Discharge Reaction Mechanisms in Li / SOCl2 Cells

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Abstract
The processes taking place during the discharge of cells were studied. Test vehicles included wound D, bobbin configuration 2D cells, and 2000 A‐hr prismatic cells. Dried cathodes taken from 2D cells, discharged at 150 mA were analyzed quantitatively for lithium‐sulfur oxyacid salts. Little or no such salt was found for cells discharged at ambient temperature. Measurements of the open‐circuit voltage of this system as a function of temperature showed essentially linear dependence with positive slope between +72° and −20°C, but the voltage fell more steeply as the temperature approached −60°C. Appearance of a nonvolatile reducing species occurred in the cathodes of cells discharged at −20°C, which were not present in cathodes from cells discharged at higher temperature. Controlled potential electrolysis of supporting electrolytes containing limited amounts of were carried out between 0° and 25°C. The electrical equivalent of thionyl chloride was found to be between 1.5 and 2.0 F/mole. The 2000 A‐hr cells were used to measure dissolved and escaping at atmospheric pressure and ambient temperature from anode‐limited and cathode‐limited cells. The amount of produced was found to be only a fraction of that predicted by until near the end of discharge. The total amount of produced by the end of discharge was not more than predicted by this reaction. Vented, anode‐limited cells did not release while cathode‐limited cells did. Temperature cycling of electrolyte taken from cells immediately after discharge was carried out in a sealed vessel. Pressure hysteresis occurred, which could not be duplicated with simulated used electrolyte made with S, , , , and cathode material. At −20°C and below, the discharge reaction may be significant, while at temperatures higher than this, the reaction may predominate, where the remains in solution. Slow decomposition according to may subsequently take place.

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