List the reasons that affect the cycle life of lithium battery packs

Exploring, what are the reasons that affect the cycle life of lithium battery packs? Lithium batteries are new batteries that have been approved by the public in recent years to extend battery life. However, after several cycles of charge and discharge cycles, the performance of battery capacity and other performance will decrease. . The faster the battery capacity is attenuated under the same conditions the battery quality is relatively poor. The cycle performance of lithium battery packs is an important indicator of their quality. Many standards for lithium battery packs have a cycle life.

Lithium battery pack charging and discharging cycle process is a complex physical and chemical reaction process, and its cycle life influencing factors are multifaceted. The following energy storage technology analyzes the factors affecting the cycle life of lithium battery packs.

1. Design and manufacturing process

The choice of materials is the most important factor in the battery design process. Different materials have different performance characteristics, and the performance of the battery developed is also different. The cycle performance of the positive and negative materials is matched, and the cycle life of the battery is long. Generally speaking, during the design and assembly process, the negative electrode capacity is generally required to be excessive with respect to the positive electrode. If the amount is not excessive, the negative electrode will precipitate lithium during the charging process to form lithium dendrites, thereby affecting safety. The negative electrode is excessively excessive with respect to the positive electrode, and the positive electrode may excessively de-decompose, causing the structure to collapse.

The type of electrolyte and the amount of liquid injected also affect battery life. The manufacturing process of the lithium battery pack mainly includes: positive and negative electrode batching, coating, tableting, winding, shelling, liquid injection, sealing, chemical formation and the like. In the battery production process, the process of each step is very strict. Any process that is not controlled can affect battery cycle performance.

2, Lithium battery material aging decline

The process of charging and discharging the lithium battery pack is a process in which lithium ions are deintercalated and moved back and forth between the positive and negative materials through the electrolyte. In the lithium battery pack cycle, in addition to the oxidation-reduction reaction of the positive and negative electrodes, there are a large number of side reactions. If the side reaction of the lithium ion battery can be reduced to a low level, and the lithium ion can smoothly flow back and forth between the positive and negative materials through the electrolyte, the cycle life of the lithium ion battery can be increased.

The nature of the positive and negative current collectors also affects the capacity and cycle life of the battery. The current collector materials commonly used for positive and negative electrodes of lithium battery packs are aluminum and copper, both of which are corrosive metal materials. The formation of a passivation film after the current collector is corroded, poor adhesion, local corrosion (pitting) and general corrosion all increase the internal resistance of the battery, resulting in a loss of capacity and a decrease in discharge efficiency. The adhesion and corrosion resistance can be enhanced by pretreatment methods such as acid-alkali etching and conductive coating.

3. Charge and discharge system during the cycle

The process of charging and discharging the lithium battery pack, the charging and discharging current, the selection of the charging and discharging cutoff voltage, and the charging and discharging system such as charging and discharging methods have a significant influence on the cycle life of the lithium ion battery. Blindly increasing the operating current of the battery, increasing the charge cut-off voltage, and lowering the discharge cut-off voltage will degrade the performance of the lithium battery pack.

The charge and discharge cutoff voltages of lithium ion batteries of different electrochemical systems are different. Overcharge is considered to occur when the charge-off voltage is exceeded during the charging process of the lithium-ion battery. When the lithium ion battery is overcharged, excess lithium ions extracted from the positive electrode are deposited or embedded on the negative electrode, and the deposited active lithium easily reacts with the solvent to release heat to raise the temperature of the battery. When the discharge voltage of the lithium battery is lower than the discharge cutoff voltage, overdischarge is formed.

During the overdischarge process, lithium ions will be excessively removed from the negative electrode, and it will be difficult to embed the next charge. The discharge capacity and charge and discharge efficiency of the lithium battery are greatly reduced during the cycle after overdischarge. In addition, lithium batteries are likely to blow under high current conditions, and equipment components may be damaged.

4, lithium battery use environment

The use environment of the lithium battery pack is also very important for its cycle life. Among them, the ambient temperature is a very important factor. Too low or too high an ambient temperature can affect the cycle life of a lithium battery.

Conventional lithium battery operating temperature: -20 ~ 60, but generally lower than 0 lithium battery performance will be reduced, the discharge capacity will be reduced accordingly, so the lithium battery performance of the full operating temperature, is usually 0 ~ 40. The temperature of lithium batteries required by some special environments is different. Also, pay attention to good ventilation, which is good for heat dissipation and keep the environment clean.

The charge-discharge cycle of a lithium-ion battery at high temperature is unstable. The high temperature causes the electrochemical polarization of the electrode of the battery to be intensified and the gas is generated, causing an inflation phenomenon, and at the same time, the charge transfer resistance is increased, and the ion transmission dynamic performance is lowered. The charging time of the constant voltage is increased at a low temperature, and the charging performance is also significantly deteriorated. Equipment that uses lithium-ion batteries may be subjected to vibration, shock, and collision conditions during transportation or normal operation. Some lithium batteries charge and discharge while communicating with the system and receive data information according to a certain frequency.

There are many factors that affect the cycle life of lithium battery packs. Lithium-ion batteries are becoming more and more widely used, and the demand for lithium batteries is higher in quantity and quality. The cycle life directly affects the use time and quality of lithium batteries, so it is necessary for manufacturers to study the influencing factors.

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