What are the factors that affect the cycle life of lithium battery packs?

The charging and discharging cycle process of lithium battery pack is a complex physical and chemical reaction process, and its cycle life influence factors are various. The following is an analysis of the factors that affect the cycle life of lithium battery packs. 1. Design and manufacturing process In the battery design process, the choice of materials is the most important factor. Different materials have different performance characteristics, and there are also gaps in the performance of the batteries developed. The cycle performance of the positive and negative materials is good, and the cycle life of the battery will be long. Generally speaking, the capacity of the negative electrode is generally required to be excessive relative to that of the positive electrode during the design and assembly process. If it is not excessive, the negative electrode will precipitate lithium during the charging process, forming lithium dendrites, thereby affecting safety. There is too much excess of the negative electrode relative to the positive electrode, and the positive electrode may be excessively delithified, causing the structure to collapse. The type and amount of electrolyte also affect the battery life. The manufacturing process of lithium battery packs mainly includes: positive and negative electrode ingredients, coating, sheeting, winding, shelling, liquid injection, sealing, forming, etc. In the battery processing process, the requirements for each step of the process are very strict. Any process that is not well controlled may affect the battery cycle performance. 2. Lithium battery material aging and deterioration The process of charging and discharging cycle of lithium battery pack is the process of lithium ions deintercalation and movement back and forth between the positive and negative materials through the electrolyte. During the cycle of lithium battery packs, in addition to oxidation-reduction reactions at the positive and negative electrodes, there are also a large number of side reactions. If the side reactions of the lithium battery can be reduced to a low level, and the lithium ions can always smoothly go back and forth between the positive and negative materials through the electrolyte, the cycle life of the lithium battery can be increased. The nature of the positive and negative current collectors will also affect the capacity and cycle life of the battery. The commonly used current collector materials for the positive and negative electrodes of lithium battery packs are aluminum and copper, both of which are corrosive metal materials. The formation of a passive film after the current collector is corroded, poor adhesion, local corrosion (pitting) and general corrosion will 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. The charging and discharging system during the cycle. The use process of the lithium battery pack is the process of charging and discharging cycles, the size of the charging and discharging current, the selection of the charging and discharging cut-off voltage and the charging and discharging method adopted, and the cycle of the lithium battery. Life span also has a very important effect. Blindly increasing the working current of the battery, adding a new charge cut-off voltage, lowering the discharge cut-off voltage, etc. will degrade the performance of the lithium battery pack. Different electrochemical systems have different charge-discharge cut-off voltages. During the charging process of the lithium battery, when the charge cut-off voltage is exceeded, it is considered that an overcharge has occurred. When a lithium battery is overcharged, the excess lithium ions extracted from the positive electrode will be deposited or embedded on the negative electrode, and the deposited active lithium easily reacts with the solvent, releasing heat to increase the battery temperature. When the discharge voltage of the lithium battery is lower than the discharge cut-off voltage, overdischarge is formed. In the process of over-discharge, lithium ions will be excessively extracted from the negative electrode, and it will be more difficult to re-intercalate during the next charge. The discharge capacity and charge-discharge efficiency of lithium batteries are greatly reduced during the cycle after over-discharge. In addition, lithium batteries are extremely likely to fuse under high current conditions, and equipment components may also be damaged. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous article: What are the technical ways to improve the specific energy of the power ternary lithium battery?