Fast Nondestructive Battery Diagnostics with MRI and Magnetometry: Detect State of Health, State of Charge, and Current Distributions

Abstract

Rechargeable batteries are notoriously difficult to assess. We are presenting new battery assessment technology based on MRI and magnetometry techniques, which allow non-destructive scanning of rechargeable cells. The techniques are fast, can detect changes in the electrode chemistry that occur as the battery is charged and discharged, or sense a range of different defects at early stages. In particular, we can determine site-resolved state-of-charge (where charge is stored in the cell), current distributions, as well as tiny transient effects. The vision is to use a benchtop-type instrument, which could be deployed in a variety of ways. The aim is to improve safety and performance, help in predicting battery life, clarify failure modes, and aid in the development of next-generation cells. Both MRI and magnetometry provide complementary measurement modalities with their strengths and limitations. MRI allows sensitive state of charge determination in a localized manner, and magnetometry allows to detect extremely weak electrical currents, both DC and AC at the level of nA in principle. Both these techniques provide new opportunities for battery diagnostics and research and could help reducuing the development cycle for new batteries and determining obscure battery failure modes. Figure 1