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With the growing popularity of Li‐ion batteries in large‐scale applications, building a safer battery has become a common goal of the battery community. Although the small errors inside the cells trigger catastrophic failures, tracing them and distinguishing cell failure modes without knowledge of cell anatomy can be challenging using conventional methods. In this study, a real‐time, non‐invasive magnetic field imaging (MFI) analysis that can signal the battery current‐induced magnetic field and visualize the current flow within Li‐ion cells is developed. A high‐speed, spatially resolved MFI scan is used to derive the current distribution pattern from cells with different tab positions at a current load. Current maps are collected to determine possible cell failures using fault‐simulated batteries that intentionally possess manufacturing faults such as lead‐tab connection failures, electrode misalignment, and stacking faults (electrode folding). A modified MFI analysis exploiting the magnetic field interference with the countercurrent‐carrying plate enables the direct identification of defect spots where abnormal current flow occurs within the pouch cells. [ABSTRACT FROM AUTHOR]

Electric switching of ultrathin ferroelectric films is vital for electronic elements such as multiferroic tunnel junctions, but the large required field may induce ionic motions as addressed here. Unipolar current–voltage (I–V) characteristics of ultrathin (3 nm) PbZr0.2Ti0.8O3 (PZT) grown on La0.7Sr0.3MnO3 (LSMO) by pulsed laser deposition have been investigated in an ambient‐condition force microscope. Topographic changes have been recorded after the I–V measurements. No ferroelectric switching is found, but resistive switching with features in agreement with earlier work on similar perovskite titanates. The onset of hysteretical I–V loops is correlated with a clear height increase in the contacted area under the Pt‐covered tip. The onset voltage of 4.5 V (−2.5 V) for positive (negative) tip bias is clearly different for the two voltage polarities. The observed height changes after applying electrical voltage reveal a volume expansion that must be attributed to chemical changes in both the PZT and the LSMO layers. A fast and a slow process of ionic motion or electrochemical reaction contributing to the observed features is identified. The slow one occurs at negative voltage, causes very large height increase, and is hypothetically attributed to processes following the electro‐splitting of the adsorbed surface water. [ABSTRACT FROM AUTHOR]