What will happen if the binder floats up during the production of lithium batteries?

What will happen if the binder floats up during the production of lithium batteries ?

The coating process is an important part of the electrode manufacturing process in the lithium battery manufacturing process, and it is the process of completing the transfer of the electrode slurry from the liquid state to the electrode solid active material. After the electrode slurry is prepared, it is coated by means of screw pump, filter, screen, etc., and then coated by extrusion coating head or transfer roller, and attached to the current collector. After the lithium-ion battery is dried in the oven, the liquid slurry solidifies on the surface of the current collector, and the bonding force is stronger.

However, in this manufacturing process, we sometimes have a situation where there is no obvious abnormality on the surface during the drying process of the oven, but sometimes it is found during the rolling process after painting. After the sheet passes through the roller, there will be blanking, foil leakage or abnormal blackening of the pressing roller. What's going on here?

This may not be due to the ratio of binder during electrode paste preparation, but may be caused by the binder floating to the surface during electrode coating and drying.

After the slurry coating is completed, the product needs to be inspected. The inspection items are generally the surface load of the pole piece, the thickness of the pole piece, peel strength, resistivity, etc., and the electrolyte penetration effect of the pole piece can also be evaluated. The floating of the binder will reduce the peel strength of the pole piece.

After the slurry preparation is completed, the active substances, conductive agents, binders and other substances in the qualified slurry are uniformly dispersed, but if the drying conditions are not set properly, the uniformly dispersed substances will be redistributed. In the pole piece peel strength test, surface enrichment and reduced binder content in contact with the foil are abnormal.

In the process of pole piece rolling, due to the uneven distribution of the binder, under the action of a large rolling force, the pole piece will adhere to the surface of the pressing roller and peel off from the metal foil, which affects the quality of the pole piece. Control is absolutely not allowed.

The degree of flotation of the adhesive varies from light to heavy. In severe cases, the peel strength of the pole piece is low. In the case of the lighter, there is no apparent problem with the surface of the pole piece, but the life of the lithium-ion battery is shortened during use. This is because the active material is easily separated from the foil during charging and discharging.