What are the basic methods to solve the inconsistency of lithium batteries

The method to solve the problem of inconsistency of lithium batteries Lithium batteries cannot be made into a large one, so many small batteries have to be organized. Everyone works hard and cooperates sincerely, and it can also fly with electric cars. At this time, we have to face a problem, consistency. Under the existing processing capacity and technological level, there are three common ways to solve the consistency problem of lithium batteries. 1. Reasonable sorting Put cells with similar performance parameters in a battery pack and try their best to make the initial state of the cells consistent; the purpose of sorting is to select cells with similar parameters. The sorting method has been studied for many years, and it is mainly divided into two categories: static sorting and dynamic sorting. 2. Improve the thermal management level to provide a more suitable and more uniform working environment temperature for lithium batteries to prevent the initial inconsistency from further deterioration; the addition of a thermal management system can adjust the temperature difference of the entire battery pack to keep it in a smaller range in. Cells that generate more heat will still have a high temperature rise, but will not be separated from other cells, and there will be no obvious difference in degradation level. 3. Improve the overall monitoring and balance capabilities of the lithium battery management system, and strive to improve the inconsistencies that have occurred. In order to solve this problem, the battery management system BMS has designed a balancing function. What will happen to the inconsistency of lithium batteries? 1) Capacity loss, the battery pack is composed of single cells, and the capacity conforms to the barrel principle. The capacity of the worst cell determines the capacity of the entire battery pack. 2) Loss of life. It is very likely that the cell with the shortest life span is the cell with a small capacity. Small-capacity batteries are fully charged and discharged every time, and the output is too strong, which is likely to reach the focus of life first. When the battery cell's life ends all the time, a group of battery cells welded together will die. 3) The internal resistance increases, the same current flows through different internal resistances, and the cells with large internal resistance generate more heat. The battery temperature is too high, causing the deterioration rate to accelerate, and the internal resistance will further increase. Internal resistance and temperature rise form a pair of negative feedback, which accelerates the deterioration of high internal resistance cells. Why are most lithium batteries small? With high energy density, lithium batteries are often afraid to design large capacity. The energy density of lead-acid batteries is around 40Wh/kg, while lithium batteries have exceeded 150Wh/kg. With the increase in energy concentration, the requirements for safety are rising. First of all, it is very dangerous for lithium batteries that can only have an excessive amount of energy, and encounter an accident, causing thermal runaway, and a sharp reaction inside the battery. In a short time, too much energy is nowhere to be released, which is very dangerous. Especially when the development of safety technology and management and control capabilities is not sufficient, the capacity of each battery should be restrained. Secondly, once an accident occurs, the energy wrapped in the lithium battery shell will be inaccessible and powerless by firefighters and extinguishing agents. They can only isolate the scene in the event of an accident and allow the accident battery to react by itself until the energy burns out. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.