This article discusses the impact of coating on the performance consistency of lithium batteries.
The coating process is divided into three sections: the slurry feeding system, the coating system, and the pole piece drying system. The three-in-one system requires each system to maintain stability to ensure the consistency of the pole piece.
The slurry feeding system is to transfer the slurry after stirring to the storage tank, transfer it to the transition cylinder through a diaphragm pump, and then use a screw pump to stably output the slurry through the filter device and the iron removal device to the coating equipment for coating. Several points that need to be paid attention to in the slurry automatic feeding system are: preventing the slurry from stratifying in the storage tank, the slurry level in the transition cylinder, the stability of the screw pump, and the blockage of the filter tank should be cleaned in time. The following figure is a schematic diagram of a certain automatic feeding system
The main coating methods of lithium battery slurry are comma scraper type, transfer type, and slit extrusion type coating. The three coating methods have their own characteristics. The scraper type is mainly used under laboratory conditions, the transfer coating is mainly used in the production of 3C batteries, and the slit extrusion coating is mainly used in power batteries. The parameters that characterize the stability of the pole piece are mainly the pole piece surface density, thickness, and adhesion. In the coating system, the factors that affect the consistency of the pole piece mainly include the manufacturing accuracy of the coating head, the stability of the screw pump conveying slurry, the stability of the compressed gas, the speed stability, and the control of dynamic tension.
Scraper type
Transfer type
Slit extrusion type
The pole piece drying system is mainly composed of several ovens with different temperature distributions, the purpose of which is to dry the pole piece. Paying attention to the drying temperature setting is necessary in the drying system. If the temperature is too high during the coating process, it is easy to cause the pole piece to crack. If the temperature is low, the pole piece cannot be completely dried, which will cause inconsistent local polarization of the battery. In addition, attention should be paid to prevent the problem of adhesive floating.
Defect defects such as thick head and thin tail, thick edges on both sides, dot-shaped dark spots, rough surface, and exposed foil often occur in the coating process. The thickness of the head and tail can be adjusted by the switching time of the coating valve or the intermittent valve. The thick edge problem can be improved regarding slurry properties, coating gap adjustment, slurry flow rate, etc. The rough surface with uneven stripes can be improved by stabilizing the foil, reducing the speed, and adjusting the wind knife angle.
This article briefly describes some factors that affect the consistency of the electrode in the coating process. The solutions are not elaborated. I believe that after understanding the problems encountered in the coating process and understanding its principles, you can find the right solution to solve the coating problem. Welcome to leave a message for discussion.
ACEY's coating machines are widely used in major lithium battery factories. You are welcome to consult our coating machines.
