Numerical Simulation of Lithium Ion Batteries and Cells

摘要

Lithium ion technology has been available in the automotive industry since about 2005. It is therefore a comparatively new technology in the automotive industry. As a result, there is little to no experience of day-to-day operation in the industry or by customers over the entire life of the vehicle. Added to this is the fact that accidental crash situations, fires or invading foreign bodies near the high-voltage battery pose new risks. A safety level comparable with ICE-vehicles is required. A lot of requirements and specifications have to be met during the development process. Especially the reactions and effects during a crash caused by accelerations and intrusions are extremely important to understand because of the risks for the drivers and passengers during use and after a maybe re-use after an accident. This poster gives an overview of the state of the art of numerical simulation tools used for lithium ion batteries in general. In addition, the numerical simulation tools for crash and crush will be discussed. A LS-Dyna model of a prismatic cell will be shown. With this model several crash simulations were done (front, side, rear and sledtest with specific pulse). Different states of charge were used for the simulations as well. At first an uncharged simulation model with lower volume and lower contact forces between the cell material and the housing and second a full charged one with higher volume and higher contact forces were used. The data size for the model is of about 600 MB - appr. 45000 knots and 38000 elements with an element size of appr. 2 mm. The calculation time is of about 45 minutes by using 8 cores. In result the movement and the reactions of the cell material caused by the acceleration will be shown depending on the crash scenario. Furthermore, forces inside the cell and acceleration datas will be mentioned. Finally, the impact of a re-use after a vehicle crash will be discussed; this depends on the acceleration and the mechanical intrusion. The simulation give some information about the reactions inside of a cell and is helpful to understand the risks better. Out of that technical solutions for a safe re-use can be designed and developed.