Mass transport phenomena in proton exchange membrane fuel cells using O[sub 2]/He, O[sub 2]/Ar, and O[sub 2]/N[sub 2] mixtures; 1: Experimental analysis

• Published in: Journal of the Electrochemical Society Vol. 141:8
• Main Authors: Rho, Y.W., Velev, O.A., Srinivasan, S., Kho, Y.T.
• Format: Journal Article
• Language: English
• Published: United States 01.08.1994
• Subjects: 30 DIRECT ENERGY CONVERSION; 300505 - Fuel Cells- Electrochemistry, Mass Transfer & Thermodynamics; ARGON; CHEMICAL ACTIVATION; CHEMICAL REACTIONS; CHEMISTRY; CURRENT DENSITY; DATA; DIRECT ENERGY CONVERTERS; ELECTRIC POTENTIAL; ELECTRIC-POWERED VEHICLES; ELECTROCHEMICAL CELLS; ELECTROCHEMISTRY; ELEMENTS; EXPERIMENTAL DATA; FLUIDS; FUEL CELLS; GASES; HELIUM; INFORMATION; ION EXCHANGE MATERIALS; MASS TRANSFER; MATERIALS; NITROGEN; NONMETALS; NUMERICAL DATA; OXYGEN; RARE GASES; REDOX REACTIONS; SOLID ELECTROLYTE FUEL CELLS; VEHICLES
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.2055065

This investigation on proton exchange membrane fuel cells (PEMFCs) consists of two parts: (1) an experimental analysis of the oxygen reduction reaction, using an O[sub 2]/He, O[sub 2]/Ar, or O[sub 2]/N[sub 2] gas mixtures as the cathodic reactant, to determine the effects of oxygen partial pressure, temperature, and pressure on the contributions to activation and mass-transport overpotential; and (2) a theoretical analysis of oxygen reduction to: first, interpret the experimental results with O[sub 2]/He, O[sub 2]/Ar, and O[sub 2]/N[sub 2] gas mixtures as the cathodic reactant, and, second, elucidate the effects of the structure of the electrode and of the physicochemical parameters of the reactant gas, as well as of temperature and pressure, on the oxygen electrode potential vs. current density behavior. For the experimental analysis, which is presented in this Part of the paper, the performance evaluation of PEMFCs (in single cells with the geometric area of the electrodes being 50 cm[sup 2]) was carried out using O[sub 2]/He, O[sub 2]/Ar, and O[sub 2]/N[sub 2] gas mixtures as the cathodic reactants. Experiments were also carried out using air and oxygen. Cell potential vs. current density measurements were made over the temperature range of 50 to 90 C and pressure range of 1 to 5 atm. These studies showed that mass-transfer limitations are less in PEMFCs with O[sub 2]/He, than with O[sub 2]/Ar or O[sub 2]/N[sub 2] gas mixtures. Furthermore, at an oxygen composition greater than 40% of O[sub 2] in the gas mixture, the pseudo-linear region of the potential vs. current density plot is extended at least up to 1 A/cm[sup 2]. With air as the cathodic reactant, mass-transport effects are minimal at pressures of 3 atm and higher. Temperature effects are less significant than pressure effects, because in the former case there is a compensating effect of higher temperature and lower partial pressure of oxygen on the electrode kinetics of oxygen reduction.