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Li-Polymer Battery Airtightness Testing Solution

1. Why Perform Airtightness Testing on Li-Polymer Batteries?

Airtightness testers play a core role in the production and quality control of Li-Polymer (Li-Po) batteries. Their importance not only relates to product performance but also directly affects battery safety, reliability, and compliance.

Li-Polymer Battery Figure 1: Li-Polymer Battery Structure Diagram

Core Roles of Airtightness Testing

  • Ensure safety: prevent electrolyte leakage and ingress of external moisture, avoiding swelling, combustion risks
  • Improve quality: maintain stable battery capacity and longer lifespan, reduce after-sales issues
  • Control process: verify whether sealing processes like heat sealing and welding meet standards to improve yield
  • Meet high standards: comply with stringent sealing requirements for high-end applications like drones and medical devices

2. Comparison of Testing Methods

Comparison of Testing Methods

Method Pressure Range Applicable Scenarios Advantages
Negative Pressure Method -10 ~ -20 kPa Conventional Mass Production Fast, low cost
Positive Differential Pressure Method 5 ~ 15 kPa High precision requirements (e.g., power batteries) Accuracy up to 0.01 mL/min
Helium Mass Spectrometry Vacuum Environment Laboratory-level validation Detection limit 10⁻⁷ Pa·m³/s

3. Typical Testing Process Demonstration

Stage Specific Steps
Preprocessing Let the battery rest at 25±2℃ (temperature-controlled room)
Scan and bind serial number
Testing Phase Positive pressure mode: inflate → stabilize pressure for 5s → test for 10s
Judgement criteria: ΔP ≤ 3Pa (corresponding to 0.03 mL/min)
Real-time pressure curve monitoring; automatic OK/NG judgement
Post-processing Automatically sort NG items to helium retest station
Upload data to MES (generate CPK report)

4. Conclusion

Airtightness testing of Li-Polymer batteries is a critical step to ensure their safety and performance stability. By choosing appropriate testing methods and strictly following testing procedures, the sealing performance of batteries can be effectively guaranteed, improving product quality and market competitiveness.