Non-invasive current density imaging of lithium-ion batteries

The rapid pace of replacing fossil fuel propelled transport by electric vehicles is critically dependent on high-performing, high energy density batteries. Optimal and safe use existing battery cells development much-needed novel chemistries geometries require a multitude diagnostic monitoring tools. While structural chemical information readily extracted through host imaging techniques, non-invasive functional detection interior processes remains limited. Here we introduce sensitive magnetometry performed outside the battery, revealing internal current distribution. As key application, sensor array to image flow pouch cell cycling between charge states. We find good agreement measured modelled fields with sufficient resolution detect percent-level deviations around areas. This opens path towards reliable assessment throughout life cycle, from manufacturing quality assurance optimised use.