No abstract

The liquid SO2 solvates of the tetrachloroaluminate of lithium, sodium, calcium, strontium, and their mixtures, have been found to be very highly conductive inorganic electrolytes with low SO2 vapor pressure. The conductivity is as high as 10 -1 t] -1 cm -1 for some compositions. The addition of the SO2 solvate of NaA1C14, Ca(A1C14)2, or Sr(A1C14)s to LiA1C14:3 SO~ has been found to lower the freezing point considerably. The lithium stability at elevated temperatures is best in electrolytes with higher SO2 content such as LiA1C14:6SOs, or SO2 solvate electrolyte containing NaAIC14, than electrolyte containing pure LiA1C14:3SO2.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see ABSTRACTThe chemistry of Li/SOC12 cells containing BrC1, popularly known as BCX cells, has been investigated. BrC1 significantly modifies the chemistry of the Li/SOC12 cell. The discharge of the BrC1 in the cell proceeds through the reductions of C12, Br2, and BrC1. The LiBr formed appears to react with SOC12 to generate sulfur bromides, SO2Br2, Br2, and LiC1. Sulfur halides are also formed in the cell by the reaction of C12, BrC1, or Br2 with S produced by the reduction of SOC12. Addition of BrC1 appears to have an adverse effect on the storability of the Li/SOC12 cell after partial discharge.

The ionic conductivity of polycrystalline lithium iodide containing 0 to 3% (mole) calcium iodide was studied at temperatures between −30° and 130°C.The conductivity increased linearly with the concentration of calcium iodide, and it was concluded that the introduction of calcium ions to the lithium iodide crystals induced Schottky defects. The activation energy for the ionic conduction process of 9.96 normalkcal/normalmole agreed well with the value obtained by other investigators. The electronic conductivity of the calcium doped lithium iodide polycrystals was negligible compared to the ionic conductivity.

The processes taking place during the discharge of Li/SOC12/C 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 oxyaeid 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~ but the voltage fell more steeply as the temperature approached --60~Appearance of a nonvolatile reducing species occurred in the cathodes of cells discharged at --20~ which were not present in cathodes from cells discharged at higher temperature. Controlled potential electrolysis of supporting electrolytes containing limited amounts of SOCI.~ were carried out between 0 ~ and 25~ The electrical equivalent of thionyl chloride was found to be between 1.5 and 2.0 F/mole. The 200,0 A-hr cells were used to measure dissolved SO2 and SO2 escaping at atmospheric pressure and ambient temperature from anode-limited and cathode-limited cells. The amount of SO2 produced was found to be only a fraction of that predicted by 4Li ~-2SOCls -+ S § SO2 + 4LiC1 until near the end of discharge. The total amount of SOs produced by the end of discharge was not more than predicted by this reaction. Vented, anode-limited cells did not release SO2 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, SOs, SOC12, LiA1C14, and cathode material. At --20~ and below, the discharge reaction 8Li + 3SOCls-~ 2S ~-Li2SO8 ~-6LiC1 may be significant, while at temperatures higher than this, the reaction 2nLi + nSOC12-~ 2nLiC1 + (SO), may predominate, where the (SO)n remains in solution. Slow decomposition according to (SO)h-> (n/2)S + (n/2)SOz may subsequently take place.

A rechargeable lithium battery using a cathode of copper(II) chloride and an electrolyte consisting of LiA1C14 9 3SO2 has been developed. The efficiency of lithium plating was evaluated in lithium-limited prototype cells. Cathode rechargeability was evaluated in cathode-limited prototypes, and system energy density was demonstrated by use of a wound D cell. The use of an electrolyte system which reacts reversibly with metallic lithium allowed the use of systematic overcharge to eliminate irreversible loss of lithium from the system and to provide for cell balancing. Lithium cycling figures of merit as high as 190 were attained by use of the overcharging.