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01Risk of battery leakage

At present, car manufacturers stipulate that the service life of batteries is generally about 8 years. If the battery electrolyte leaks during use, it will affect the battery life and reduce the vehicle's cruising range. If the leakage is serious, the vehicle may catch fire due to factors such as high temperature, friction, or short circuit due to water wading during driving, resulting in serious safety accidents.

02How to detect battery leakage

There are currently several methods to detect whether there is battery leakage:

1. Pressure decay method: Traditional detection methods can only reach a maximum resolution of 1×10−4Pa·m3/s, which is not accurate enough;

2. VOC (Volatile Organic Compounds) detection method: Determine whether the battery is leaking by detecting battery leakage. The accuracy is low and it is easy to misjudge;

3. Hydrogen-nitrogen mixed gas concentration detection method: By measuring the concentration of hydrogen in the hydrogen-nitrogen mixed gas, it is converted into a leakage rate to determine whether there is a leak;

4. Helium mass spectrometry: By adding helium gas to detect whether the battery is leaking, the detection accuracy is high, but the cost is high and there are also defects;

5.RGA (Residual Gas Analysis/Residual Gas Analysis) method:Currently, the most reliable detection method has high detection accuracy and relatively low cost.

Disadvantages of the pressure decay method:1. The measurement of large leakage is inaccurate.After the electrolyte is injected into the battery, the internal space is very small, only a few tenths of a milliliter. Using direct pressure indirect or differential pressure finished product testing, products with large leaks cannot be identified; 2. The resolution is too low.The pressure decay method can only distinguish a maximum leakage rate of 1×10−4Pa·m3/s, which is far from meeting the battery detection accuracy requirements.

Disadvantages of VOC detection method:

1. Easily disturbed.Easily interfered by other volatile organic compound (VOC) gases, leading to wrong judgment; 2. Easy to misjudge.After battery VOC leaks, it will adhere to the fixture or pipeline, making cleaning very difficult and causing misjudgment; 3. Regular calibration is required.When you suspect that the readings are inaccurate, you need to use standard gas for calibration. The standard gas is a consumable; 4. Strict environmental requirements.The equipment has high requirements on the use environment and cannot be interfered by other VOC gases.

Disadvantages of the hydrogen-nitrogen mixed gas concentration detection method:

1. Easily disturbed.Easily interfered by hydrogen in the environment, leading to erroneous judgments;

2. The minimum resolution is too low.It can only resolve leakage rates of up to 5×10−8Pa·m3/s;

3. It takes a long time to start up after NG.If the product leaks greatly and the hydrogen-nitrogen mixed gas leaks out, the background concentration will be too high, and you need to wait for the spilled gas to dissipate before the next test can be performed;

4. Long-term use cost is high.40L of compressed hydrogen costs about 1,000 yuan. As long as it is tested, it requires long-term purchase.

Disadvantages of helium mass spectrometry detection:

① Helium must be added in advance, and the cost of using helium and helium mass spectrometers is very high; ② There are requirements for the storage environment of helium; ③ Helium recovery system needs to be invested, which is costly; ④ Helium is very light, and inside the battery, helium will float to the top of the case. There is no helium in the gap below the case, and if there is leakage in the lower part, it may not be detected.

03Principle overview

Hirays mass spectrometry leak detection system

The Hirays mass spectrometry leak detection system is a detection equipment based on the RGA principle of battery leakage.RGA is a residual gas analyzer that can quantitatively and qualitatively analyze the concentration and composition of residual gas in the vacuum chamber through mass spectrometry analysis.

RGA uses an ion source to ionize sample gas molecules under high vacuum conditions. After ionization, the molecules receive excessive energy and are further fragmented into various fragment ions and neutral particles of smaller mass. They acquire average kinetic energy with the same energy under the action of an accelerating electric field and enter the mass analyzer. The mass analyzer will simultaneously enter ions of different masses.Separation is carried out according to the mass-to-charge ratio m/e. The separated ions enter the ion detector in turn, and the amplified ion signals are collected. After computer processing, the organic components in the sample gas are analyzed.

By knowing in advance or measuring the characteristic mass number of the electrolyte according to the type of electrolyte, you can accurately determine the residual amount of electrolyte in the sample gas without being affected by the external environment, thereby determining whether the battery is leaking!Micron leaks can be realized!

After RGA ionizes the sample gas molecules, when the ion beam passes through the mass separator, only useful target ions are sent to the detector.

On the one hand, the anti-interference performance is greatly improved. On the other hand, as long as the mass number after ionization is between 1 and 100, RGA can achieve leakage detection by scanning the mass number.Whether it is helium, hydrogen, various electrolytes or other substances, it can be detected through RGA.

Advantages of battery leakage RGA method:

04Hirays mass spectrometry leak detection system

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