Supply Contract Liability Allocation for Transit Delays and Aging Cell Re Certification Gaps
Transit delays drive cell degradation and document expiry, requiring clear contract clauses to shift re-certification and scrap liabilities to suppliers.
X-Ray CT
Meaning
Non destructive imaging technique uses computer processed x-ray measurements to create a three dimensional map of the internal structure of a battery. This x-ray ct measures the density and the alignment of the electrode layers and the presence of any foreign contaminants without opening the cell. It allows engineers to inspect the mechanical integrity of the jelly roll and the position of the tabs and the safety vents.
The process generates a series of cross sectional images that are combined to show the volumetric state of the device. It is a vital tool for failure analysis and quality control in the production of high performance battery cells.
Internal Structural Mapping
Detailed view of the hidden components within the metal can or the pouch reveals defects that are invisible to the naked eye. When x-ray ct is used, it can identify misalignment of the anode and cathode layers that could lead to uneven current distribution. It also detects the formation of metallic dendrites or the displacement of the separator during the manufacturing process.
This information is used to refine the assembly parameters and improve the yield of the production line. Because the technique is non destructive, the cell can still be tested electrically after the scan is complete. This allows for a direct correlation between the physical structure and the performance of the battery.
High resolution scans provide the level of detail necessary to see individual particles of the active material.
Quality Control Inspection
Systematic use of this imaging technology helps manufacturers to ensure that every cell meets the strict safety standards required for electric vehicles. By integrating x-ray ct into the post production workflow, a company can verify the internal assembly of a sample of cells from each batch. This acts as a barrier against latent defects that could cause a field failure or a thermal runaway.
The technique is particularly useful for inspecting the welds and the seals that protect the cell from the environment. If a defect is found, the entire batch can be quarantined for further investigation. This prevents the shipment of faulty batteries to the customer and reduces the risk of expensive recalls.
Sourcing managers often require these scan reports as part of the technical documentation for new suppliers.
Resolution Limit Boundary
Capability of the imaging system to see fine details is defined by the voxel size and the power of the x-ray source. While x-ray ct provides an excellent view of the macro structures, it may not have the resolution to see the smallest chemical changes at the atomic level. The boundary of its usefulness is reached when the defects are smaller than the resolution of the detector.
Faster scanning speeds are often required for high volume manufacturing, which can lead to a reduction in image quality. Researchers must balance the need for high resolution with the time and cost required to perform each scan. Despite these limits, the technology remains the most effective way to see inside a sealed battery.
Ensuring that the scan parameters are optimized for the specific cell size is a requirement for obtaining useful data.