Foreign body detection can spot even the tiniest interloper – increasing safety and reducing waste in battery production

A particle smaller than a speck of dust can cause an entire battery to burst into flames. This might initially sound a little far-fetched, but unfortunately it’s happening with increasing frequency to a growing number of energy storage systems. The reason is that during battery production, foreign bodies can find their way into the electrode material – potentially causing serious damage, including from fire. Solving this problem is the task of foreign body detection, which involves using imaging methods to search for these tiny particles. 

Microplastics, particulates, and pollen: despite their tiny size, such particles can have a massive effect. As they tend to be practically invisible, finding and eliminating them is a rather complicated endeavor. This applies not only to the three everyday microparticles mentioned above, but also to the tiny foreign bodies that often find their way into the production of electrodes for batteries. Typically between 50 and 200 micrometers in size, these foreign bodies are virtually undetectable using conventional methods. Given how much havoc they can wreak, this situation is less than ideal. Metallic foreign bodies, for instance, can penetrate the battery’s separator film and cause an internal short circuit.

X-ray technology lends a helping hand

A new approach to foreign body detection is to use X-ray technology. An assembly comprising an X-ray source and a detector continuously monitors the electrodes during roll-to-roll processing, which allows any foreign bodies in the material to be detected early on in production. Analysis of the 2D images generated during monitoring is completed quickly. “Just like we did for other X-ray technologies in battery production, we’re aiming to integrate process feedback here, too,” says Steven Oeckl, Head of Production Monitoring at the Development Center X-ray Technology. This involves combining artificial intelligence with production parameters to create a model that can help predict which process settings will be required to prevent foreign bodies from getting in. In this way, the technology helps reduce waste, which in turn makes battery production more sustainable. At present, if foreign bodies manage to infiltrate the electrode material, the battery usually has to be thrown away.

The presence of foreign bodies is a common problem in battery production. “Many of our customers confirm this,” Oeckl says.

“Our foreign body detection thus goes a long way toward achieving more reliable production of safer batteries. And given the vast number of gigafactories now springing up across Europe, this is a red-hot topic.” 

Article by Lucas Westermann, editor, Fraunhofer IIS Magazine