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battery measuring A new, simple method for measuring the state of lithium-ion batteries

Author / Editor: Luke James / Jochen Schwab

Researchers at the Johannes Gutenberg University Mainz (JGU) and the Helmholtz Institute Mainz (HIM) in Germany have developed a non-contact battery testing technique for measuring the state of lithium-ion batteries.

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There is a growing demand for high-capacity rechargeable batteries. Growing alongside this demand is a need for a method of accurate diagnostic testing of batteries for determining the state of battery cells, as future innovations will depend on whether new batteries can be produced and proven as suitable for applications—being able to look at metrics like capacity and effective lifespan will help manufacturers provide the answer.

Being able to detect damage in batteries could also solve some of the problems that plague today’s batteries. We all know of the recurring reports of explosive e-cigarettes and the infamous Galaxy Note 7 that was recalled when the device’s battery was found to overheat and combust.

Atomic magnetometry

Using the non-contact technique, it is reportedly possible to measure metrics like a battery’s charge state, defects, and capacity losses by using atomic magnetometry. This is typically used by Dmitry Budker and his team for exploring the fundamental questions of physics, such as searching for new particles. By adapting the technique to measure the magnetic field around battery cells, it reportedly creates a non-contact technique that can be used for testing battery cell quality.

"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 of the JGU Institute of Physics. "Our technique works in essentially the same way as magnetic resonance imaging, but it is much simpler because we use atomic magnetometers," added Wickenbrock.

Atomic magnetometers are optically pumped magnetometers that use gaseous atoms to probe for a magnetic field. They are widely available, often used in industrial applications and research environments.

Magnetometry for battery measurements

In the context of battery measurements, the batteries are placed in a background magnetic field. The batteries then alter this field and the change is measured by using atomic magnetometers, providing information about a battery’s charge state, how much charge is left in the battery, and whether there is any potential damage. "The process is fast and, in our opinion, can be easily integrated into production processes,” claims Wickenbrock.

"The diagnostic power of this technique is promising for the assessment of cells in research, for quality control, or during operation," it was stated in the team’s research paper, published earlier this year in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).