Fraunhofer’s X-ray device makes cell interiors visible / PowerCo as user
Fraunhofer EMI has developed a specialized X-ray technology that enables real-time visualization of dynamic processes within large prism-shaped battery cells. This technology is now set to be translated into industrial use in collaboration with Volkswagen’s battery subsidiary, PowerCo.
The Fraunhofer Institute for Short-Time Dynamics, Ernst-Mach Institute, describes this innovative X-ray technology as a “world-exclusive high-speed X-ray facility.” It makes visible what happens in fractions of a second inside large battery cells under stress, thereby accelerating the development of safer cell generations for Europe’s automotive industry, according to the scientists in a accompanying statement.
The approach aims to answer the question of what happens inside a battery cell when it fails. Until now, cell manufacturers and vehicle integrators have relied on simulations, destructive testing methods, or indirect measurements. The technique developed by Fraunhofer EMI, however, is intended to allow a direct view of the operating cell. According to the project team, the system combines high-performance X-ray technology with a specially designed battery testing chamber, along with comprehensive sensors for simultaneous measurement of temperature, pressure, voltage, and gas flow. “With up to 1,000 images per second, processes such as gas formation, material displacement, and crack development inside the cell are captured in high resolution—processes that have previously remained completely hidden,” writes the institute.
Dr. Sebastian Schopferer, head of Battery Safety at Fraunhofer EMI, emphasizes: “With our in-situ method, we can track what happens within fractions of a second inside a cell—in real time and with the highest resolution. This transforms our fundamental understanding of battery design and safety.” A key engineering achievement was the development of a protective chamber that reliably shields sensitive X-ray components from the extreme conditions caused by thermal runaway in lithium-ion cells.
The relevance of this approach is evident from the strong interest shown by industry: Fraunhofer EMI states that it has already analyzed material behavior during thermal cycling and propagation characteristics in multi-cell structures for several German automakers (“including VW and Audi”). “The data obtained enable the evaluation of cell designs based on actually observed processes and the targeted refinement of existing simulation models — a direct benefit for product development and approval processes,” according to them.
The partnership is particularly close with VW’s battery subsidiary, PowerCo. As the next step, Fraunhofer EMI and PowerCo aim to bring this technology into industrial use together. The institute contributes its expertise in materials research, battery abuse testing, and high-speed imaging. PowerCo provides input on requirements for mass production as well as access to actual cell types.
According to the partners, initial results from this collaboration are already being used today to develop improved mass-produced cells for PowerCo. However, this process still involves certain logistical challenges. But there is a clear timeline: an appropriate X-ray system is scheduled to be installed at PowerCo’s facility in Salzgitter by 2028. The system can be scaled for various cell formats and new cell chemistries — “a decisive advantage for the development of future battery generations,” says the Fraunhofer Institute.
HW Vassen, CTO at PowerCo, commented: “With in-situ high-speed X-ray imaging, we are elevating battery research to a new level: for the first time, we can visualize the dynamic processes inside cells in real time and at slow motion. This unprecedented level of insight allows us to specifically optimize the safety and design of battery cells, as well as bring innovations to industrial application much more quickly. Together with Fraunhofer EMI, we are thus advancing high-tech ‘made in Europe’ and strengthening Europe’s role in the battery industry.”
As is well known, PowerCo was founded in 2022 by the Volkswagen Group and is responsible for developing and manufacturing the group’s battery cells. Headquartered in Salzgitter, the company is currently building three cell factories with a combined capacity of up to 200 gigawatt-hours per year: in Salzgitter (Germany), Valencia (Spain), and St. Thomas (Canada).