Battery inspection trends are evolving from two-dimensional X-ray visual inspection to three-dimensional inspection using computed tomography (CT). Issues such as electric vehicle fires have increased interest in battery reliability, and technology development has dramatically shortened the time required for 3D CT inspections, leading to an increasing number of applications in mass production lines.
According to the industry on the 22nd, 3D CT equipment is being introduced one after another at three domestic battery companies. LG Energy Solutions, Samsung SDI, and SK energy have all introduced CT for electrode alignment inspection. LG Energy Solutions is using SFA equipment, Samsung SDI is using a combination of anomaly and SFA, and SK energy is using anomaly CT. CT is being used to inspect a variety of behavioral battery types, including prismatic, pouch, and cylindrical토토사이트.
SFA employees use a 3D In-Line CT scanner to examine batteries for abnormalities. (Courtesy of SFA)
CT scans are primarily used in the medical field. X-rays are sent through the human body to obtain cross-sectional images, which are then reconstructed in three dimensions to analyze the images. The CT inspection equipment used for battery inspection is also a concept that collects X-ray images taken from various angles while rotating the battery around an axis and realizes a three-dimensional stereoscopic image. This is a significant difference from the 2D images obtained by conventional X-ray equipment while the battery is fixed.
The 3D CT inspection machine takes pictures of the inside of the battery cell, which is difficult to see with the naked eye, and fully inspects the arrangement of the positive and negative plates, which is responsible for filtering out cells with fire hazards in the inspection process. Although the unit cost is about three times that of X-ray equipment, the adoption is expanding due to the advantage of improving inspection accuracy due to the higher image precision compared to X-ray. In particular, the demand for 3D inspection in the electrode alignment inspection stage has increased due to the recent concerns about battery fire accidents.
Existing foreign 3D inspection equipment usually takes around 7 minutes to inspect a single cell, making it difficult to adopt due to productivity issues. Considering that more than 15 battery cells are produced in a battery factory on average every minute, it was physically impossible to inspect all of them.
The 3D CT inspection equipment developed by domestic companies has reportedly overcome this problem and reduced the inspection speed to a few seconds. The average inspection time per cell for the SFA CT inspection machine is around 4 seconds. The Innometry CT machine simultaneously inspects four reference cells of a pouch-type battery. It reportedly takes four seconds to inspect two electrodes. This translates to two seconds per cell. This allows for full inspection at the speed of a battery production line.
CT is inevitably slower than X-ray equipment, but it is compensating for its speed by improving the shooting method by enclosing multiple cells and developing equipment that inspects simultaneously with multiple heads. Work is also underway to improve speed and accuracy with its own artificial intelligence (AI) software that analyzes the images to determine whether they are defective.
“3D CT inspection equipment has higher image precision than X-ray equipment, which can improve inspection accuracy,” said an official from the battery equipment industry. “X-ray equipment still has the advantage in inspecting foreign objects and gaps that look at the entire battery, but CT is being introduced to inspection plants that look at parts of the battery, such as electrode alignment.”