Researchers at Johannes Gutenberg University Mainz (JGU) and the Helmholtz Institute Mainz (HIM) in Germany have developed a non-contact method for detecting the state of charge and any defects in lithium-ion battery cells.
Professor Dmitry Budker and his team usually use atomic magnetometry to explore fundamental questions of physics, such as the search for new particles. Adapting the technique to measure the magnetic field around battery cells creates a non-contact technique to test the quality of battery cells.
The demand for high-capacity rechargeable batteries is growing and so is the need for a form of sensitive, accurate diagnostic technology for determining the state of a battery cell. The success of many new developments will depend on whether batteries can be produced that can deliver sufficient capacity and a long effective life span.
“Undertaking the quality assurance of rechargeable batteries is a significant challenge. Non-contact methods can potentially provide fresh stimulus for improvement in batteries,” said Dr. Arne Wickenbrock, a member of the work group at the JGU Institute of Physics and the Helmholtz Institute Mainz. “Our technique works in essentially the same way as magnetic resonance imaging, but it is much simpler because we use atomic magnetometers,” said Wickenbrock, who is part of the team conducting the investigations. Atomic magnetometers are optically pumped magnetometers that use atoms in gaseous form as probes for a magnetic field. They are commercially available and are used in industrial applications as well as fundamental research.
In the case of battery measurements, the batteries are placed in a background magnetic field. The batteries alter this background magnetic field and the change is measured using atomic magnetometers. “The change gives us information about the state of charge of the battery, about how much charge is left in the battery, and about possible damage,” said Wickenbrock. “The process is fast and, in our opinion, can be easily integrated into production processes.”