Model-based assessment of the operating limits for different battery cells in order to design adaptive fast charging strategies along the entire life cycle
3 years (01.10.2020 - 30.09.2023)
Funding 1.185.553 € (TUBS)
elenia Institute for High Voltage Technology and Power Systems (elenia), TU Braunschweig
Institute of Energy and Process Systems Engineering (InES), TU Braunschweig
Institute for Particle Technology (iPAT), TU Braunschweig
Fast charging of lithium-ion batteries ist one of the key challenges facing electromobility in order to increase customer acceptance. The requirements for fast charging come from the respective application, but are often limited by the material system and cell design. In addition, the cell characteristics deteriorate as the battery ages. Fast charging processes in particular can lead to accelerated aging. Therefore, the operation limits are often designed very pessimistically in order to avoid safety-critical processes and accelerated aging. A promising alternative is the determination of age-dependent operating limits to adjust the fast charging strategy accordingly. However, this approach is associated with challenges, because an age-related adjustment of the operating limits depends on conditions of the material and cell system that cannot be measured directly.
The model-based assessment of the fast charge ability for different materials of lithium-ion-batteries is investigated in "FastChargeLongLife". For this purpose, different novel electro-thermal and physicochemical models are developed and linked together. This enables the determination of the maximum operating limits and optimized fast charging strategies. These fast charging routines will be adaptively adjusted regarding the state of aging in order to prevent critical effects as lithium-plating. After certain cycle counts, some cells will be opened and investigated if critical aging effects occurred due to fast charging. So the models can be verified. The model-based approach enables the fast charging assessment along the complete cycle life of different materials within lithium-ion-batteries. This supports to increase the durability and to decrease the charging time.