Thermal Energy Generation of LiAl / FeS Cells

Abstract

Two independent methods were employed to determine the rate of thermal energy generation in 200 A‐hr lithium‐aluminum/iron sulfide cells. The first is an indirect method using thermodynamic calculations based on precise measurements of the cell potential as a function of temperature and state of charge, combined with measurements of the overpotential during discharge. The second is the direct measurement of the cell heat generation using a new high temperature battery calorimeter. The results obtained by these two methods are in excellent agreement. The rate of heat generation is 40–50W per cell during the last 30% of discharge at 100A. Under certain conditions the cell reaction, initially exothermic, becomes endothermic and then exothermic again during discharge. This unusual behavior is caused by the formation of intermediate J‐phase and X‐phase compounds during the course of discharge.