New Electrolyte Salts for Li / SOCl2 Cells

The high energy density electrochemical system Li/SOCl/sub 2/ has inherently good volumetric energy density and current capability. The currently used electrolytes of LiAlCl/sub 4/ and Li/sub 2/B/sub 10/Cl/sub 10/ possess objectionable features, and therefore new electrolyte salts were evaluated. Two promising electrolytes were discovered, LiGaCl/sub 4/ and Li/sub 2/O X 2GaCl/sub 3/. In SOCl/sub 2/, both salts had solubilities and conductivities similar to LiAlCl/sub 4/ at temperatures down to -30/sup 0/C. Both electrolytes were evaluated in spirally wound D cells. At currents of 1A (approximately C/12) or below, the voltages and capacities were closely comparable to those recorded for LiAlCl/sub 4/. At higher currents of 3 or 4A, the gallium-based electrolytes delivered capacities as much as 60% greater than LiAlCl/sub 4/. This dramatic increase in high current capacity probably is due to reduced cathode passivation. Suggestions are made as to the cause of the increase in capacity.