Lithium-ion battery charging and discharging cycle is the process of lithium-ion through the electrolyte in the positive and negative materials back and forth between the de-embedding, moving process. In the lithium-ion battery recycling process, in addition to positive and negative redox reaction occurs, there are still a large number of side reactions.
If the lithium-ion battery side effects can be reduced to a low level, so that lithium-ion through the electrolyte can always smoothly and from the anode and cathode material between the lithium-ion battery can make the cycle life can be increased, the lithium-ion battery can be used in solar powered portable generator.
Lithium ions from cathode to cathode must be covered by the carbon anode SEI film, SEI film directly affects the cycle life of the battery. Foreign scholars on the aging of the battery materials decline earlier, especially on the SEI membrane more in-depth study. The main research method is to analyze the stability and decay mechanism of battery materials by battery life test data and electrochemical characterization method.
The stability of the SEI film has a significant impact on the stability of the battery. SEI film instability is easy to precipitate lithium metal, will lead to rapid decline of negative active material to form a stable SEI membrane lithium battery can be stored in high temperature conditions for more than 4 years.
D.Aurbach and other disassembly cycle after the lithium cobalt oxide batteries, through SEM, XRD and other experiments on the positive and negative pieces of the analysis, the capacity decline is mainly due to negative SEI membrane sustained consumption of Li + and LiCoO2 and HF cathode LiF interface Membrane and other irreversible side effects. Pamadass et al. [10] established a capacity-degrading model by describing the process of lithium ion loss caused by the continuous growth of negative SEI film during charge-discharge cycles. Sankarasubramanian et al.
Developed a capacity decay model including the diffusion of solvent and the growth mechanism of SEI film, and obtained the linear relationship between the capacity degradation and SEI film thickness and battery aging time.
The results show that the discharge capacity of the battery decreases gradually, and the internal resistance and the thickness of the lithium ion battery increase gradually. The portable solar power generator need to use these batteries. The results show that after 200 cycles, many cracks appear on the surface of the positive electrode, and the average particle size decreases. The negative electrode shows that the SEI film becomes thick and the lithium and lithium compounds precipitate at the end of the cycle. The stress of LiCoO2 can be induced by the deintercalation and intercalation of Li-ion, and the final particle size of LiCoO2 is decreased under the effect of internal stress fatigue.
J.Vetter on the internal battery material with the charge and discharge cycle of the aging mechanism of an in-depth analysis of the electrode material crystal structure stability, active materials and electrolyte interface reaction and binder performance degradation and other factors will be on the battery Capacity and power performance, and the causes and effects of the aging of positive and negative poles are summarized.
For the negative electrode material, in addition to the deterioration of the contact resistance caused by the deterioration of the contact between the anode components due to the formation and growth of the SEI film, the main factors are: the solvent embedded in the C-pole to generate the gas causes the C particle to rupture, Resulting in deterioration of the contact between the particles of the active material, precipitation of lithium metal and electrolyte reaction accelerated aging.
No comments:
Post a Comment