How to charge lithium-ion batteries quickly and safely?

The decay mechanism of lithium-ion batteries is huge. In this model, the author mainly includes two types; 1) the analysis of the appearance of the electrolyte on the negative electrode, the formation of Li2CO3 and (CH2OCO2Li) 2, and the formation of the SEI film on the negative electrode; 2) The metal Li is precipitated on the appearance of the negative electrode, which will deplete the active Li on the one hand, and on the other hand will also cause the active area of u200bu200bthe negative electrode to decrease. The electrochemical response at the electrode-electrolyte interface can be expressed by the Butlrt-Volmer equation, where as,int is the area of u200bu200bthe embedded response, ηint is the overpotential of the particle appearance, i0,int is the interchange current density, and the particle appearance The overpotential can be expressed by the following formula, where φs and φe are the electrode appearance and the potential of the electrolyte, Ueq and int are the equilibrium potential, and JLitotal is the total reverberation speed of the interface, including lithium insertion reverberation, interface sub-reverberation and negative electrode analysis. Lithium etc. Regarding the electrode interface secondary response, we can still recover the Butlrt-Volmer equation to express it. Since the interface secondary response is irreversible and the reduction analysis is dominant, the above equation 10 can also be rewritten as the same form as shown in the following equation. The process can also be expressed by the Butlrt-Volmer equation. The precipitation of metallic Li in the negative electrode is important because the negative electrode has a large overpotential. Therefore, the potential of the negative electrode to Li is lower than 0V, which leads to lithium precipitation in the negative electrode. The overpotential of the negative electrode lithium reverberation can be expressed by the following formula, so the process of using the lithium ion battery due to the continuous development of the SEI film and the loss of active Li caused by the negative electrode appearance lithium can be integrated by integrating the two secondary reverberation speeds. The method is obtained, as shown in the following formula. According to the above model and after performing the downgrade processing, the author imitated a 39Ah large-size soft pack battery. The battery was charged to 4.2V at a constant current rate of 2C, and then charged at a constant voltage until the current dropped to C/40. The battery is discharged at a constant rate of 1C until the current drops to 3.0V. The relationship between the battery capacity retention rate and the number of cycles during the cycle is shown in Figure a, and the voltage curve change during the discharge process is shown in Figure b. From the figure, we can probably see that this model mimics the decline of lithium-ion batteries in the process of reincarnation, and the error between the two is less than 1%. According to the model, the author clarified the origin of the capacity loss in the process of white reincarnation. From the figure, it can be seen that the important capacity loss in the process of reincarnation comes from the loss of active Li caused by the secondary reverberation. It will not begin to show lithium after the reincarnation process 300 times. . According to the battery cycle data of 5C rate charging, it can be seen that the battery has a linear decline pattern at the beginning, but after 60 cycles, the capacity decline will begin to accelerate. According to the model, it is explained that the capacity loss in the battery before the 60 cycles is important. Due to the loss of active Li caused by the secondary reverberation, the negative electrode lithium evolution began to appear after 60 times. The battery polarization environment near the barrier in the process of reincarnation of the battery mentioned above can be seen from the figure as the battery aging level increases, and the polarization of the battery is also obviously increasing. After 60 cycles of reincarnation, the negative electrode has begun to show negative The potential of, confessed that the lithium extraction began at this time, and the phenomenon of lithium extraction in new batteries following the aging inheritance is more serious, which causes the battery to begin to show the phenomenon of accelerated decline in capacity. From the above clarification, it is not ashamed that how to prevent lithium evolution during the fast charge process is the key to the accelerated life decline caused by fast charging, and the potential of the negative electrode is less than 0 (vsLi+/Li) is the primary cause of lithium precipitation in the negative electrode. Therefore, we can operate the above model to evaluate the differential charging mode by tracking the negative pole polarization potential in the differential charging mode. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. 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