Lithium-ion battery inspection

In recent years, the demand for lithium-ion batteries (LiB) has been increasing due to the rapid spread of HVs, PHEVs, and BEVs against the backdrop of environmental concerns and the imperative to strive towards carbon neutrality. With this growth the automotive industry has experienced, accidents of heat generation and ignition caused by LiBs. Efforts are being made to improve the safety of LiBs by conducting inspections not only of finished products but also of raw materials and manufacturing processes. 

LiB manufacturing process and typical inspections

Most of the heat generation and ignition accidents caused by LiBs are due to a short circuit between the positive and negative electrodes of LiBs. There are various causes of shorts between electrodes. Here we introduce typical inspections conducted in the manufacturing process to screen out LiBs that may short-circuit in the future.

Sheet material inspection

Foreign material inspection

Pinhole inspection

Optimal inspection method for each type of LiB

There are various types of LiBs, depending on their constituent parts such as electrodes and their shapes. Since the optimal inspection method differs for each type, the choice of inspection method is very important in LiB quality control. For example, the three most common battery shapes are "cylindrical", "square", and "pouch (laminated)". However, the internal inspection method using X-rays differs depending on the internal electrode structure (stacked or wound). The X-ray detector also varies depending on whether in-line or off-line inspection is used.

Below are the typical inspection methods and X-ray sources and detectors used for the distance between the positive and negative electrodes of "cylindrical", "square", and "pouch (laminated)" LiBs.

Types of LiB

The typical inspection methods for each LiB type

Winding type (Cylindrical)

X-ray inspection for cylindrical lithium-ion batteries

Winding type (Square)

X-ray inspection for prismatic/pouch lithium-ion batteries (winding type)

Stacking type (Pouch)

X-ray inspection for prismatic/pouch lithium-ion batteries (stacking type)

Imaging example

In-line CT inspection

As the causes of LiB failures gradually become clearer, there is a growing demand to inspect more complex structures and find minute defects. Currently, 3D images are required for off-line and spot-check inspections. In the future, 3D images will also be required for in-line full inspection.

We are one of the few companies in the world that develop and manufacture both microfocus X-ray sources and high-speed operation X-ray flat panel sensors, which are essential to obtain high-definition X-ray CT images. We also offer solutions for the needs of in-line CT inspection that will eventually be required.

Configuration example

Imaging example

Solutions provided by Hamamatsu Photonics

Hamamatsu Photonics is an optical specialist that handles both "light-receiving" and "light-emitting" devices. We respond to customer needs for LiB inspection by developing and proposing products that combine our experience accumulated over many years with the latest technologies, and propose solutions that include technical support.

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Demo Information

Hamamatsu Photonics proposes optimal solutions for X-ray non-destructive inspection through demonstration.

We provide trial photography using various X-ray sources, sensors, and cameras as a preliminary evaluation for X-ray non-destructive inspection requests from our customers.


Based on our experience accumulated over many years in the X-ray business, we not only introduce the most suitable devices, but also propose the best solutions, including useful tips and advice. Please feel free to contact us.

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