application of film slitting machine in the field of new energy: lithium battery separator slitting process

Film slitting machine plays a key role in the field of new energy, especially in the production process of lithium battery separator. As one of the core components of the battery, the accuracy and quality of the slitting process of lithium battery separator directly affect the safety, energy density and cycle life of the battery. The following are the application and technical points of film slitting machine in lithium battery separator slitting process:

1. Characteristics and slitting challenges of lithium battery separators

• Material properties: The separator is usually made of polypropylene (PP), polyethylene (PE) or ceramic-coated multi-layer composites with a thickness of only 5-20μm, which requires high porosity, low thermal shrinkage and excellent mechanical strength.

• Slitting difficulties:

◦ Extremely thin and fragile: The material is fragile and prone to burrs, cracks, or edge delamination when slitting.

◦ High cleanliness requirements: The surface of the diaphragm should not be contaminated by dust, oil or metal particles.

◦ Tension control: Maintain constant tension to avoid tensile deformation or wrinkles.

◦ Dimensional accuracy: The width tolerance usually needs to be controlled within ±0.1mm.

2. The key technology of film slitting machine

In order to meet the high requirements of diaphragm slitting, the slitting machine needs to have the following core technologies:

(1) High-precision slitting system

• Tool selection: Diamond-coated or cemented carbide round knives are used to reduce burrs caused by tool wear.

• Laser slitting technology: Some high-end production lines use laser cutting to achieve contactless slitting and avoid mechanical stress (suitable for ceramic coated separators).

• On-line monitoring: Real-time detection of edge quality through CCD vision system and automatic deviation correction.

(2) Intelligent tension control

• Multi-stage closed-loop control: from unwinding to rewinding, multi-stage magnetic particle brake or servo motor is adopted, and the tension fluctuation is controlled within ±0.5N.

• Anti-wrinkle guide roller design: equipped with arc flattening roller or vacuum adsorption device to eliminate material stress.

(3) Clean environment guarantee

• Dust-free design: The slitter is equipped with an air purification system (such as HEPA filter), and the cleanliness of the working environment is more than 10,000 degrees.

• Static Elimination: Integrated ionic air bar prevents the diaphragm from adsorbing dust.

(4) Automation and digitalization

• Automatic tool change system: automatic switching according to the degree of tool wear to ensure cutting consistency.

• Data traceability: The slitting parameters (speed, tension, temperature, etc.) are recorded through the MES system to achieve process traceability.

3. The core process of the slitting process

1. Unwinding: The diaphragm mother roll is fixed by the inflatable shaft, and the tension is gradually released.

2. Pre-treatment: The cleaning roller removes surface impurities, and the static eliminator discharges.

3. Slitting: Slitting into the required width (such as 60mm, 120mm, etc.) according to the battery specifications.

4. Quality inspection: online detection of thickness, width and defects (such as pinholes, scratches).

5. Rewinding: Constant tension winding, surface wrapping protective film to prevent pollution.

4. Industry application cases

• Wet diaphragm slitting: Ultrasonic slitting is required to reduce thermal effects due to the thinner thickness (5-9 μm).

• Dry diaphragm slitting: higher requirements for tool wear resistance, regular calibration is required.

• Coated separator: Laser slitting avoids coating peeling, but is costly.

5. Future development trends

• Ultra-thin separator slitting: With the development of solid-state batteries, separators below 3μm put forward higher requirements for slitting machines.

• Intelligent upgrade: AI algorithm optimizes slitting parameters and reduces manual intervention.

• Green manufacturing: Reduce energy consumption and waste generation in the slitting process.

summary

The film slitting machine is a key equipment in the production of lithium battery separator, and its technical level directly affects the yield rate and battery performance of the separator. With the improvement of battery energy density and safety requirements in the new energy industry, the slitting process will continue to evolve in the direction of higher precision, lower damage and intelligence. Enterprises need to combine the material characteristics and the needs of the production line to choose the appropriate slitting technology solution.