Introduction About Lithium-Ion Cell Production Process

Lithium-ion cells are divided into two categories, one is the metal shell cell, a polymer lithium cell. Lithium-ion cell production process is divided into three major processes, one is the production of poles, the second is the production of the cell, the third is the battery assembly.

 

What are the main production processes of lithium cell?

Mixing (positive and negative active material + conductive agent + binder + dispersant) - Coating - Rolling - Slitting - welding lugs - Winding (or gasket) - Stick tape -Into the core shell -Welding -Sealing -Chemistry, etc.; The production process of the entire battery industry is more or less the same, the main difference is that the equipment is different or the battery products are different, such as polymer lithium cells are generally laminated, cylindrical winding, square winding and laminated coexist; Resulting in the cell in the winding process is not the same; the most important and most core technology in the mixing and coating, and the final formation‌.

 

The production process of lithium cell is relatively complex, the production process contains the electrode production of stirring and coating stage, the winding and liquid injection stage of the core synthesis, as well as the packaging and testing stage of the formation encapsulation, and the value share is about (35~40%):(30~35)%:(30~35)%. Understanding from the coating process, the differences mainly come from different equipment suppliers, imported/domestic ratio differences, etc., the process is basically the same, the value of the proportion of deviation but generally in line with the ratio.

 

Lithium cell production equipment corresponding to the front section of the process mainly includes vacuum mixer, coating machine, roller press, etc.; the middle section of the process mainly includes die-cutting machine, winding machine, stacking machine, liquid injection machine, etc.; the back section of the process includes the formation machine, separation and testing equipment, the process of warehousing and logistics automation. In addition, the production of cells also requires pack automation equipment.

 

Cell manufacturing process, the middle process is mainly to complete the molding of the core, the main process including film, pole winding, die-cutting, core winding molding and stacking molding, etc., is the current domestic equipment manufacturers to compete in a more competitive field, accounting for about 30% of the value of lithium cells production line.

 

Lithium cell-end process: the formation is the core part of the capacity separation

Cell back-end production process is mainly divided into four processes, formation, testing and packaging into the warehouse, accounting for about 35% of the value of the production line, formation and division as the main link in the back-end process, the activation of molded batteries for testing, due to the battery charging and discharging test cycle is long, so the value of equipment is the highest. formation process is the main role of the process The main function of the formation process is to charge and activate the cells after liquid injection, while the separation process is to test and grade the capacity and other electrical performance parameters of the cells after activation, formation and separation are performed by the formation machine and separation machine respectively, which are usually accomplished by the automated separation and formation system.

 

ZKbattery: Cylindrical lithium iron phosphate battery C33 15000mAh 3.2V power battery electric18650

 

 

The production and fabrication process of polymer lithium cells: 

Polymer lithium cells are thermally encapsulated, while metal shell cells are generally welded (laser welding). The reason why polymer lithium cells can be thermally encapsulated is that they use aluminum-plastic packaging film as a material.

 

Step 1- electrode slurry preparation 

Mainly to mix the electrode active material, binder, solvent, etc., and form a slurry after sufficient mixing and dispersion.

 

Step 2 - Coating 

The paste prepared in the first step is uniformly coated onto the collector (aluminum foil or copper foil, etc.) at the specified thickness and the solvent is dried.

 

Step 3 - Punching 

Punch the pole piece made in the previous step into the specified size and shape.

 

Step 4 - Stacking 

Assemble the positive and negative pole pieces and diaphragm together, and form the pole core after completing the gluing.

 

Step 5 - assembling polymer core 

The core produced in the previous step will be loaded into the pitted aluminum-plastic film, and complete the top sealing, side sealing, etc. (but also to leave a port for liquid injection, oh), the formation of the  package of the core is not injected with liquid.

 

Step 6 - Liquid injection 

Inject the specified amount of electrolyte into the interior of the polymer cell core.

 

Step 7 - Battery Sealing

The gas inside the cell is extracted in a vacuum environment and the sealing is completed.

 

Polymer lithium cell advantages.

1. Good safety performance, polymer lithium cell in the structure of the aluminum-plastic film packaging, in the event of safety hazards in the polymer cell at most will be puffed and cracked, unlike the steel shell aluminum shell battery cell will explode.

2. Light weight, polymer cells are 40% lighter than steel shell lithium batteries of the same capacity, and 20% lighter than aluminum shell batteries.

3. Large capacity, polymer lithium compare with the same size of the steel shell battery capacity is higher than 10-15%, higher than the aluminum shell battery 5-10%.

4. Small internal resistance, the internal resistance of polymer lithium is smaller than that of steel shell lithium batteries, and the internal resistance of domestic polymer cell can be achieved at a minimum of 35mΩ, which greatly reduces the self-consumption of the battery.

5. Flexible design, the shape of polymer lithium batteries can be customized according to customer needs, customized new cell models.

 

ZKbattery: Power 15C 16000mah high rate UAV plant protection aircraft model battery starting cell

 

Product model	ZK502040	ZK602040	ZK652040	ZK802040	ZK902040	ZK102040	ZK1174170S
voltage (V)	3.7V	3.7V	3.7V	3.7V	3.7V	3.7V	3.7V
Range of capacity(mAh)	350	400-450	500	650	700	800	1600
Current of charge	0.2A	0.2A	0.2A	0.2A	0.2A	0.2A	0.2A
Internal resistance	<200	<200	<200	<200	<200	<200	<200
Weight(g)	8.6g	9.5g	10.0g	11.4g	14.3g	15.2g	40g