Capacity fade characteristics of nickel-based lithium-ion secondary battery after calendar deterioration at 80 °C

In this study, we evaluated the calendar deterioration behavior of nickel-based lithium-ion secondary batteries by storing them at 80 degrees C for different durations. The results indicate that the battery capacity decreased with the increasing number of storage days in a high-temperature environment. From the differential capacity curves, we found that the change in the overvoltage, which was caused by the electrode reaction, that appeared at approximately 4.2 V was most significant. To analyze this phenomenon, electrochemical impedance spectroscopy of the deteriorated battery was measured at 4.2 V, and it was confirmed that the cathode-based resistance of the battery increased significantly at this potential. Furthermore, post-mortem analysis revealed that the cathode active material of the tested batteries clearly deteriorated; however, no significant change in the active material in the anode was observed. Therefore, it is considered that the cathode materials of nickel-based lithium-ion secondary batteries deteriorate by storing at 80 degrees C, thereby resulting in reduced battery capacity and increased cathode component resistance after storing at high temperatures.

Automated summary

The study showed that storing nickel-based lithium-ion secondary batteries at 80 degrees C led to decreased battery capacity over time, primarily due to significant overvoltage changes at approximately 4.2 V. Additionally, post-mortem analysis revealed clear deterioration of the cathode active material in the tested batteries, while no significant changes were observed in the anode active material.