Different battery packaging types

• Cylindrical batteries: For cylindrical lithium batteries such as 18650, the main inspections cover coil alignment and tab welding defects. On highly automated production lines, inline X-ray lithium battery inspection equipment is installed, and through software settings, each battery is automatically inspected to improve inspection efficiency, reduce manual intervention, and automatically identify defective products.

• Prismatic batteries: The positive and negative electrodes of prismatic batteries use two processes—winding and stacking—and different models of X-ray inspection equipment must be selected according to the process. For example, the testing equipment developed by UFJ for power winding and power stacking batteries can more specifically inspect issues such as electrode alignment and welding quality during the packaging of prismatic batteries.

• Pouch batteries: Pouch batteries are prone to leakage and other issues. In addition to inspecting the internal arrangement of positive and negative electrodes and coil alignment, special attention must be paid to the sealing of the packaging. X-ray inspection equipment combined with specific image processing algorithms can be used to analyze the sealing boundary of pouch batteries and determine whether poor sealing exists.

Inspection principle

X-ray inspection is based on the differences in X-ray absorption by materials. Using the attenuation characteristics of different materials (such as copper, aluminum, nickel, and lithium) to X-rays, grayscale images of varying contrast are formed. For cylindrical lithium batteries, common X-ray inspection methods include:

(1) 2D X-ray radiography

Single-angle or multi-angle projection is used, and internal structural images are acquired through a flat panel detector (FPD) or digital radiography (DR).

Suitable for rapid screening, inspecting major structural integrity and obvious defects.

(2) Computed tomography (CT)

Multi-angle rotational scanning is used to obtain the three-dimensional internal structure of the battery and generate tomographic images.

Capable of precisely detecting cell winding offset, welding defects, internal cracks, foreign objects, and more.

Suitable for high-precision analysis and failure analysis.

Main inspection targets

Electrode winding, tab welding, current collector welding, anode copper foil alignment, foreign object detection, and case packaging, addressing issues such as winding offset, interlayer short circuits, fractures, cold welds, uneven welding, and weld fractures.

Technical advantages

(1) Non-destructive inspection, efficient and precise

X-ray inspection can non-destructively obtain internal structural information of batteries, ensuring product integrity.

High-speed inline X-ray inspection enables automated batch screening and improves production efficiency.

(2) High-resolution imaging

Micro-focus X-ray sources are used to provide clear, high-resolution imaging with resolution down to the micron level (<5μm). Precise analysis of tiny defects (such as weld voids and electrode damage) is possible.

(3) Adaptability to fully automated production lines

Can be integrated into high-speed production lines, with robotic automatic loading and unloading, requiring no manual intervention and improving production efficiency.

Enables real-time monitoring of production data and improves yield control.

Typical application scenarios

(1) Battery manufacturing inspection

Applicable to large-scale production of standard cylindrical batteries such as 18650 and 21700.

Through inline X-ray systems, automated inspection on production lines is achieved, improving efficiency.

(2) Quality control (QA/QC)

Random sampling inspection is performed before shipment to ensure consistent product quality across batches.

X-ray computed tomography (CT) is used to evaluate whether key parts such as welds and electrode windings meet specifications.

(3) Battery failure analysis

In-depth analysis is conducted on abnormal batteries (such as those with short circuits, swelling, or low capacity).

Through CT scanning, weld cracks, short-circuit paths, and other issues are precisely located, improving failure analysis capability.