Fraunhofer EMI’s X-ray system films inside battery cells at up to 1,000 images per second

The Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut (EMI) has developed a high-speed X-ray system that shows what happens inside large-format prismatic battery cells under load, in real time. Fraunhofer EMI is working with PowerCo, the Volkswagen Group’s battery cell manufacturer, to bring the system into industrial use.

The system pairs X-ray imaging with a purpose-built battery test chamber and sensor systems that simultaneously capture temperature, pressure, voltage and gas flow. Recording up to 1,000 images per second, it reveals gas formation, material displacement and crack propagation inside the cell.

A protective chamber shields the X-ray components from the conditions generated during a lithium-ion cell thermal runaway. Fraunhofer EMI calls that chamber a key engineering milestone in the system’s development.

Cell manufacturers and vehicle integrators have had to rely on simulation, destructive testing and indirect measurement to work out what happens inside a failing cell, according to Fraunhofer EMI.

“Our in-situ method allows us to see what happens inside a cell in fractions of a second—in real time and at the highest resolution,” said Sebastian Schopferer, Fraunhofer EMI’s Head of Battery Safety. “This fundamentally changes how we understand battery design and safety.”

Fraunhofer EMI has already used the system for several German carmakers, including Volkswagen and Audi, to characterize material ejection during thermal runaway and propagation behavior in multi-cell configurations. The resulting data, Fraunhofer EMI says, lets engineers assess cell designs from directly observed processes and refine simulation models.

In the next phase, the two partners will transfer the technology into industrial use. Fraunhofer EMI brings expertise in materials research, battery abuse testing and high-speed imaging, and PowerCo contributes production requirements and access to real-world cell types. Initial results are feeding into the development of production cells at PowerCo, the partners say.

The system is scheduled for installation at PowerCo’s Salzgitter site in 2028. The partners describe it as a modular platform that can be scaled to different cell formats and new cell chemistries.

“For the first time, we can make the dynamic processes inside cells visible in real time and in slow motion,” said HW Vassen, PowerCo’s CTO. “This unprecedented depth of insight allows us to optimize battery cell safety and design in a highly targeted way and bring innovations into industrial use much faster.”

Source: Fraunhofer EMI