The button cell was then charged using the CC-CV method. First, the cell was charged with a constant current of 0.5C until reaching the upper voltage limit of 4.2 V. The voltage was then held until the charging current reached the lower threshold of C/20. After resting for 2 h to ensure that the battery had reached the rest potential, the first EIS measurements at 100% SOC were conducted. Afterwards, the cell was discharged at C/10 for 1 h, followed by another rest period of 2 h and the next EIS measurements. This process was repeated until the potential reached the EODV, followed by the last EIS measurement at 0% SOC.