Speaker
Description
Lithium-ion batteries (LIBs) are used to power electric wheelchairs owing to their high energy density and long lifespan. LIB modules for wheelchairs consist of densely packed cells, and non-destructive testing is required to detect internal defects. This study aims to suggest the proper instrument configuration and CT reconstruction method for LIB module-level inspection which remains challenging due to scatter radiation and artifacts.
Monte Carlo simulations were performed with Geant4 to optimize radiography instrument and CT reconstruction workflow. A 3×3 cylindrical 18650 LIB module with 0.18 mm cracks in each cell was modeled with a CsI(Tl) detector. The instrument was optimized by varying X-ray energy, filtration material and thickness, detector pixel size, and magnification. For reconstruction workflow optimization, preprocessing, reconstruction, and postprocessing methods were compared. Feldkamp-Davis-Kress (FDK) reconstruction was used as the baseline. Image quality and defect detectability were quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and detectability index (d′).
The optimized instrument configuration was 150 keV X-ray energy, 1.6 mm Sn filtration, 85 μm detector pixel size, and 2.1 magnification. Raw projections, OS-SART, and Gaussian smoothing ahcieved the highest reconstruction performance. Compared with FDK, SNR, CNR, and d′ increased by 233%, 119%, and 117%, respectively. These results indicate that instrument and reconstruction optimization can improve defect detectability in compact LIB modules.
ACKNOWLEDGEMENT
This work was supported by the Nuclear Safety Research Program through the Korea Foundation Of Nuclear Safety (KoFONS) using financial resources granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea (RS-2021-KN050310).