Validating Material Purity Using X-Ray Technology to Safeguard Against Catastrophic LiB Failure

摘要

Metal particle contamination in lithium ion batteries (LiB) can cause internal short circuits, which decrease the performance and safety of batteries. Thus, it is essential to control particles in the manufacturing process, especially for LiB used in transportation. Rapid inspection methods for metal particle contamination are needed to ensure the safety of batteries. In this study, we examined the applications of X-ray fluorescence analysis and X-ray transmission imaging as inspection methods for LiB to reduce internal short circuits. Three types of samples, (1) a separator, (2) an electrode plate, and (3) an electrode conductive material, were used to determine the detection time of 20 μm diameter contaminant metal particles within samples 250 mm × 200 mm in size and to evaluate the identification capabilities of the elemental analyses. As a result, the metal particles were detected in approximately 5 minutes for the separator, approximately 10 minutes for the electrode plate, and approximately 18 minutes for the electrode conductive material, respectively. Moreover, subsequent elemental identification of the particles was accomplished using the X-ray fluorescence analysis. These results demonstrate that metal particle inspection in a LiB can be performed in a short period of time. In conclusion, this rapid and effective analysis method could contribute to process improvement at high throughput. Furthermore, a reduction of internal short circuits should improve the performance and overall safety of batteries.