In recent years, lithium-ion batteries have gradually become the most important power source for electric vehicles, relying on the advantages of high energy ratio, high power ratio, long cycle life, and safety and reliability of the system.
Since the development time of lithium-ion battery technology is shorter than that of fuel technology, the current technology is not yet mature, and safety accidents such as spontaneous combustion and collision fires of lithium-ion batteries in electric vehicles continue to occur. There are many factors affecting the safety failure of the lithium-ion battery system, such as: excessive charging and discharging, short circuit, collision, high temperature, loose connection, etc. Among them, there are many safety accidents caused by loose connections, and the loose connections have difficulties such as large uncertainty and difficult diagnosis. Therefore, research on the connection technology of lithium-ion battery systems will improve the connection performance of lithium-ion battery systems, Process optimization and process management strengthening of manufacturing engineering are of great significance.
In the lithium-ion battery system, there are many processes involving connection technology. From the process point of view, there are mainly connections between three levels: the electrode-to-tab (Electrodes-to-Tab) at the unit cell level and the box seal. (CaseSealing), module-level cell-to-cell (Cell-to-Cell), battery pack-level module-to-module (Module-to-Module), as shown in Figure 1. Since the lithium-ion battery system is composed of many unit cells, modules, etc., it involves many connection technologies. Common connection techniques are: ultrasonic welding, resistance spot welding, laser welding, pulse TIG welding, mechanical connection, etc.
With the development of electric vehicles, the connection technology of lithium-ion battery systems has also made great progress. At the same time, the production of high-quality lithium-ion battery systems has gradually become the most critical issue in the field of battery manufacturing. In order to meet people’s demand for high-quality lithium-ion battery systems, it is necessary to conduct more in-depth technical research on connection technology. In addition to CT inspection and visual inspection of the connection status, CAE analysis can also be introduced to simulate the connection process, optimize process parameters, reduce the number of tests, and improve production efficiency and connection performance results. It is believed that with the continuous deepening of connection technology research, the process elements of various connection technologies are becoming clearer, the manufacturing process control is becoming more and more refined, and the quality of lithium-ion battery systems is more guaranteed, thus boosting electric vehicles to a new level. the height of.