Separation capacity of lithium batteries.CR2032 button cell battery

　　The capacity division of batteries is achieved through the formation of a capacity division cabinet (which integrates the formation and capacity division functions into the same cabinet due to the same basic principle). The function of the formation of a capacity division cabinet is actually like a charger, but it can simultaneously charge and discharge a large number of batteries. When dividing the battery capacity, data from each detection point is obtained through computer management to analyze the size and internal resistance of these batteries, and determine the quality level of the battery. This process is called dividing the capacity.

　　After the first capacity division of the battery, it needs to be left standing for a period of time, usually no less than 15 days. During this period, some inherent quality problems will manifest, such as excessive self discharge, increased internal resistance, and so on. After the end of the soak period, conduct another testing and capacity division to eliminate those with quality issues that do not meet the level of capacity.

　　Another purpose of capacity division is to classify and group batteries, which is to select and combine monomers with the same internal resistance and capacity. When combined, only those with similar performance can form a battery pack. For example, power battery packs often require dozens to thousands of batteries to meet the energy needs of electric vehicles. Due to the complexity of the system, the behavior of the battery pack has its own uniqueness, and it is not just a simple addition and subtraction method for individual batteries to obtain the performance of the battery pack. Taking our common series and parallel battery packs as an example, ideally, the individual batteries in all battery packs should be completely consistent, but in reality, even single batteries produced in the same batch still have performance differences (including factors such as capacity and internal resistance). Although screening is carried out before the formation of the battery pack, it is still not possible to ensure 100% consistency in the performance of all batteries. In addition, due to the influence of the battery pack volume, there are also significant differences in the heat dissipation characteristics of different parts. Therefore, there is also a large temperature gradient in the temperature distribution of the battery pack. The above factors can lead to inconsistent degradation rates of the batteries in the battery pack during use, In this situation, on the one hand, it will cause a decrease in the usable capacity of the battery pack (limited by the minimum capacity of the series connected batteries in the battery pack). On the other hand, it may also lead to a decrease in the safety of the battery pack. Research shows that even if the cycle life of a single battery can reach over 1000 times, without the protection of a balanced device when composing a battery pack, the cycle life of the battery pack may be less than 200 times. Therefore, for a battery pack, the consistency of the single battery is a very important parameter.

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