Investigation of Lithium Thionyl Chloride Battery Safety Hazards
Final technical rept. Sep 1981-Nov 1982
GTE COMMUNICATIONS PRODUCTS CORP WALTHAM MA POWER SYSTEMS OPERATION
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The chemistry of discharge and overdischarge in LiSOCl2 cells has been examined with Raman emission, Fourier transform infrared, and electron spin resonance spectroscopies to determine if any hazardous reactions can occur. Under moderate discharge rate at room temperature, the electrolyte from discharged and cathode limited overdischarged cells contains primarily LiAlCl4.3 SO2, LiAlCl.2 SOCl2, and perhaps LiAlCl4.SOCl2.SO2 traces of SO3 are indicated. Three free radicals are present at low concentrations on discharge and cathode limited overdischarge with two additional radicals appearing on extended anode limited overdischarge. At least one of these is cationic polymeric sulfur. Both FTIR and ESR suggest intermediates exist with lifetimes on the order of days from discharge and overcharge. No hazardous reactions were observed at anytime. Pressure from SO2, a principal result of discharge, remains low due to the LiAlCl4.3 SO2, complex in solution. Scanning electron and optical microscopic investigations lithium dendrite structure. Individual dendrites do not grow any longer than about 50 microns or any thicker that about four microns in diameter before branching at random angles. The extent of dendritic growth and the fate of the dentrites depends on the discharge conditions. No overcharged hazards were encountered in this study though several hazard scenarios suggested themselves.
- Electric Power Production and Distribution
- Safety Engineering
- Atomic and Molecular Physics and Spectroscopy