X-ray imaging in e-mobility

GiantEye technology simplifies the use of XXL and HE CT technology by rotating the X-ray system around the object to be measured. This minimizes stress on the objects being measured, e.g., due to mechanical influence. The GiantEye tomography portal will combine the possible uses of previous systems and enable near-series use of the technology. The advanced X-ray components used and the optimized geometric design of the measurement system reduce measurement times or, optionally, increase the resolution of the measurable data.

High-energy computed tomography, also known as HE-CT, is used to scan compact but difficult-to-penetrate objects such as battery modules. The method enables high-resolution CT measurements of compact assemblies such as individual battery modules with an object scan of approx. 100 µm. The modules typically have dimensions of 300 mm × 200 mm × 2000 mm. By using special scanning methods such as Helix CT, it is possible to precisely image the battery cells, which are usually arranged orthogonally within the modules, and thus derive typical parameters such as distances and bulges. For the examination, the module is first tilted into a vertical position and fixed to the turntable of the CT system using a special mount. The measurement data is acquired using a flat panel detector, which enables very efficient measurement with measurement times between half an hour and two hours.

XXL-CT is used to examine entire storage systems and complete vehicles. The measuring system has a 4 m wide line detector and a manipulation system that can hold objects weighing up to 3 t in order to generate a CT cross-sectional image. The X-ray components can scan the object in quarter-millimeter increments over a height of up to 4.5 m. Thanks to the fan-shaped X-ray beam used, the system enables maximum penetration of over 1 m of aluminum and 0.4 m of iron. The examination of complete storage systems is used to analyze the position and orientation of the individual cells, e.g., before and after cycle tests. For production start-up and quality assurance, complete storage systems are analyzed for the internal characteristics of adhesions and foaming. Thanks to the high image quality that can be achieved, it is possible to clearly image and analyze all materials used in the storage system.

AIR technology transfers some of the capabilities of XXL-CT to a platform that is as simple and cost-effective to use as possible. The measuring system, which can be set up later in a simple garage, enables the rapid detection of single-layer, flat battery storage systems, even when installed. In addition to the potential to quickly transfer some of the capabilities of XXL-CT examinations to your own production environment, the AIR system opens up new fields of application for X-ray technology, such as the secondary vehicle market and damage assessment. Typically, the AIR system is used to take a two-dimensional bird's-eye view image of the storage unit. To do this, the vehicle is simply parked in the system and left there for the measurement. The data obtained enables a quick assessment of cell spacing, cell swelling, mechanical deformation of the battery frame, e.g., as a result of an accident, or other safety-critical features.

RoboCT technology expands the capabilities of industrial computed tomography for large and complex components, such as complete battery systems or entire vehicle structures. The measurement system is based on two cooperating industrial robots that flexibly move the X-ray source and detector around the test object. This allows for application-specific scan trajectories – ranging from quick overview images to high-resolution detailed analyses. Complete battery systems or crash-tested modules can thus be inspected non-destructively without having to be moved or disassembled. First, X-ray images provide an overview of anomalies such as cell displacement, damage, or structural defects. Selected areas can then be analyzed in 3D using CT and laminography at a resolution of up to 30 µm. RoboCT thus enables efficient quality control, failure analysis, and damage assessment of modern battery systems.

The precise acquisition of CT data with minimal artifact occurrence is an important basis for the evaluation of the acquired objects. Another important factor is the evaluation of the data. While individual examinations, such as damage assessment, are evaluated manually by experienced CT laboratory staff, the Strategic Initiative is developing evaluation methods that enable the almost fully automated evaluation of characteristic features and parameters. These are fed directly back into the development department, minimizing the effort required on the user side. Typically, the following characteristics are automatically evaluated in battery modules and systems: cell spacing, cell position, cell condition (swelling), bonding, foaming.