Accession Number : AD0448933

Title :   ELECTROCHEMISTRY OF FUEL CELL ELECTRODES,

Corporate Author : TYCO LABS INC WALTHAM MA

Personal Author(s) : Butler, James N. ; Meehan, Mary L. ; Makrides, A. C.

Report Date : SEP 1964

Pagination or Media Count : 1

Abstract : The double-layer capacity of indium amalgams was measured at 25 C in 0.1 M HClO4 using a dropping electrode. Fourteen amalgams ranging in composition from 0.001 mole % to 64.4 mole % In were studied. At concentrations of indium below 0.001%, the capacity is identical to pure mercury; at higher concentrations, a pseudocapacity due to the dissolution of indium is observed at potentials more positive than the In-In+3 equilibrium potential. As the concentration of indium varies from 1% to 70%, the zero-charge potential shifts 0.4 volts more negative, and the capacity-potential curve shows a corresponding shift. The capacity-surface charge curve shows the same ''hump'' near the zero charge point in concentrated indium amalgams as in pure mercury. At a surface charge of - 10 micro coul/sq. cm, the capacity varied from 15 micro f/sq. cm for mercury to 20 micro f/sq. cm for 64% indium amalgam. At a surface charge of + 10 micro coul/sq. cm, the capacity of a 64% indium amalgam was approximately twice that of mercury. The contribution to the capacity from the diffuse double layer was calculated using the Gouy-Chapman theory. The influence of the diffuse double layer is much greater for concentrated amalgams than for mercury. Previous data for hydrogen overvoltage on indium amalgams was used together with the capacity measurements to analyze the effect of the diffuse double layer on the hydrogen discharge reaction. (Author)

Descriptors :   (*FUEL CELLS, ELECTRODES), (*ELECTRIC DOUBLE LAYER, INDIUM ALLOYS), MERCURY ALLOYS, ELECTROLYTES, PERCHLORIC ACID, HYDROGEN, VOLTAGE, ELECTRIC DISCHARGES, STATIC ELECTRICITY, POLARIZATION.

Distribution Statement : APPROVED FOR PUBLIC RELEASE