With the increasing relevance of electric vehicles and LEVs, the question of the environmental impact of these vehicles is also becoming more and more important. "The service life of the battery cells used is limited, as the usage requirements can no longer be met at some point. However, for an application with lower requirements, aged batteries can still be used in a second life," explains Prof Dr Stefan Bracke from the Chair of Reliability Engineering and Risk Analysis, who is leading the research project. However, in order to enable such continued use in a so-called second life, it is necessary to record, assess and quantify the ageing due to the gradual reduction in the capacity of a battery. "In this way, conclusions can be drawn about the performance of the battery and safety-relevant aspects," says Bracke.

As part of the research project "Re-use of battery cells: CT analysis of lithium-ion batteries to assess function- and safety-critical features for the second life phase (RELIBRE)", research is now being carried out into how computed tomography can be used to analyse correlations between the use and ageing of battery cells.

Analysing the ageing of battery cells with computed tomography

"Computed tomography makes it possible to analyse the inside of battery cells using images without having to open the battery. This allows various changes inside the battery cell that have an influence on ageing to be visualised non-destructively. This allows a more precise examination of the ageing condition of the battery, which means that the second-life capability of a battery can be better assessed and the selection of an application scenario can be optimised," Professor Bracke continues.

A particular focus of the project is on the interactions between the use of the batteries in the first life cycle and the observable changes through production and use. Statistical methods will be used to analyse correlations in order to draw conclusions about the ageing processes and their causes.