What is at issue?
AVL List GmbH focuses, among other things, on developing and testing lithium-ion batteries, as used in electric cars, for example. This requires an in-depth knowledge of how various components and in particular individual cells have to be integrated and interconnected in order to achieve the required level of performance, safety and durability in the end. AVL’s customers such as car manufacturers are interested in obtaining information about battery life and the latest developments in the battery sector.
The research question: Mechanical stress and its impact on battery life
Factors such as temperature, structural changes during charging and discharging and the time of recharge all have an impact on the ageing process of the battery and are taken into account in battery design. Until now, it was not known whether mechanical stress on a vehicle (such as vibration or shock) contributes to the battery’s cell ageing process and this aspect had been neglected when estimating battery life. It does indeed seem plausible that strong mechanical forces could have a negative influence on the cells and their chemical processes by triggering particle cracking, i.e. a break-up of the active material particles.
AVL therefore investigated whether mechanical stress has an impact on the lifespan of a battery cell and thus should be taken into account when calculating the expected battery life.
Cooperation in the CD Laboratory
A battery consists of cells which are interconnected to form modules and large battery packs with the aim to deliver the desired levels of energy and power as well as to provide optimal safety and robustness. AVL has the expertise it takes to properly integrate cells into modules and battery packs and also has in-depth knowledge of cell chemistry. The basic scientific research into electrochemistry, which is just as important to development, is however carried out in collaboration with external partners. The CD Laboratory headed by Univ.Prof. Dr. Martin Wilkening offers the required depth of university-based research and broad-based technical expertise, including numerous analytical methods and large-scale equipment.
Results: More knowledge avoids detours
Numerous experimental setups were developed and implemented at the CD Laboratory. The result of the application-oriented basic research was clear after four to five years: for certain material classes and components, mechanical stress does not influence the durability of a lithium-ion battery cell to the extent originally anticipated. This knowledge saves time and money in battery development and validation.
Results: The future radar
Once it had been clarified whether mechanical stress influences the lifespan of a battery cell, the CD Laboratory turned its attention to a new topic which is also of crucial significance to the company: the solid-state battery cell as the technology of the future. AVL needs to understand this cell technology in detail in order to be able to develop innovative batteries for the markets of the future. The CD Laboratory certainly lived up to its radar role: through this research cooperation, the company has a good insight into the key topics addressed by international top research and gains specific expertise in the technologies of the future, thereby securing a critical head start in battery development. When the latest cells are launched onto the market, AVL will be excellently positioned from the outset and will have a competitive advantage. The result is therefore a solid knowledge base for future work.