What is the reason for the capacity decay of lithium batteries?

What is the reason for the capacity decay of lithium battery? 1. Lithium battery abuse. When the SOC of the lithium battery is below 120%, there is no obvious capacity loss; when the SOC is greater than 120%, lithium deposits begin to appear on the negative electrode, and due to the formation of a thicker SEI film, the impedance becomes larger and causes the active lithium If the overcharge continues, it will cause thermal runaway of the lithium battery. At an excessively high SOC, the decomposition rate of the electrolyte will become faster, and a thick deposition layer will be formed on the graphite negative electrode, and the lithium contained in the deposition layer will be precipitated. In addition, high-rate charging and discharging will also cause the capacity loss of the lithium battery. This is because the positive and negative electrodes will shrink and expand during the charging and discharging process. The greater the charge and discharge current, the more intense the contraction and expansion, and the greater the stress, which is positive and negative. Extreme particles are more likely to rupture or peel off from the current collector during rapid changes in volume, resulting in faster cycle decay. 2. The temperature factor must be mentioned is the use environment and conditions of the lithium battery damage its capacity. Temperature is definitely one of the key factors affecting the life of lithium batteries. Too high or too low temperatures will cause the reduction of active lithium ion content, the destruction of the electrode material structure, the dissolution of metal ions, and the serious capacity degradation. Conventional lithium battery operating temperature: -20℃~60℃, but generally lower than 0℃, the performance of lithium battery will decrease, and the discharge capacity will be reduced accordingly. Therefore, the operating temperature for the full performance of lithium battery is usually 0~40℃ . The temperature of lithium batteries required by some special environments is different, and some can even run normally in an environment of hundreds of degrees Celsius. 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 important reasons for the life degradation of lithium iron phosphate battery packs?