Magnetic field map measurements for fully charged cells. Source: Andrew Ilott and Alexej Jerschow, New York UniversityA new non-invasive technique has been developed for diagnosing what ails rechargeable lithium-ion batteries. The magnetic resonance imaging (MRI) method measures minuscule changes in magnetic field maps to create a picture of what lies inside a structure without taking it apart or destroying it.

The technique was demonstrated by measuring small magnetic field changes surrounding the battery’s electrochemical cells. Observations were made at various levels of battery charge and under varying levels of cell damage. The researchers successfully matched magnetic field changes surrounding the batteries to different internal conditions, revealing state of charge and certain defects. These included bent and missing electrodes as well as small foreign objects in the cell, which are flaws that can occur during the normal manufacturing process.

Future enhancements to the method could provide a powerful means of predicting battery failures and battery lifetimes. It could also contribute to the development of next-generation high-performance, high-capacity and long-lasting or fast-charging batteries.

Scientists from New York University and Rochester Institute of Technology participated in this research, which is published in Nature Communications.