Detection of Copper Deposition on Anodes of Over-Discharged Lithium Ion Cells by GD-OES Depth Profiling

A method based on glow discharge optical emission spectroscopy (GD-OES) depth profiling is developed to detect copper deposition on graphite electrodes for the first time. Commercial 18650 cells with graphite anodes were subject to Cu dissolution by over-discharge to 0 V. On a first approach, the depth profiles for Cu show significant differences for over-discharged cells compared to a baseline graphite electrode from cells discharged to the end-of-discharge voltage. An accumulation of Cu is found on the anode surface by GD-OES, which is consistent with SEM and EDX. The trend of the total Cu amount is compared with ICP-OES measurements.