18650 battery bulk manufacturers explain the two process technologies of 18650 battery bulk winding and lamination

　　18650 battery bulk manufacturers explain the two process technologies of 18650 battery bulk winding and lamination. 18650 battery bulk winding and lamination technology is like twin brothers fighting, and the market determines life and death. The core manufacturing process of lithium-ion batteries is divided into lamination process and winding process, which are mainly distinguished by the assembly method of the pole pieces. In this article, 18650 battery bulk manufacturers will analyze the process and equipment characteristics of the two processes of winding and lamination.

　　18650 battery bulk manufacturers explain the two process technologies of 18650 battery bulk winding and lamination

　　With the widespread use of lithium batteries as power sources in mobile phones, digital products, laptops, drones, model aircraft, power tools, special and new energy vehicles, portable energy storage, medical equipment and other fields, the domestic 18650 battery bulk industry has developed rapidly. As an important part of 18650 battery bulk manufacturing, the lamination and winding process has attracted widespread attention from academia and business circles.

　　Winding process: For example, cylindrical batteries, this process is to stack the raw materials together in the order of negative electrode, separator, positive electrode, and separator, directly roll them into a cylindrical shape through the winding method, and then place them in a metal casing; because the internal structure is not stable Uniformity, the internal reaction degree and rate of the battery cell are uneven during charging and discharging; therefore, for thicker coiled batteries, there is a possibility of deformation after high-rate charging and discharging or after multiple cycles. Moreover, it can only be made into a rectangular parallelepiped battery.

　　18650 battery bulk winding equipment includes automatic unwinding of positive and negative electrode sheets and separators, automatic dust removal, automatic winding of positive and negative electrode sheets, pasting of termination tapes, automatic blanking of finished products, pre-pressure and weighing, and QR code pasting. In the winding process, after the pole piece separator is made into a battery core, the electrodes at the edges on both sides have a large curvature. During the charging and discharging process, they are easily deformed and twisted, which will lead to a decrease in the performance of the 18650 battery bulk and even a safety hazard. In addition, during the discharge process of the battery core, the current distribution on both sides is uneven, the voltage polarization is large, and the discharge voltage is unstable.

　　Lamination process: For example, soft-pack-shaped batteries rely on "stacking", such as "z"-shaped lamination. First, the positive and negative electrode raw materials are cut into rectangular pole pieces of the same size, and then stacked on the separator respectively. The separator " Z" shape passes through it, separating the two poles, and finally wrapped in aluminum plastic packaging.

　　The lamination process is cumbersome, mainly cutting the pole pieces and diaphragms into pieces. However, the pole piece slitting qualification rate is low, the quality (section, burrs, etc.) is difficult to maintain a high degree of consistency, and the alignment accuracy is insufficient.

　　Power lithium batteries can be divided into two types: coiled and laminated in terms of structure. According to the shell material, they can be divided into metal shells (steel, aluminum) and soft packs (aluminum plastic film). Domestic small factories mainly choose the soft package lamination process. It is estimated that the main starting point is to reduce equipment requirements and reduce capital investment. Nowadays, major domestic manufacturers (BYD, Lishen, ATL, etc.) have adopted the metal shell winding process, which requires a large investment in equipment, but can increase the degree of automation and thereby improve the consistency of lithium batteries.

　　Industry insiders generally believe that the lamination process can better leverage the advantages of large-scale lithium batteries, and it has advantages over winding in terms of safety, energy density, and process control. Therefore, for the field of power lithium batteries, the lamination process is the soft package There is no doubt about the long-term development trend of battery applications.

　　The reason why soft pack power battery companies choose to switch from lamination process to winding process

　　First, with the advantage of high energy density, the penetration rate of soft-pack batteries in the power market has increased rapidly. Data show that in the first quarter of 2018, soft-pack battery shipments were approximately 1.2GWh, accounting for 14% of shipments, a significant increase from the same period last year. Lamination efficiency cannot well meet the needs of battery companies.

　　Second, judging from the reasons for choosing to switch to the winding process, whether it is semi-automatic or fully automatic winding, it can be completed quickly and with high quality, and production control is relatively simple. At the same time, subsequent slitting is convenient and the pole piece qualification rate is high.

　　Third, the winding process is cheaper than the lamination process.

　　In general, the winding efficiency of 18650 battery bulk cells is high and the process is simple, but the quality of the battery cells is not as good as that of lamination. Although the lamination machine can improve efficiency through multiple stations, the overall cost is still high, the consistency of the cells is poor, and the competitiveness in the market is still weak, and it can only be used by a small number of people.

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