Capacity degradation analysis of 18650-type NCA lithium-ion battery under different working conditions

The capacity degradation characteristics of 18650 NCA lithium battery under different working conditions were investigated. Experiments were carried out at 45℃, and the direct effects of charge-discharge ratio and cut-off voltage on capacity degradation were analyzed. The results show that when the charge-discharge ratio is 2C, the capacity degradation rate is significantly higher than 1C and 1.5C. The degradation of battery capacity is more obvious in high cut-off voltage and high temperature environment. Through XRD and XPS characterization, it was found that high temperature resulted in the formation of lithium dendrites and the destruction of material structure, which affected the crystal state and chemical composition of the battery surface. The comprehensive analysis shows that the charge-discharge ratio and cut-off voltage are the key factors affecting the capacity degradation of 18650 NCA lithium battery. Optimizing these conditions can effectively delay the capacity decline and improve the service life and stability of the battery.