No abstract

No abstract

A molten carbonate fuel cell cathode model was developed which enables the estimation of performance as a function of cathode electrolyte content. This model is neither a thin film nor a conventional agglomerate model, but involves the calculation of the effective agglomerate diameter, porosity, tortuosity, and number based on knowledge of the electrode's pore spectrum and electrolyte content. Calculated electrode performance and experimental results are compared for cathodes of different pore spectra over a range of electrolyte contents.

Polarization data were obtained for the reduction of oxygen on porous lithiated nickel oxide fuel cell cathodes in lithium-potassium carbonate electrolyte at 650~ Cathode thickness was varied from 0.013 to 0.112 cm with the maximum performance occurring for cathodes of approximately 0.06 cm thickness. The polarization data were optimized for each electrode by varying the electrode electrolyte content in a half-cell apparatus. The optimum content occurred when the combination of internal ionic resistive, diffusional, and activation losses resulted in minimum overvoltage.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 142.58.129.109 Downloaded on 2015-03-16 to IP

Limiting currents obtained with rotating gold wire cathodes indicate that oxygen dissolves in Li, K carbonate melt predominantly as superoxide. The reduction of dissolved oxygen proceeds at polarizations only moderately larger than the diffusion overvoltage for the complete reduction of superoxide. The remaining polarization can be rationalized as mostly zomc concentration overvoltage. In some experiments, a second wave is observed which appears to be due to some cathodic process which does not involve oxygen.A summary of previous work on the reduction of oxygen in molten carbonates has been given by Appleby and Nicholson (1). The same workers also studied the reaction in Li2COa on gold (1) and in the * Electrochemical Society Active Member.ternary Li, Na, K eutectie on gold and on silver (2, 3). Silver is a rather special case, presumably because of the large solubility of oxygen in this metal. The essential findings were that dissolved molecular O~ can be neglected as primary (diffusing) species. The cath.