Lithium battery pole piece extrusion coating thick edge phenomenon and solution

News source:Johnson Eletek BatteryTime:2019/3/11 15:38:21

In the industrial production of lithium batteries, die extrusion coating has become the most widely used coating method due to its high precision, wide coating window and high reliability. As shown in Figure 1, the slurry is supplied by a precise feed system (such as a screw pump) into the internal cavity of the die, evenly distributed across the width of the coating, and finally the slurry is squeezed through the slit of the die, moving A coating is formed on the substrate. Due to the slurry fluid characteristics, the meniscus features as shown in Fig. 1 are easily formed at the starting point, the end point of the coating, and the both side edges. In the coating process, the thickness of the edge of the pole piece appears as a "thick edge" phenomenon.

According to the structural design of the battery and the corresponding process design, the lithium battery pole coating process can be divided into continuous coating and intermittent coating, as shown in Figure 2, in the continuous coating, thick edges that have an impact on battery performance and process. The problem is mainly at the edges of the two sides of the coating, and for gap coating, except for the edges on both sides, the thick edge of the coating may also be present at the beginning and end edges (head and tail) of the coating. This thick edge phenomenon is undesirable and can cause problems with the battery process and battery performance and consistency.