Battery Thermal Management Simulation – 1D+1D Electrochemical Battery and 3D Module Modeling on Vehicle System Level 2021-01-0757
Global concerns on sustainable energy use call for innovative energy conversion technologies. Batteries are key enablers for more sustainable mobility provided the availability of renewable energy sources. Batteries are integrated in battery electric, plug-in hybrid and hybrid electric vehicles. All these applications call for high energy and power density, long lifetime and highest safety. However, there are application-specific objectives like different load profiles and thus specific durability and safety criteria. A single design of a battery cell cannot optimally comply with all envisaged application areas. Tailoring battery designs to a specific application with the aim of approaching engineering limits represents a significant challenge.
Virtual prototyping with predictive models is one key enabler to frontload the development process. This is important in the light of the outlined challenges, which cover a broad range of spatial and temporal scales. The key performance indicators of battery systems depend on design parameters such as basic material properties, electrode, cell, module and pack geometries including its electric and thermal operating conditions.
This work presents a modeling approach to support virtual prototyping on the vehicle level considering thermal aspects of battery modules and electrochemical phenomena of Li-ion batteries. The model comprises three scales. The first scale describes a single battery unit cell in a 1D+1D approach considering transport between the electrodes, intercalation of lithium and degradation phenomena. These mechanisms depend on temperature and in return influence heat generation. The second scale describes the thermal behavior of a battery module in 3D and the third scale models the vehicle performance on a system level. The vehicle level with its multi-physical characteristics also serves as integration layer combining the electrochemical cell and thermal module model. The vehicle levels offers a flexible configuration of multidomain layouts which, combination with tailored domain-optimized solvers, allows for achieving very short computational times.
The model capabilities are demonstrated by simulating the behavior of a battery module on vehicle level. A validated electrochemical model is virtually put into a 3D thermal module model. The thermal model is validated with the help of analytical references and its numerical sensitivity is assessed by dedicated grid variations. A comparison to results from 3D CFD simulations is shown for selected open-loop conditions. The combined multi-scale model is used to investigate the interaction between cell topology, layout of the module cooling and duty cycle. Sensitive areas in the module with respect to Li-plating, SEI decomposition and the onset of thermal runway are identified.
Johann C. Wurzenberger, Mario Jelovic, Mate Šimundić, Igor Mele, Tomaz Katrasnik
AVL LIST GmbH, AVL-AST d.o.o., University of Ljubljana