One of the biggest obstacles in the way of battery technology development is the limited amount of information that one can obtain from the battery mechanism without taking it apart. Here we are presenting a novel non-destructive battery assessment technology that is capable of obtaining crucial information from batteries even when the cells are encased in conductive material. One important application is commercial-type cell-phone batteries, which can be analyzed with this method. The technique is based on measuring the magnetic susceptibility of active ingredients inside an electrochemical cell that is affected by the oxidation state of the materials to give insights into the state of charge (SOC) of the battery, its failure mechanisms and the current distributions. The technique has been demonstrated on various cell types, defects, chemistries, and current level. The measurement is based on Magnetic Resonance Imaging (MRI) techniques, is fast (a couple of seconds), and could be adapted to a range of cell types. The figure shows the schematic setup and examples of images of different cells which are used to diagnose the SOC and the state of health. The technology represents a new opportunity for nondestructive cell diagnostics, and hence could be of great help in the development of next-generation batteries. We demonstrate the identification of defect, state of charge, and classification of cells based on different types of features. The method can also provide localized current distribution measurements.

Figure caption: Magnetic field map measurements for the fully charged cells. (A)-(C) sample placement, and image orientation; (D)-(E) Field maps measured for the cells. Field maps are referenced to the empty holder, giving an absolute field map for the Li-ion cell. (F) Magnetic field maps for the defect cells, with the mean and standard deviation indicated (taken over all of the voxels in each image). The fields are given relative to one of the non-defect cells (not shown).