Fast Charging at Cold Conditions—Model-Based Control Enabled by Multi-Scale Multi-Domain Plant Model
2022-01-0857
03/29/2022
- Event
- Content
- Battery electric vehicles (BEV) are a promising technology to provide CO2-free mobility. The enabler for BEVs is a battery that provides maximum driving ranges, short charging times and a long lifetime. Lithium ion batteries (LIB) are an established technology used most likely in many future BEV applications. LIB typically use anodes materials with high share of graphite where inappropriate charging procedures will compromise their lifetime. Under certain conditions, lithium ions deposit as metallic lithium, react with the electrolyte and cause a loss of capacity. The challenge is to derive charging strategies along the physical limits, fast and not yet damaging. This requires a thorough understanding of the electrochemical cause-effect relationships in the battery in interaction with the thermoregulation management at a given charging strategy. Models are a key factor to understand, describe and exploit physics earlier in development phases. Modelling of batteries is important as phenomena taking place on different scales need to be mastered. The intercalation of lithium ions and their participation in parasitic aging reactions happens at the scale of nanometers, the cycling of lithium ions between the electrodes takes place at the scale of micrometers and the thermoregulation applied on module level comprises a scale of centimeters. This work discusses a multi-scale, multi-domain (MSMD) modeling approach to capture the interaction of the battery cell chemistry, thermoregulation and operating strategy. On cell level, the 1D+1D Newman based model is applied and extended with rates to model the deposition of metallic lithium, its resolution into the electrolyte parallel to its passivation. Focus is put on plating approaches presented in literature. The unit-cell model is embedded into a 3D thermal module model. It handles heat sources from the unit-cell model, describes the heat transfer through the solid structure and into the adjoint thermoregulation circuits. Focus is put on a spatial lumping strategy that allows simulating the nano/microscale models on module level with reasonable computational efforts. The model capabilities are demonstrated in validation and comparison simulations. The characteristics of different lithium plating approaches are simulated and discussed with respect to their underlying model assumptions. The plausibility of the 3D thermal model is assessed by convergence investigations in open loop simulation. Here a module geometry inspired by a series production BEV is chosen. The spatial temperature uniformity in the module is compared for different flow patterns of the water circuit connected to the module. The combined MSDM model is applied to simulate fast charging at cold ambient conditions and to derive performance indicators for drive cycle conditions.
- Citation
- Wurzenberger, J., Lechner, C., Jelovic, M., Mele, I. et al., "Fast Charging at Cold Conditions—Model-Based Control Enabled by Multi-Scale Multi-Domain Plant Model," SAE Technical Paper 2022-01-0857, 2022, .