The effect of very low current discharge is quite different. Studies showed that discharges at rates less that 0.1 mA/cm2 increase the rate of self discharge due to disturbance of the passivation layer. The following diagram illustrates that at discharge rates of approximately 0.002 mA/cm2, and a temperature of 37°C, the Li/SOCl2 cells will lose 15% of their capacity due to self discharge.
At elevated temperatures, the rate of self-discharge increases dramatically resulting in a significant loss of cell capacity during storage and discharge. This is because the rate of passivation layer growth increases as a function of temperature. As in the case illustrated above, the effect of self-discharge at elevated temperatures is most prevalent during low current discharges. During a low current discharge ( < 0.1 mA/cm2) at elevated temperatures, the self-discharge rates actually become larger that the rate of discharge.
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