69 conventional techniques that require extraction of samples and embedding them in resin or grinding them. “This substitution not only preserves the integrity of the batteries but also streamlines the inspection process by eliminating the need for time-consuming and potentially damaging procedures.” The technology provides improved accuracy in both quantifying and qualifying defects, he adds. This enables more detailed analysis of internal structure and capturing measurements of hidden features that conventional methods may struggle to evaluate. “In certain applications, CT technology can serve as a holistic testing method, consolidating multiple inspection steps into one comprehensive scan” he notes. “This integration not only enhances the thoroughness of the inspection but also reduces the overall effort and tooling required.” Electrode overhangs Technologies such as X-ray, CT and ultrasonics are effective at detecting electrode overhang errors, which is crucial to ensuring precise electrode positioning within the cell, and at identifying broken tab welds. They are also good for electrode bend-angle verification, checking for the proper alignment of electrodes for optimal performance, for locating any inclusions and contaminants within the cell, and for finding damage to electrodes. Beyond cell-level defects, they can also spot problems in electronics within modules, and with module assembly, the X-ray, CT and ultrasonic systems provider points out. Advanced solutions, including 3D inline CT systems, automate analysis of cathode/anode overhang, bending and exit angles, and the location, identification and assessment of contaminants and delaminations that separate layers of materials that should be in close contact. “With hundreds of features inside a battery that can be measured, our technologies provide a comprehensive assessment. This includes dimensional measurements, structural evaluations, and other critical parameters,” according to an expert from a 3D inline CT systems provider. Thermal imaging also helps to detect faults in production at an early stage in order to avoid rejects and minimise rework, a thermographic specialist notes. The company’s infrared cameras can be flexibly adapted to a wide variety of inspection and measurement tasks. They can also be individually integrated into existing quality assurance and surveillance systems, enabling the merging of live visual and thermographic video imagery. For monitoring stored batteries, thermographic cameras that provide detailed and colour-coded images based on temperature are integrated into customised systems that operate continuously without supervision, automatically triggering an alarm when temperature values exceed critical thresholds. These cameras enable the early detection of increasing temperatures and the localisation of heat sources that are not detectable by visual sensors. Supporting computer systems process the data to display temperature-time profiles in all areas of battery storage facilities. Companies with large portfolios of inspection products are in a good position to provide tools for correlative workflows that integrate inspections across different technologies. With batteries this makes it possible, for example, to inspect the chemical compositions of raw materials with highresolution microscopy. Once these are converted into active materials, optical imaging can be used to inspect for tears or foreign material in the electrodes. After cell assembly, CT can be employed to check for alignment and overhang defects. With the digitisation of all this data, if a failure occurs in the field, engineers can look back at all levels in the manufacturing process to determine the root cause. Technological limitations All these technologies have their limitations, which tend to be highly dependent on specific use cases. The efficiency of the inspection process can be influenced by the characteristics of the defects being targeted and the intricacies of the production workflow, another expert notes. “Certain defects or manufacturing steps may require more time for a thorough and accurate scan, impacting the overall speed of the inspection process,” this expert says. “Balancing the need for precision with the demand for a timely assessment is a challenge that may be encountered in CT industrial inspection of batteries.” The limitations of CT technology are imposed by the laws of physics, and are principally associated with the penetration of samples based on their density; high density samples that hinder penetration can compromise the inspection process. Further, high spatial resolution requirements tend to limit the size of the sample that can be scanned given that X-rays strongly attenuate as the thickness increases, a factor that also strongly depends on material composition. E-Mobility Engineering | January/February 2024 Teledyne DALSA’s AxCIS linescan module combines sensors, lenses and lights. The CMOS-based contact image sensor provides detailed high-speed monochrome and colour imaging in electrode production (Image courtesy of Teledyne DALSA)
RkJQdWJsaXNoZXIy MjI2Mzk4