Analysis of Lithium Battery Coating Technology

　　The positive electrode substrate of the lithium ion battery is aluminum foil, and the negative electrode substrate is copper foil. After coating, the positive pole piece roll and the negative pole piece roll are prepared for processing in the next step. The quality of the pole piece has basically determined some of the battery's performance, and the coating of the substrate is a very important part of the entire battery manufacturing process.

　　As we all know, the positive electrode substrate of lithium ion batteries is aluminum foil, and the negative electrode substrate is copper foil. After coating, the positive electrode sheet roll and the negative electrode sheet roll are prepared for the next step of processing. The quality of the pole piece is basically doomed to certain properties of the battery, and the coating of the substrate is a very important part of the entire battery manufacturing process! The coating method has been developed from the original dip coating and extrusion to the current state-of-the-art The double-sided coating at the same time is all to improve the coating quality and performance of the pole piece. Some domestic companies with strong economic strength, in order to manufacture reliable lithium-ion batteries, spend a lot of money to introduce expensive pole pieces from abroad. Coating machine.　　The general process of coating: the coated substrate (metal foil) is discharged from the unwinding device to the coating machine. The head and tail of the substrate are connected into a continuous belt at the splicing table and then sent to the tension adjustment device and automatic correction device by the pulling device. After adjusting the tension of the film path and the position of the film path, it enters the coating device. The pole piece slurry is applied in sections in the coating device according to the predetermined coating amount and blank length. During double-sided coating, the front coating and blank length are automatically tracked for coating. The coated wet pole piece is sent to the drying tunnel for drying, and the drying temperature is set according to the coating speed and coating thickness. The dried pole piece is wound after tension adjustment and automatic correction, for processing in the next step.　　The pole piece slurry coating is relatively thick, the coating amount is large, and the drying load is large. Currently, hot air impact drying technology is commonly used. The positive electrode substrate is aluminum foil, which has very active chemical properties and is easily oxidized. A dense oxide film is formed during the manufacturing process of aluminum foil, which prevents further oxidation of aluminum foil. Because the oxide film is thin, porous, soft, and has good adsorption properties, high temperature and humidity can destroy this oxide film. Speed up the oxidation reaction. At present, most of them are single-sided coating. When the first side is coated, the other side is completely exposed to hot air, while the hot air for coating (oil-based) drying should be around 130°C, such as hot air. If the moisture content is not effectively controlled, the oxidation of the aluminum foil will be intensified, which will affect the adhesion of the positive electrode material and the aluminum foil, and even cause it to fall off. American and Japanese coating machine manufacturers have developed double-sided simultaneous coating technology for single-layer coating machine energy efficiency and aluminum foil oxidation problems, which completely solves the problem of aluminum foil oxidation during coating, but the high price of double-sided simultaneous coating machines It is not acceptable for ordinary battery manufacturers.