Location-Dependent Cobalt Deposition in Smartphone Cells upon Long-Term Fast-Charging Visualized by Synchrotron X-ray Fluorescence

In this work, we investigate the transition-metal dissolution of layered cathode material LiCoO2 upon repeated fast-charging three smartphone batteries from different manufacturers using synchrotron micro X-ray fluorescence (?-XRF). Using spatially resolved technique, Co and subsequent location-dependent deposition on anode are observed. ?-XRF mapping selected parts electrode sheets, such as folds edges jelly roll, reveals difference in way is deposited specific regions electrode. While some show no depositions, gradually accumulating depositions. Careful quantification dissolved that capacity loss scales with amount anode, is, total within cathode. Soft absorption spectroscopy depositions shows mainly a reduced 2+ state. optimization protocol mitigates Li plating significant can be observed between an optimized nonoptimized algorithm.