Oxygen reduction in fuel cell electrolytes
Voltage losses in the O{sub 2} cathode represent the major inefficiency in aqueous fuel cells for transportation or stationary applications. Experimental and theoretical studies of oxygen reduction (OR) in novel acid and alkaline electrolytes on smooth and supported Pt have been carried out. Similar kinetically limited rates for OR were measured in the super-acid electrolytes trifluoromethane sulfonic acid (TFMSA) and tetrafluoroethane-1,2-disulfonic acid (TFEDSA), with the rotating disk electrode (RDE) technique at 23 C and pH = 1. The mechanism for OR on Pt in alkaline electrolytes is complicated by the concurrent oxidation and reduction of Pt. Rotating ring-disk electrode (RRDE) studies carried out with anodic and cathodic potential sweeps in 0.1 to 6.9 M KOH and 0.1 to 4.0 M K{sub 2}CO{sub 3} revealed similar currents when corrected for O{sub 2} solubility differences. Porous gas diffusion electrodes (GDE) with supported Pt catalyst were studied in a special cell with low uncompensated solution resistance. Cyclic voltammograms yielded measurements of the wetted areas of carbon and Pt and the local electrolyte composition. Models for the steady-state operation of porous GDE's were developed. These models account for the diffusion and reaction of O{sub 2} and ionic transport in KOH and K{sub 2}CO{sub 3}. The results suggest that modifications of the GDE structure will be necessary to obtain good performance with aqueous carbonate electrolytes.
- Research Organization:
- California Univ., Berkeley, CA (USA)
- OSTI ID:
- 5616925
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
300505* -- Fuel Cells-- Electrochemistry
Mass Transfer & Thermodynamics
ACID ELECTROLYTE FUEL CELLS
ALKALI METAL COMPOUNDS
ALKALINE ELECTROLYTE FUEL CELLS
CARBON COMPOUNDS
CARBONATES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CONSTRAINTS
DIFFUSION
DIRECT ENERGY CONVERTERS
EFFICIENCY
ELECTROCHEMICAL CELLS
ELECTRODES
ELEMENTS
FUEL CELLS
HYDROGEN COMPOUNDS
HYDROXIDES
KINETICS
MATHEMATICAL MODELS
METALS
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDATION
OXYGEN
OXYGEN COMPOUNDS
PERFORMANCE
PLATINUM
PLATINUM METALS
POTASSIUM CARBONATES
POTASSIUM COMPOUNDS
POTASSIUM HYDROXIDES
REACTION KINETICS
REDUCTION
SULFONIC ACIDS
TRANSITION ELEMENTS
VOLTAGE DROP
VOLTAMETRY