In the field of battery manufacturing, compressed air is a key process medium, and its quality directly affects battery performance, safety and production yield. In order to ensure that the compressed air meets the requirements of high-precision manufacturing, it is necessary to establish a strict control system from the aspects of cleanliness, stability and dryness.
1. core quality index requirements
- cleanliness control
- particulate Matter Restriction: The content of particles with diameter> 0.1μm in compressed air shall be ≤ 1000 particles/ m³ avoid particle contamination of electrode materials or electrolyte.
- microbial control: For aseptic production scenarios such as lithium-ion batteries, the microbial load needs to be <1CFU/ m³ to prevent microbial degradation of diaphragm materials.
- Oil content control
- compressed air for battery manufacturing must meet the “oil-free” standard, I.e. total oil content ≤ 0.003mg/ m³ it is realized by using oil-free air compressor or post catalytic oxidation device.
- Water content management
- pressure dew point shall be ≤ -40℃ it is realized by adsorption dryer or membrane dryer to avoid electrolyte deterioration or pole piece corrosion caused by moisture.
2. Application Requirements for Key Process Links
- pole piece manufacturing process
- coating process: Compressed air is used to drive the slurry pumping system, and it is necessary to ensure that the pressure fluctuation is ≤ ±0.02MPa avoid uneven coating thickness.
- rolling process: The pneumatic correction device is used to keep the tension of the pole piece stable. The compressed air needs to be controlled by a precision pressure regulating valve with a pressure accuracy of 0. 01MPa.
- Cell assembly process
- lamination process: Use compressed air to drive the manipulator to grab the pole piece, and a vacuum generator shall be configured, and the vacuum degree shall be ≥ -80kPa to ensure that the pole piece positioning accuracy ≤ 0.1mm.
- Liquid injection process: Compressed air is used for electrolyte transportation and needs to be equipped with a sterilization filter with a filtration accuracy of 0. 01μm prevent the introduction of impurities.
- Formation and volume division process
- air tightness detection: Compressed air is used for battery case sealing test, and the pressure should be stabilized at 0. 5MPa ± 0.005MPa detection period ≤ 5 seconds.
- Environmental Control: The air conditioning system is driven by compressed air to maintain the cleanliness of the workshop at ISO level 7, and the temperature and humidity fluctuation is ≤ ±1℃ /± 5% RH.
3. System Design and Maintenance Specification
- pipe Material Selection
- pipes and valves in contact with compressed air shall be made of 316L stainless steel or PTFE coating to avoid metal ion precipitation and pollution of battery materials.
- The pipe connection adopts ferrule type joint to reduce the welding point and the risk of particle shedding.
- Fluid Mechanics Design
- avoid blind pipes in the pipeline layout, and the length of dead corners shall be less than or equal to 1 times of pipe diameter to ensure complete gas replacement.
- The key gas point is equipped with a terminal filter with a filtration accuracy of 0. 01μm, And install a pressure gauge for real-time monitoring.
- Preventive Maintenance Strategy
- the filter element of the air filter is replaced every 1500 hours, and the integrity test is carried out before and after the replacement.
- The regeneration cycle of the dryer shall be in accordance with the equipment manual, and the accuracy of the dew point meter shall be checked regularly to ensure the stability of the dew point.
Control Points of 4. Typical Application Scenarios
| process link | compressed air quality requirements | control focus |
|---|---|---|
| coating process | cleanliness ISO level 5, oil content ≤ 0.001mg/ m³ | terminal filtration online sterilization |
| liquid injection process | cleanliness ISO level 6, water content ≤-60 ℃ dew point | adsorption Drying Periodic Integrity Test |
| formation process | cleanliness ISO class 7, microbial load <10CFU/ m³ | periodic environmental monitoring filter replacement |
5. quality traceability and continuous improvement
- electronic Batch Record
- compressed air quality data is incorporated into the electronic batch record system to achieve traceability of the production process.
- Abnormal data triggers the deviation investigation process to identify the root cause and develop corrective actions.
- Annual Quality Review
- annual quality review of the compressed air system to analyze parameters such as filter life and dryer efficiency.
- Optimize maintenance schedules based on data trends, such as adjusting filter replacement cycles or dryer regeneration temperatures.
Conclusion
battery manufacturers need to establish a quality management system covering the whole chain of “production-delivery-use” of compressed air, and ensure that the quality of compressed air continues to meet the requirements of battery manufacturing through scientific design, rigorous maintenance and continuous monitoring. With the iterative upgrade of battery technology, enterprises should actively introduce smart sensors, big data analysis and other technical means to achieve real-time warning and lean management of compressed air quality, and provide a solid guarantee for the quality and safety of battery products.
