejection, oxygen transport, and water management in the open-cathode fuel cell using polarization behavior and electrochemical impedance spectroscopy. Less porous cathode GDM reduce the measured cell temperature at the cathode surface and decrease ohmic resistance by >33% at 0.6 V, increasing current density from 0.197 to 0.299 mA cm −2 . Small decreases in cathode GDM porosity considerably improve thermal management, cell hydration, cathode charge transfer, and decrease ohmic resistance, increasing current density and power production despite concomitant increases in mass transport resistance.

Polymer Electrolyte Fuel Cell Degradation Mechanisms and Their Diagnosis by Frequency Response Analysis Methods: A Review

“…For example, a combination of experiments and simulation was used by several groups to investigate the effect of different flow field geometries in order to reduce the mass transport resistance on the cathode side [49,50]. Others have focused on the understanding of the relationship between the GDL features and resistance to oxygen transport [51], water removal [52], electron conduction, and heat transport [53] using EIS in combination with other experimental techniques. Moreover, the employment of EIS for a better comprehension of the relationship between catalyst layer structure, its efficiency, and durability was extensive and supported the synthesis of MEA with optimised ionomer content, ionomer/carbon ratio, and platinum loading [54][55][56].…”

Effect of the corrugated bipolar plate design on the self‐humidification of a high power density PEMFC stack for UAVs

“…The effective heat conductivity of the porous GDLs is calculated using the parallel paths model for a heterogeneous material consisting of carbon and gas pores, using f-la (16), which ignores convective transport [121].…”

“…The unnumbered arrows show the direction of air flow to achieve a superior performance (such as system-level specific energy 500-800 Wh kg −1 for the operating time of 4 h, vide infra), peripheral systems (such as humidifiers and heaters used in automotive PEMFCs) must be avoided. For this reason, PEMFC systems with a dead-end (occasionally purged to remove water and crossover N 2 ) [9] anode and an open cathode are commonly used in UAV applications [4,5,[10][11][12][13][14][15][16][17]]. An exemplary scheme of such system is shown in Figure 1, wherein dry H 2 is supplied from a high-pressure tank (1) through pressure reducer (2), pressure sensor (3), and fast electromagnetic valve (4) into the anodic compartment (5) of the stack.…”

Influence of Gas Diffusion Media Compression on Open-Cathode Fuel Cells

“…MEA contact resistances are isolated from the HFR using a method described in our prior work. 31 Fuel cell testing.-Cell polarization data and electrochemical impedance spectra (EIS) were collected with an 850e Fuel Cell Test System (Scribner Associates Inc.) with an integrated Frequency Response Analyzer. All polarization and EIS data are the average of 3 MEAs with error bars to show the standard deviation in these MEAs.…”