Requirements for battery ageing model and battery testing RE 94/24

The knowledge of the various aging mechanisms affecting lithium-ion batteries, and their impact on evolution of the life cycle are of high importance to ensure effective operations for cheaper, safer and more efficient batteries. However, degradation phenomena during operation are complex due to lithium-ion batteries modification of active materials, the electrolyte and the electrical collectors inside the cell. Among the most relevant aging causes, in addition to calendar aging, there are cycle aging conditions including current load, depth of discharge (DoD) and state of charge (SoC) window within the battery operates. On top of these operating causes, there are also external causes with a strong influence on the type of degradation of lithium-ion batteries and these are the ambient temperature and possible mechanical stresses. Extreme temperatures in particular accelerates the typical aging phenomena, or triggers new ones if far from the optimal operating conditions (typically 15 - 35 °C). Mechanical stress can be induced accidentally or deriving from the normal compression between the cells in the battery packs, it can influence the type of aging by limiting the free volumetric expansion of the cells (e.g. in the charge-discharge phases). In this report after defining the state of art about aging prediction methods for LIBs it is proposed a design of experiment to be used for the definition of the model (Task 2.4) necessary for the smart BMS to be build and tested in Milestone 3 of DIAMOND project.