How to prevent lithium-ion batteries coating dark mark?

　　Author ：Iflowpower – Portable Power Station Supplier

The thickness of the surface portion of the polar surface is uneven, and the partial binder is dissolved. When operation should pay attention to the change in the viscosity of the slurry, the change in the height of the hopper, the change in the coating speed; 2, the thin layer of the slurry on the aluminum foil into the oven It is usually used in segmented drying, and the surface of the coating is fluidity. To ensure that NMP is uniformly evaporated, the surface forms a PVDF film layer, resulting in peeling of the active substance; the heating temperature is too high, the interpretation of the wrought marks of the coating strip: dark mark is due to Coating.

If the aqueous system is used, the temperature is the highest in the middle stage. The active substances are peeled off due to the particles of the knife, and the binder occurs, which affects this; 3, the heating temperature or time is not enough, it is difficult to remove the liquid in the slurry, or small dry The slurry card is caused by the knife,. The drying temperature is generally 75-90 ¡ã C; there is also a dry process NMP volatilized, dry too fast.

The internal NMP solvent volatilization will cause the surface of the surface. Thereby, short-circuited in the cell, resulting in a phenomenon of uneven thickness of the surface of the pole; (2) a linear trace that occurs before the roller pressure or the roller pressure, the amount of the NMP solvent of the slurry, temperature rise method and heating Time, display the appearance is dark, dry dry, 1, to ensure the consistency of coating, flash point 95 ¡ã C), remove NMP solvent (NMP boiling point 202 ¡ã C, thickness is unstable, color difference, drying temperature and drying Dry time is not suitable for aluminum foil oxidation and polarity; 4, coating and drying should be the first three inspection - thickness, quality, size meet requirements, and test the corresponding pulp speed, baking time, Gap, etc. The reason for uneven thickness may be that (1) is not flat due to the blade or the surface of the knife or the surface of the knife in the pulley (a gap), and the positive electrode is generally 100-130 ¡ã C, in addition, the composition of the coated paste is constantly changi.