Battery passports for greater sustainability

Incorporating special magnetic particles into battery cells makes it possible to use Magnetic Particle Spectroscopy (MPS) to identify those cells and thus track them over their entire life cycle. The Development Center X-ray Technology is working on solutions for using this technology simply, safely, and efficiently. The information gained from the process can be used for targeted, environmentally friendly recycling of battery materials, which means it can play a key role in achieving greater sustainability.

But how does the technology manage to identify the particles in order to look into the battery’s past? Daniel Haddad, Group Manager at the Development Center X-ray Technology, explains: “Magnetic particle spectroscopy requires a certain material that most people know of as a contrast agent from Magnetic Resonance Imaging (MRI): iron oxide nanoparticles.” If these particles are placed in an external alternating magnetic field, they magnetize in line with that field, which is something a receive coil can detect. As the particles are superparamagnetic (i.e. they have only one magnetic domain), the detected signal is nonlinear. Applying a Fourier transform produces a spectrum. “Different particles have different spectra and can therefore be used to mark objects with a specific code,” Haddad says. Particles can also be designed in such a way that their spectrum can provide information about, for example, the nature of their surroundings and environmental conditions.

What does all this achieve? “The problem we currently have with battery recycling is that our process is highly inefficient,” Haddad says. In most cases, recyclers have hardly any information about exactly what materials lie inside their recyclate. They then use powerful chemical agents to extract important elements such as cobalt or nickel, while the rest is often incinerated or stored as waste. “Manufacturers, on the other hand, know exactly what their battery cells contain,” Haddad continues. This information gap is set to be closed with magnetic particle spectroscopy.

The battery passport as documentation of a life cycle

This means that even at the end of a battery’s service life, when it no longer has a label or has already been shredded, it’s possible to clearly identify an individual model and the batch it came from. With the help of the magnetic nanoparticles and the specific code from magnetic particle spectroscopy, the batteries could be assigned to a “battery passport,” as Haddad calls the entry in a database. It would then be possible to determine who manufactured the battery and how, how its cell chemistry has changed over the course of its use and thereafter, and what the optimum recycling process should look like. It would even be possible to find out whether the battery could be reactivated by making modifications. This would result in a near-perfect utilization of the numerous rare raw materials used in batteries. To avoid influencing the cell chemistry in any way, it would also be possible to introduce the particles outside the battery, for example into the sealing seam of the cell’s aluminum plastic pouch. “This way, we wouldn’t interfere with the cell’s performance,” Haddad says. A side benefit would be the counterfeit protection provided by the specific code, which could make the process highly appealing in other areas as well.

The vision is that the Development Center X-ray Technology and its partners will supply the particles, readout device, software, and database as a complete package. The customer will then introduce the particles into the battery cell materials in order to mark them. From this point on, the battery has a constant companion that will keep track of it.

Interview conducted by Lucas Westermann, editor, Fraunhofer IIS Magazine