Lithium battery separator longitudinal stretching production line

The main function of the longitudinal separator in lithium batteries is to separate the positive and negative electrodes of the battery, prevent short circuits caused by contact between the two poles. The micropores in the film can allow lithium ions to pass through, forming a charging and discharging circuit. The separator is a key core material in lithium batteries and a high value-added material with high technological barriers. Its performance determines the interface structure, internal resistance, battery capacity, lifespan, and safety performance of the battery.

In the structure of lithium batteries, the separator is one of the key inner components. The performance of the separator determines the interface structure, internal resistance, and other characteristics of the battery, directly affecting its capacity, cycling, and safety performance. An excellent separator plays an important role in improving the overall performance of the battery. The colloquial description of a separator is a porous plastic film, which is the highest technological barrier and high value-added material in lithium battery materials, accounting for about 20% -30% of the cost of lithium batteries.

Jinweier Machinery specializes in manufacturing PP/PE lithium battery separator dry single pull extrusion production lines. This production line is equipped with our company's MDO (unidirectional stretching) unit, which can achieve stable and uniform stretching of products, uniform pores, and greatly reduce the rate of defective products.

The lithium battery separator production line is divided into: dry unidirectional stretching production line; Dry bidirectional stretching production line; Wet extraction biaxial stretching production line.

Dry unidirectional stretching production line: The dry unidirectional stretching process is a method of producing hard elastic fibers, using PP or PE as the main raw material, mixed with various grades of auxiliary materials, and thoroughly stirred to prepare low crystallinity high orientation polypropylene or polyethylene films, and then high-temperature annealing to obtain high crystallinity oriented films. This type of film is first stretched at low temperatures to form micro defects, and then pulled open at high temperatures to form micropores. In terms of equipment, after extrusion molding by casting method, the multi-layer composite is processed by a laminating machine and subjected to unidirectional stretching. Then, the stretched multi-layer diaphragm is layered and cut by a layering machine and a slitting machine to produce unidirectional stretched lithium battery diaphragms. The Jinweier lithium battery dry pull production line is equipped with high-precision testing instruments and adopts a production process jointly developed with famous scientific research institutions in China. The main production thickness is 16 μ M to 40 μ Different specifications of lithium-ion battery separators. Application scope: Large lithium-ion power batteries (electric vehicles, electric motorcycles, electric tools, large energy storage equipment, military large batteries)

Dry biaxial stretching production line: the dry biaxial stretching process is a process with independent intellectual property rights developed by the Institute of Chemistry, Chinese Academy of Sciences in the early 1990s. Using PP as the main raw material, adding nucleating agents to polypropylene β Crystal type improver, utilizing the density difference between different phases of polypropylene, undergoes crystal type transformation during stretching to form micropores, and is used to produce single-layer PP membrane battery isolation films. In terms of equipment, after extrusion molding by casting method, bi-directional stretching is wound and slitted to produce bi-directional stretching lithium battery separators. Jinwei Lithium Battery Diaphragm Equipment is equipped with high-precision testing instruments and adopts a production process jointly developed with Chinese research institutions, mainly producing a thickness of 12 μ M to 40 μ Different specifications of double pull lithium-ion battery separators. At present, more than one-third of China's production capacity uses dry double pulling technology, and the products occupy a large proportion in the mid to low end market

Wet biaxial stretching production line: The wet process uses PE as the main raw material to mix liquid hydrocarbons or some small molecule substances with polyolefin resin and stir them thoroughly. After heating and melting, a uniform mixture is formed, and then the temperature is lowered for phase separation to press the membrane. The membrane is then heated to a temperature close to the melting point, subjected to biaxial stretching to align the molecular chains, and finally kept warm for a certain period of time. Residual solvents are washed off with volatile substances to prepare interconnected microporous membrane materials. In terms of equipment, the wet bi-directional stretching lithium battery separator is produced by extrusion molding through casting method, followed by extraction process to form pores, and then longitudinal and transverse stretching to roll and cut. The Jinweier wet double pull lithium battery separator line is equipped with high-precision testing instruments and adopts a production process jointly developed with Chinese research institutions, mainly producing a thickness of 8 μ M to 25 μ Different specifications of lithium-ion battery separators. Application scope: High performance lithium-ion batteries, etc.

 
                                                               （Dry pull lithium battery separator and electron microscopy image）

Product features: Lithium ion battery separator is a polymer functional material with nanoscale micropores. Rechargeable lithium-ion batteries have the characteristics of high specific energy, long cycle life, no memory effect, and are safe, reliable, and able to charge and discharge quickly. It meets the great development needs of energy and environmental protection in various countries today, and its usage in various industries is rapidly increasing.

1. Good uniformity in thickness and uniform distribution of micropores, which is conducive to the consistency of lithium-ion batteries;

2. Low porosity, good breathability, strong liquid retention ability, and low internal resistance of the battery;

3. High temperature resistance, no lateral thermal shrinkage, high film breaking temperature, and good safety performance;

4. High tensile strength and good mechanical properties;

5. The specifications of the production line are usually between 1000-2400mm in width, and the specific specifications are determined by the production process and can be customized.

Main uses of the product: various system power lithium-ion batteries for electric vehicles, electric motorcycles, electric bicycles, electric tools, large energy storage lithium-ion batteries, as well as various digital lithium-ion batteries.

Lithium battery separator dry pull production line parameters (please consult sales engineer for details)