When designing the manufacturing process of the power battery system (Pack for short), not only the safety and performance requirements of Pack products must be met, but also the manufacturing requirements such as safety and cost in production must be met. In order to facilitate the control of the production process, general manufacturers divide the production of Pack into six parts: module assembly, wiring harness production, structural parts production, BMS production, high-voltage control box assembly, and battery box assembly. In the actual production process, Pack will conduct an EOL test before going offline or leaving the factory to ensure the safety and performance of the Pack on the client side. This constitutes the complete production link of Pack, as shown in Figure 9-7.
In the power lithium battery industry, according to the company’s scale and process route, each company has different production links. Some only do part of the production process, and some only do another part of the production process. Even if the same part, the production process is different. of. From the perspective of long-term planning and cost, all production by itself is not conducive to the rational use of resources and the reduction of product costs. This chapter focuses on module assembly, pack assembly, key processes and EOL testing in the electric vehicle industry, and then analyzes the safety and process manufacturing technologies in the production of modules and packs.
A module generally refers to a battery cell assembly formed by connecting single cells in series and parallel, isolating and fixing the structure of the module, and then adding a battery unit protection control board (BMU). Cell manufacturers generally divide the cells into cylindrical, square, soft pack and special-shaped cells according to their shape. In the design of modules and packs, they generally do not use special-shaped cells. The popular names of the modules corresponding to the batteries are cylindrical, square, and soft-packed modules.
Although the country and the industry are vigorously promoting standardization, the current battery cell specifications are still relatively large, even cylindrical cells have a variety of specifications, resulting in very large differences in module design, structure, and technology. The following are mainly three types of modules. The structure and process flow are explained separately.
Meet the requirements of the entire vehicle. In order to ensure the consistency of the electrical performance of the modules, strict requirements must be imposed on the incoming materials of the batteries. Cell manufacturers generally group the cells according to their voltage, internal resistance, and capacity specifications before shipment, but the final requirements of cell manufacturers and pack manufacturers are different, considering the manufacturing process, cost, cell performance, etc. Factors, Pack manufacturers generally re-sort the cells according to their own standards.
Cell sorting needs to consider the issue of sorting standards. A reasonable standard will reduce the remaining idle cells, improve production efficiency, and reduce production costs. In the actual production process, it is also necessary to check the appearance of the battery core, such as checking whether the battery core has defective products such as insulation film damage, insulation film warping, battery leakage, and positive and negative end surface stains.