Operando Detection of Lithium Plating and Stripping in Fast‐Charging Li‐Ion Cells with a Reference Electrode

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Understanding degradation mechanisms in Li‐ion cells is essential for advancing fast‐charging technologies. One of the primary limitations of fast charging is the risk of lithium plating, driven by the negative electrode potential. In this study, a reference electrode (RE) is integrated into 30 mAh pouch cells to investigate aging under various charging regimes. This three‐electrode setup allowed monitoring the potential of both electrodes, with a particular focus on the negative electrode. By coupling operando data with post‐mortem analysis, the cell's electrical behavior is linked to physical phenomena occurring within the cell. During fast charging at 2C, changes in the incremental capacity profile are observed and correlated with a critical threshold in the negative electrode potential, measured using the RE. Post‐mortem analysis confirmed that these changes are indicative of lithium plating. Furthermore, an additional current during the potentiostatic phase of the charge is identified, correlating with a rise in the potentials of both electrodes. This current bump is interpreted as evidence of a lithium stripping process. These findings highlight the importance of monitoring the negative electrode potential using an RE to detect and mitigate the risk of lithium plating during fast charging, contributing to the optimization of battery performance and safety.