Assessment of Capacity Loss in Low-Rate Lithium/Bromine Chloride in Thionyl Chloride Cells by Microcalorimetry and Long-Term Discharge

Real-time discharge is one of the few reliable methods available for determining capacities of low-rate cells. The utilization of high energy density lithium batteries in low-rate implantable applications has increased the need for more timeefficient methods of predicting cell longevity since cells have been shown to last in excess of eight years. The relationship between heat dissipation and self-discharge of low-rate lithium/BCX (bromine chloride in thionyl chloride) cells was studied and allows prediction of cell life prior to the availability of real-time data. The method was verified by real-time cell discharge data and provided estimates of delivered capacity within 6% of the actual values.