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Analysis of Influencing Factors on Cycle Life of Lithium Ion Battery
2021-07-22

With the development of science and technology and the maturity of technology, the application of lithium ion battery is more and more extensive. Lithium-ion batteries have many advantages, such as high cell voltage, light weight and environmental friendliness. However, after several cycles of charge and discharge, the battery capacity and other performances will decrease. Under the same conditions, the faster the battery capacity decays, the worse the battery quality is. Cyclic performance of lithium-ion battery is an important index to measure its quality, and many standards about lithium-ion battery include cycle life.
 
The charge and discharge cycle process of lithium ion battery is a complex physical and chemical reaction process, and its cycle life is influenced by many factors. On the one hand, it is related to the characteristics of the battery itself, such as design, manufacturing process and material performance degradation; On the other hand, it is related to the external influence of the battery during use, such as the use environment and charging and discharging system. The factors affecting the cycle life of lithium-ion batteries are analyzed below.
 
Introduction to the structure and principle of lithium ion battery
 
Lithium-ion battery is mainly composed of positive and negative materials, electrolyte, separator, current collector and battery shell. The positive and negative materials are composed of two different lithium ion intercalation compounds. When charging, lithium ions are deintercalated from the positive electrode and intercalated into the negative electrode through electrolyte and diaphragm, while when discharging, the opposite is true. In the first charge and discharge process of lithium ion battery, a passivation film can be formed on the phase interface between negative electrode and electrolyte. It acts as a diaphragm between the electrode and electrolyte, which is an electronic insulator but an excellent conductor of lithium ions. Lithium ions can be freely inserted and removed through the passivation layer and have the characteristics of solid electrolyte. Therefore, this passivation film is called "solid electrolyte interface" (SEI film for short).