Causes of lithium battery expansion

　　I. Expansion of lithium battery: voltage is inconsistent

　　1. High self-discharge leads to low voltage. The high self-discharge of the cell reduces the operating voltage faster than other cells, and its operating voltage is so low that it can be removed based on the stored operating voltage

　　2, charging imbalance, low working voltage; When the battery is charging, lithium ions are not uniform due to circuit resistance or charging current in the test cabinet. The difference IN operating VOLTages measured FOR SHORT-TERM storage (12 hours) is small, but for long-term storage the difference is large. In this way, the low voltage has no product quality problems and can be charged according to the battery. The working voltage is stored for more than 24 hours after charging during the manufacturing process

　　2. Excessive internal resistance leads to expansion of lithium batteries

　　Due to the different detection equipment, the internal resistance is large

　　1. If the test accuracy is not enough, the shock group cannot be removed, and the resistance in the display information is too large, the principle of AC bridge method should be adopted in the test of the internal resistance instrument.

　　2, storage time is long, lithium battery storage time is too long, resulting in excessive capacity damage, internal passivation processing resistance increases. It can be processed according to the charging activity.

　　3. Internal resistance caused by abnormal heating. During the production process (welding, ultrasonic, etc.), the lithium-ion core will cause abnormal heat of the rechargeable battery, leading to thermal closure of the diaphragm and more serious internal resistance

　　Three, lithium battery expansion reason: charging

　　1, lithium battery charging expansion lithium battery charging, lithium battery will rise, but generally not more than, but overcharging will lead to lithium battery electrolyte dissolution, air pressure expansion, lithium battery rise

　　2. Increase production and processing; In general, abnormal conditions in the production process (such as short-circuit fault, overtemperature, etc.) will cause the electrolyte of lithium battery to overheat and lithium ion to rise

　　3. Expansion during cycling When the rechargeable battery is in the circulation system, the film thickness increases with the frequency of the circulation system, but the matrix does not increase after more than 50 weeks. Generally speaking, the normal growth rate is 0.30.6mm, and the aluminum case is more serious. This situation is a reflection of all ordinary rechargeable batteries. However, if the thickness of the shell is increased or the internal raw material is reduced, the rise after spot welding can be reduced

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