The Vrije Universiteit Brussel explains us some of the keys about battery thermal management and how the consortium is working in this field to achieve the he objective of developing a reduced-order battery thermal model.
Read on to learn more about it!
Battery thermal management is critical in achieving performance and extended life of batteries in electric vehicles under real driving conditions. Why is so important?
The optimal temperature for Li-ion cells covers a range of 15°C to 35°C. Due to the limited temperature tolerance of components and relatively unstable chemistries, the excessive high and low temperature can both reduce the life and threaten the safety of the battery, even cause permanent damage. It could be even worse when hundreds of cells are connected in series or in parallel. A long-term existence of large temperature difference will derogate consistency of cells in a battery module. Conversely, poor consistency will lead to varied heating effects in cells that enlarge the temperature difference further to form a vicious circle. Moreover, the inconsistency will directly degrade the overall performance of the battery pack. Therefore, in order to prolong the cycle life and maximize the capability of Li cells an efficient battery thermal management system (BTMS) is required to maintain the proper temperature range and to minimize the temperature gradient of these batteries to prevent adverse effects from temperature and to achieve long cycle life.
What is the main challenge to developing a reduced-order battery thermal model?
In order to keep the cell temperature in the safe temperature range, there is a need of a thermal model to predict the cell temperature distribution over the surface of the battery and maintain an equal heat distribution.
For the modelling and simulation of batteries and the development of the reduced model-based BMS, the most important challenge is to select and build a suitable battery model that will get a fair compromise in the balance of complexity and accuracy of the battery. For example, an electrochemical model shows a clear relationship between the electrochemical parameters and battery geometry but require a large number of numerical equations which increases the complexity of the system. On the other hand, among different battery models, electrical models are more realistic, intuitive, useful and easy to handle. In the end, the compromise between accuracy and complexity is the main challenge in developing a reduced-order thermal model.
How is the UPSCALE project going to predict the thermal behaviour of battery systems?
In the framework of UPSCALE and in particular in WP1 VUB’s role is to develop a 1D thermal model based on a dedicated lithium-ion battery type and chemistry that can predict the thermal behaviour of the battery cell. The model will be used for the aerodynamic CFD simulations (ACFDSs) and will help in determining the accurate air-cooling power required to keep the battery system configuration in an optimal temperature range. For that, as a battery research-oriented centre, VUB will develop a simplified 1D model of the battery that will be used for the ACFDS. The model will be based on the semi-empirical approach in a MATLAB/Simulink® interface. The goal of the model is to reproduce the cell’s electrical and thermal performances with two parts: the electrical and thermal parts.