Potential of pulsed laser heating for non-destructive quality assessment of bi-layered foils: Demonstration on graphite-copper anodes for use in lithium-ion batteries

The technical performance of films consisting of interconnected layers, such as graphite-copper anodes in lithium-ion energy storage systems, depend on properties of the involved materials determined by the production process. For ensuring high quality of products, non-destructive inline testing methods are required. In this contribution, the assessment of material properties via analysis of the strain/temperature fields triggered by local pulsed laser heating is addressed. For this purpose, numerical simulations are conducted with thermal/mechanical material parameters being linked to surface and morphological properties via multiscale modeling. This approach is applied to graphite-copper anodes, with simulation results being compared to experiments. Parameter studies reveal the influence of morphological features on the temperature and strain fields as well as the effect of ambient conditions and measurement system (e.g., pyrometer, Laser Speckle Photometry, etc.), highlighting the potential of pulsed laser heating in the context of non-destructive quality assessment.