Detection of Anode Coating Defects in Batteries Electrode Production and their Effect on Cell Performance

The transition from combustion engines to electric vehicles drives the growing demand for high-quality lithium-ion batteries. Currently, defective cells are identified at the end of the battery production process during the aging step. Recycling these defective cells is costly and resource-intensive. Therefore, detecting defects earlier in the production process leads to significant cost savings. For that purpose, Non-Destructive Testing (NDT) methods can be applied in-line during battery production. This study examines two NDT methods for detecting coating defects on the anode: laser thermography and optical cameras. Both methods are suitable for in-line inspection. Artificial line and pinhole defects, as well as particle contamination, are introduced for testing the performance of the method using probability of detection curves. The results demonstrate that the optical camera system is superior at detecting particle contamination and point defects, while laser thermography is more effective for identifying line defects. Besides the detectability, the effect of these particles on the cell performance is investigated. The assembled cylindrical cells underwent life cycle testing and were benchmarked against defect-free reference cells. The findings indicate that point defects do not significantly affect cell behaviour. However, line defects and particle contamination on the anodes were observed to impact both the specific capacity over cycles and it’s thermal behaviour.