A comparison of heat outputs attributed to lithium film formation and repair in Li/SOCl2 and Li/MnO2 cells

Heat output measurements were taken following partial discharges or short circuit tests on Li/SOCl₂ and on Li/MnO₂ cells. The magnitude and change in heat output with time is contrasted using examples from these two basically different systems. The magnitude and duration of the heat output is related to the nature of the film that is undergoing repair and rebuilding on the lithium anode. In the case of Li/SOCl₂, the film forming reaction is the same as the normal discharge reaction, so heat output information can be used to estimate losses in lithium anode capacity attributed to film formation and repair during storage or following intermittent discharges. However, the solvent reaction with lithium is quite different from the normal discharge reaction in lithium cells using solid cathodes and organic solvent based electrolytes. The data show that heat outputs following partial discharge or short circuit are much higher for Li/SOCl₂ than for Li/MnO₂ cells. However, for both of these cell types, formation and repair data are mostly related to the secondary film layer rather than the thin, compact primary layer