Analysis of a lithium/thionyl chloride battery under moderate-rate discharge

A one-dimensional mathematical model of a spirally wound lithium/thionyl ch loride primary battery is developed and used for parameter estimation and d esign studies. The model formulation is based on the fundamental conservati on laws using porous electrode theory and concentrated solution theory. The model is used to estimate the transference number, the diffusion coefficie nt. and the kinetic parameters for the reactions at the anode and the catho de as a function of temperature. These parameters are obtained by fitting t he simulated capacity and average cell voltage to experimental data over a wide range of temperatures (-55 to 49 degrees C) and discharge loads (10-25 0 Ohm). The experiments were performed on D-sized, cathode-limited, spirall y wound lithium/thionyl chloride cells. The model is also used to study the effect of cathode thickness on the cell capacity as a function of temperat ure, and it was found that the optimum thickness for the cathode-limited de sign is temperature and load dependent. (C) 1999 The Electrochemical Societ y. S0013-4651(98)07-107-9. All rights reserved.