The preparation of electrode plates belongs to the pre production process of lithium batteries, which is the basic link that determines the capacity, internal resistance, and stability of the battery. It mainly includes processes such as homogenization, coating, rolling, cutting, and slicing, with high requirements for cleanliness and temperature and humidity control throughout the entire process.
The homogenization process involves adding positive and negative electrode active materials, conductive agents, binders, and solvents into a mixing equipment according to the formula ratio, and dispersing and stirring them to form a uniform and stable slurry. The viscosity, solid content, and dispersion uniformity of the slurry will directly affect the subsequent coating quality, and particle agglomeration and imbalanced ratio will cause uneven performance of the polarizer. Aluminum foil is often used as a current collector for positive electrode slurry, while negative electrode slurry is generally coated on the surface of copper foil.
The coating process uses a coating machine to evenly coat the slurry onto a continuous metal foil material, which is then sent to an oven for drying, removing the solvent, and forming a wide polar plate with an active substance coating. The consistency of coating thickness, blank space, and surface density is the core control indicator. Coating omissions, scratches, and thickness deviations can cause differences in the capacity of individual batteries.
After drying, the polarizer enters the rolling process and is compacted by the rolling equipment to increase the compaction density of the active material, thereby improving the energy density of the battery. The rolling pressure needs to match the material characteristics, and excessive pressure can easily cause coating cracking and current collector deformation; If the pressure is insufficient, the compaction density cannot meet the design standards. After the roller pressing is completed, the wide pole pieces are cut according to the product specifications into long pole pieces of the specified width, and then the pole ear structure is processed through die-cutting or laser cutting to complete the pole piece production.
The main defects of this process are burrs, powder loss, and wrinkles on the edge of the polarizer. During production, the size and appearance will be checked online to remove unqualified polarizer and avoid internal abnormalities caused by flowing into the assembly process.
