Real-time nondestructive evaluation of electrode weld stacks using a laser vibrometer and shock tube

Multi-layered electrode foil-to-tab welds in lithium-ion batteries must provide a strong structural bond as well as electrical connection. These welds can be created by ultrasonic welding, laser welding, or by a combination of the two. In this paper, the applicability of a nondestructive evaluation (NDE) method to evaluate the quality of the multi-layered electrode foils-to-tab welds is studied. The NDE method consists of exciting the electrode foils using an impulse pressure from a shock tube and measuring their resonance using a laser vibrometer. A key advantage of the technique is that it is non-contact and could be applied in real-time in a manufacturing environment. Pearson correlation coefficients are employed to evaluate the similarity between frequency spectra across different specimens of varying weld quality. Presented early results show that the NDE technique is repeatable and can be used to rank the quality of samples, and guide future research in developing a quantitative relationship between Pearson correlation coefficients and electrode weld quality.Published by Elsevier Ltd on behalf of Society of Manufacturing Engineers (SME).