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01Risk of battery leakage

Currently, 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, factors such as high temperature, friction, or water-related short circuits may cause car fires during driving, causing serious safety accidents.

02How to detect battery leakage

To detect whether there is a battery leak, there are currently several methods:

1. Pressure attenuation method: The traditional detection method can only reach the highest resolution of 1×10−4Pa·m3/s, and the accuracy is not enough;

2. VOC (Volatile Organic Compound) detection method: Determine whether the battery is leaking by detecting battery leakage, low accuracy and easy misjudgment;

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

4. Helium mass spectrometry: Detect battery leakage by adding helium gas. The detection accuracy is high, but the cost is high and there are also defects;

5.RGA (Residual Gas Analysis/Residual Gas Analysis) method: The most reliable detection method at present, with high detection accuracy and relatively low cost.

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

Defects of VOC detection method:

1. Easy to be interfered. It is easy to be interfered by other volatile organic compounds (VOC) gases, leading to wrong judgments; 2. Easy to misjudge. After the battery VOC leaks, it will adhere to the fixture or pipeline, making it very difficult to clean.Cause misjudgment; 3. Regular calibration is required.When it is suspected that the reading is inaccurate, standard gas is required for calibration, and the standard gas is a consumable;4. The equipment has strict environmental requirements and cannot be interfered by other VOC gases.

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

1. Easily interfered. Easily interfered by hydrogen in the environment, leading to wrong judgment;

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

3. The startup time after NG is long. 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 conducted;

4. The cost of long-term use is high. 40L of compressed hydrogen costs about 1,000 yuan. As long as it is tested, it needs to be purchased for a long time.

Defects 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 helium will float to the top of the case inside the battery. If there is no helium in the gap below the case, any leakage in the lower part may not be detected.

03Principle Overview

Hairus mass spectrometry leak detection system

Hairus mass spectrometry leak detection system is a detection equipment based on the principle of battery leakage RGA. RGA is a residual gas analyzer, which 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 a variety of 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 proceed.Enter the mass analyzer, which will separate the ions of different masses into it at the same time.The separated ions enter the ion detector in turn, collect and amplify the ion signals, and analyze the organic components in the sample gas through computer processing.

Knowing or measuring the characteristic mass number in advance according to the type of electrolyte, the residual amount of electrolyte in the sample gas can be accurately determined without being affected by the external environment, thereby determining whether the battery is leaking! Micron-level leaks can be achieved!

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

Advantages of battery leakage RGA method:

04Hairus mass spectrometry leak detection system

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