The technology of the Li/BrCl in SOCl2 inorganic battery system: performance and self-discharge characteristics following long-term storage

Abstract

Investigations were conducted on Li/BrCl in SOCl2 cells to determine both the performance and shelf life characteristics after storage for a period of one year at various temperatures. Room temperature discharge test results indicate that there is little self-discharge in those cells stored at either room temperature or at −40° C. Even when the cells were subjected to elevated storage temperatures, the discharge results show that the cells exhibit a low self-discharge rate. However, cells stored at an elevated temperature do exhibit a decreased rate capability when compared to those results obtained from fresh cells. From the 56 ohm load discharge performance results, the self-discharge rate for cells stored at −40, 24, 50 and 72° C was calculated. Further, the activation energy over the temperature range was found to be 27.6±1.7 kJ. Also, the self-discharge rate was monitored under light load conditions. The results for Li/BrCl in SOCl2 D cells discharged under a current density of 2.38 to 0.016 mA cm−2, show that the operationally induced self-discharge rate reaches a maximum of 4.5μA cm−2 for cells discharged under a current density of 0.034 mA cm−2 and decreases to 2.9μA cm−2 as the discharge current density decreases to 0.016 mA cm−2. These data indicate that the self-discharge rate for cells discharged under very light loads may eventually approach that for cells stored under open circuit conditions.