Vibrational Analysis of Lithium-Ion Batteries

Lithium-Ion Secondary Batteries are among the key technologies for electric vehicles. During operation, they face strong structural changes of their electrodes. This phenomenon will become even stronger when implementing high-energy materials. Knowing the state of the changes can help to exploit the potentials of this technology and to increase both safety and lifespan. Currently, the changes are monitored with costly pre-application diagnostics; within the application, the data needs to be approximated with the electrical two- pole behavior of the battery and thus data about the real changes is scarce. This is where „VALERIE - Vibrationsanalyse von Lithium-Ionen Batterien (Vibration Analysis of Lithium Ion Batteries)“ comes in. It aims check the capabilities of the in other areas wellestablished technology of modal analysis, to address the problems found in Lithium-Ion batteries. For this method the cell is excited with a mechanical signal and the response to it is measured. From this response properties of the system can be derived In previous work with expensive equipment and optimized conditions, first promising results have been achieved. The proof of concept especially in terms of reproducibility and usable measurements under real conditions is yet to deliver. In this exploratory project, influences of the surrounding, position of the sensors, frequencies with their respective gain in information, and others have to be checked. This is done by a combined approach of measurement in a close to real environment with Finite Element Modelling. The validation of the method is done by Dilatometer measurements. The goal is to check for the suitability of the approach to deliver relevant data for the Battery Management System and in second line also as cost efficient alternative to current analysis throughout development of a battery. A success of the project would mean a raise of the TRL from 2-3 to 4 with special focus on the application. A side goal is to promote the method to relevant industry and to prepare a follow up project. Also a possible failing of the method will be communicated. A successful project would help to improve the diagnostics of Lithium-Ion batteries also within the application and to further improve the overall system.