Requirements for compressed air in battery manufacturing process

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 compressed air meets the needs of high-precision manufacturing, a strict management and control system needs to be established in terms of cleanliness, stability and dryness.

1. Core quality indicator requirements

1. cleanliness control
   • Particulate matter restriction: The content of particulate matter with a diameter of>0.1μm in compressed air must be ≤1000 particles/m³ to avoid particulate pollution of electrode materials or electrolytes.
   • microbial control: For aseptic production scenarios such as lithium-ion batteries, the microbial load needs to be <1CFU/m³ to prevent microorganisms from degrading the membrane material.
2. Oil content control
   • The compressed air for battery manufacturing must meet the “oil-free” standard, that is, the total oil content is ≤0.003mg/m³, and is achieved by using an oil-free air compressor or a post-mounted catalytic oxidation device.
3. Water content management
   • The pressure dew point needs to be ≤-40℃, which is achieved through an adsorption dryer or membrane dryer to avoid moisture causing electrolyte deterioration or pole piece corrosion.

2. Application requirements for key process links

1. Pole piece manufacturing process
   • coating process: Compressed air is used to drive the slurry pumping system. It is necessary to ensure that pressure fluctuations are ≤±0.02MPa to avoid uneven coating thickness.
   • roller pressing process: The tension of the pole pieces is maintained stable through a pneumatic correction device. The compressed air needs to be controlled by a precision pressure regulating valve, and the pressure accuracy reaches 0.01MPa.
2. Battery cell assembly process
   • lamination process: To use compressed air to drive a robot to grab the pole piece, a vacuum generator needs to be equipped with a vacuum degree of ≥-80kPa to ensure that the positioning accuracy of the pole piece is ≤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 to prevent the introduction of impurities.
3. Formation and volume separation process
   • air tightness detection: Compressed air is used for battery case sealing test. The pressure must be stable at 0.5MPa±0.005MPa, and the test cycle is ≤5 seconds.
   • environmental control: The air conditioning system is driven by compressed air to maintain ISO 7 cleanliness in the workshop, and fluctuations in temperature and humidity are ≤±1℃/±5%RH.

3. System design and maintenance specifications

1. Pipe material selection
   • Pipelines and valves that come into contact with compressed air must be made of 316L stainless steel or PTFE coating to avoid metal ions from precipitating and polluting battery materials.
   • Pipe connections use bayonet joints to reduce welding points and reduce the risk of particulate matter falling off.
2. hydrodynamic design
   • The pipeline layout avoids blind pipes, and the dead corner length is ≤1 times the pipe diameter to ensure complete gas replacement.
   • Terminal filters are equipped with key gas points with a filtration accuracy of 0.01μm, and a pressure gauge is installed for real-time monitoring.
3. PM strategies
   • The air filter element is replaced every 1500 hours, and integrity testing is performed before and after replacement.
   • The regeneration cycle of the dryer is implemented in accordance with the equipment manual, and the accuracy of the dew point meter is regularly checked to ensure stable dew point.

4. Key management and control points for typical application scenarios

V. Quality traceability and continuous improvement

1. 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 clarify the root cause and formulate corrective measures.
2. annual quality review
   • The quality of the compressed air system is reviewed every year to analyze parameters such as filter life and dryer efficiency.
   • Optimize maintenance plans based on data trends, such as adjusting filter replacement cycles or dryer regeneration temperatures.

conclusion
Battery manufacturing companies need to establish a quality management system covering the entire chain of “production-transportation-use” of compressed air, and ensure that the quality of compressed air continues to meet battery manufacturing requirements through scientific design, rigorous maintenance and continuous monitoring. With the iterative upgrading of battery technology, companies should actively introduce technical means such as smart sensors and big data analysis to achieve real-time early warning and lean management of compressed air quality, and provide a solid guarantee for the quality and safety of battery products.