Fast Charging Formation of Lithium‐Ion Batteries Based on Real‐Time Negative Electrode Voltage Control

The formation of lithium‐ion batteries is a time‐consuming and important process during manufacturing. During the formation, surface layers on the electrodes are formed that affect the cell performance. State‐of‐the‐art formation procedures consist of several slow current cycles as it is believed to guarantee good surface layer properties while preventing degradation processes. Herein, five different formation strategies with process times between 52.79 and 1.68 h for coin cells with a lithium reference electrode are assessed. The fastest method is based on a fast charging approach that prevents lithium‐plating. Based on a real‐time negative electrode voltage control to a threshold of 20 mV, lithium‐plating is successfully prevented while ensuring a fast formation process. The formation is finished after just one cycle and results to similar cell and electrode resistance, impedance, and capacity retention compared to the other strategies. The fast charging formation approach leads to the lowest degradation when storing the cells at 80% state of charge and 60 °C for 28 days. The results conclude that the fast charging formation method with real‐time control of the negative electrode voltage is a beneficial method as it leads to faster process times while ensuring durable cell properties.