Nondestructive Defect Detection in Battery Pouch Cells: A Comparative Study of Scanning Acoustic Microscopy and X-Ray Computed Tomography

Localizing defects inside battery cells before performance decreases or safety issues arise remains a challenge. This study compares two non-destructive testing methods for the detection and 3D visualization of defects at different depths inside a pouch battery cell: Scanning Acoustic Microscopy (SAM) and X-ray computed tomography (CT). SAM is used in reflection mode to detect defects at depths of up to four electrode sheets using a 15 MHz transducer. With CT, defects on all eight stacked electrode sheets inside the pouch cell can be located. The longer measurement duration is though a drawback. Both methods can complement each other in detecting defects in thin pouch cells as End-of-Line tests in production or for second-life applications. As an inline quality test of assembled cells, SAM shows promise as a cost-effective and efficient method for detecting defects. Ultimately, both methods have the potential to improve the non-destructive quality assurance of lithium-ion battery cells, contributing to the safety and performance of battery technology.