Volvo Cars is going all in on electrification with one of the most ambitious targets of all legacy car manufacturers; to phase out internal combustion and become fully electric by 2030. This mindset has enabled the re-direction of research and development towards focusing on fully electric vehicle (EV) platforms.
The shift towards EVs comes with many advantages and opportunities especially when vehicles can be designed from the ground up as EVs instead of being stuck between conflicting requirements that often is the case for mixed propulsion platforms. The main component of any EV today is the energy storage. In terms of both mass and cost it is a significant part of the vehicle. By far the most dominating type of energy storage for current generation EVs are Li-Ion battery cells. Li-Ion batteries with their high energy density, performance and durability are at the moment the most suitable choice for energy storage in the premium car segment.
With all their benefits Li-Ion batteries also introduce an array of new requirements and loading scenarios into the vehicle design process. One of these new types of loading scenarios that needs to be considered are the swelling forces from the cells on the vehicle structure. The loading from cell swelling is a symbiotic relationship between the battery cells and the battery structure. The battery cells require a certain pre-compression and surrounding stiffness in order to maximize the durability. Moreover, the battery structure needs to be dimensioned correctly for the used cell in order to ensure vehicle durability and safety. This problem becomes even more complex when taking into account that different cell types and cell chemistries have different requirements and heavily affects the loading on the structure.
This poster aims to show how Volvo Cars is working with advanced Finite Element models in parallel with physical testing in order to build up state-of-the-art CAE swelling models. One of the main challenges with building virtual swelling models is the immaturity of the technology. Compared to internal combustion vehicles, EVs still only make up a small portion of the vehicle fleet and most of the EVs on the roads are still very young in comparison. This means that component testing and accelerated aging is necessary in order to build up adequate knowledge to verify the models. Physical testing is expensive, time consuming and requires physical parts that are often not available until the later stages of the project development cycle. It is therefore crucial to understand the mechanisms on both micro and macro scale to be able to create models that can adequately predict swelling behavior when only initial cell design and chemistry of the cell are available.