Investigation on the Self-discharge of the LiFePO4/C nanophosphate battery chemistry at different conditions

Lithium ion batteries with iron phosphate cathodes are gradually improving in their performance and gaining importance, and are more and more considered for new applications. Different aspects of this chemistry were studied in numerous publications; however, very little research was devoted to detailed empirical investigations in order to find out how self-discharge of this chemistry depends on different storing conditions. Precise knowledge about the level of the self-discharge of lithium ion battery cells is very important for improving the performance of the battery management system since it allows also for more precise determination of the actual battery SOC after prolonged storage. In this paper the self-discharge of the nanophosphate LiFePO₄/C is studied at different temperature, SOC conditions and at different SOH levels of the battery. Moreover, cell to cell differences in self-discharge caused by the manufacturing tolerances are investigated.