Since the market launch of lithium-ion cells for electric cars, electric bikes and energy storage systems, the detailed analysis of aged or defective batteries is increasingly gaining in importance. In the case of damage assessment, it is often a question of whether incorrect use, production errors or weakness in the construction caused the adverse effect.
Our core areas of expertise include cell opening and post-mortem analyses as well as non-destructive 3D computer tomographic tests on batteries and cells. Our facilities comprise a very good infrastructure with professional work stations for cell opening. With a 3D X-ray computer tomograph are we able to look at the internal structure of batteries and their components.
We are specialised in cell opening and post-mortem analyses for analysing damage and assessing new or aged cells. The analytical results are essential for understanding ageing processes, potential safety risks and for optimising cell design.
All types of batteries are tested: from conventional lead-acid batteries and lithium-ion batteries to the new supercaps. All sizes can be professionally tested up to a capacity of 400 ampere hours, be they cylindrical cells, pouch cells or prismatic cell designs. For this purpose, our facilities include professional work stations for opening cells.
Damage mechanisms can be established from the result of the post-mortem analysis. For example, in a study with commercial 18650 lithium batteries we found that the ageing mechanism changes with the ambient temperature. The decomposition of the conducting salt on the surface of the anode occurs at higher temperatures, whereas at lower temperatures metallic lithium settles on the anode (see Figure).
Once the cells are opened, ZSW has a large range of physical-chemical analysis methods for investigating the damage mechanisms: using SEM, EDX, ICP-OES, XRD and GC-MS, we can comprehensively investigate all the cell components (anodes, cathodes, separators and electrolytes) at our facilities.
Looking into the inside of cells provides essential knowledge for optimising cells and production processes. We are able to look at the internal structure of batteries and battery components in a non-destructive manner by using 3D X-ray computer tomography.
In the laboratory, post-mortem analyses in cases of damage and quality assurance tests for new batteries are performed using an approximately 2.5 metre-long, 2 metre-high and 1.60 metre-wide computer tomograph. Such tests provide the basis for the targeted improvement of materials and processes as part of the electrode and cell production and are also used for developing new test methods for the battery industry.
„We are able to make the smallest anomalies and structure changes inside the cells visible in 3D.“
„Essential knowledge regarding cell optimisation and production processes can be gained.“
Two tubes of different strengths enable the internal structure of batteries and their components to be made visible. In particular, larger cells and complete battery modules can be X-rayed using a microfocus X-ray tube with a voltage of 300 kilovolts (KV) and a detail recognition of up to 1 µm. Using a nanofocus X-ray tube, tiny details up to 0.5 µm inside the cells can be made visible in 3D.
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