Nondestructive testing technique for lithium-ion batteries

departments - last look

Researchers at New York University and in Germany collaborate on a magnetometry-based system to measure used battery imperfections that could impact charging, longevity.

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August 12, 2020

Researcher Yinan Hu demonstrates lithium-ion battery testing at Johannes Gutenberg Universitat in Mainz, Germany. Cell testing could lead to more accurate “fuel” gages on future electric vehicles (EVs).
Photos courtesy of Johannes Gutenberg Universitat, Mainz

After thousands of hours of use and hundreds of charge/discharge cycles, lithium-ion (Li-ion) batteries in electric vehicles (EVs) or aircraft systems can develop flaws that hinder energy storage and effectiveness, limiting range in vehicles.

Researchers at New York University (NYU) and the Johannes Gutenberg Universitat in Mainz, Germany (JGU), have collaborated to develop techniques to measure battery performance after use, possibly leading to onboard systems that will adapt charge/discharge cycles for improved performance in future systems.

“At the moment they are research tools,” says Alexej Jerschow, an NYU chemistry professor and one of the authors of a recent paper on magnetometry-based testing for advanced batteries. “[It] could certainly be made into a lower cost instrument, that could even perform in-situ measurements. It depends a lot on the specific use case.”

The researchers are using atomic magnetometry to map weak induced magnetic fields around Li-ion battery cells in a magnetically shielded environment. Rapidly measuring cells nondestructively allows testing cells in operating conditions. The measurements create maps of the magnetic susceptibility of the cell that, when coupled with more research, can categorize the health of batteries. They also provide a more exact measurement of the cell’s charge, better indicating how much juice a battery has left.

Atomic magnetometers measure the magnetic fields within battery cells, identifying flaws and determining exact states of charge.

The technique could lead to diagnostic systems to assess cells in research, quality control, or during operation. A lab system for now, Jerschow says future iterations could be installed directly in EVs to manage charging/discharging of individual cells within a battery pack to protect failing units and maximize range.

“If the price can be driven down and the device can be scaled accordingly,” the system should be suitable for vehicles, Jerschow says. “At the moment, we are showing that we are able to detect new information from cells, but an in-situ and on-board implementation would be very desirable. Again, that will be a cost issue. It’s not possible at the moment, but could become a reality in the future.”

Arne Wickenbrock, a professor at the JGU Institute of Physics and the Helmholtz Institute Mainz, says, “Our technique works in essentially the same way as magnetic resonance imaging (MRI), but it is much simpler because we use atomic magnetometers.”

Johannes Gutenberg Universitat Mainz https://www.uni-mainz.de

Helmholtz Association www.helmholtz.de/en

New York University (NYU) https://www.nyu.edu

About the author: Robert Schoenberger is editor of Today’s eMobility and Today’s Motor Vehicles. He can be reached at 216.393.0271 or rschoenberger@gie.net.