A low air intercalation battery cell bulging gas vacuum puncture sampling device and method

Abstract

The application provides a low-air-doped battery bulging gas vacuum puncture sampling device and method, relates to the technical field of battery gas production detection, and the device comprises a vacuum sealing bag, a flange, a sealing rubber plug, a portable vacuum sealing machine and a sterile sampling syringe; the vacuum sealing bag wraps the measured bulging battery, an elastic silica gel sealing rubber plug is fixedly embedded in the top opening through the flange; the portable vacuum sealing machine is used for vacuumizing and heat-sealing the bag body, so that the battery is in a vacuum closed environment; the sterile sampling syringe sequentially punctures the sealing rubber plug and the battery shell, and extracts the original bulging gas; the method comprises the steps of pretreatment, bagging positioning, vacuumizing and sealing, closed puncture sampling and sample storage; the application isolates air from the source by whole battery vacuum pre-packaging, simultaneously has the advantages of extreme light weight, full-scene portability, quick operation and low cost, and is widely applicable to accurate sampling of bulging gas in battery research and development, failure analysis and safety detection.

Description

Technical Field

[0001] This invention relates to the fields of battery gas generation detection, gas composition analysis and sampling technology, and more specifically, to a vacuum puncture sampling device and method for bulging gas in low-air-doped battery cells. Background Technology

[0002] During various reliability tests and operating conditions, the internal electrolyte of a battery undergoes decomposition reactions. Simultaneously, side reactions occur between the electrode materials and the electrolyte, continuously generating a mixture of gases such as hydrogen, carbon dioxide, methane, and carbon monoxide, causing bulging and deformation of the battery casing. The composition, content, and rate of gas generation are key parameters for determining battery failure mechanisms, optimizing electrolyte formulations, improving battery packaging processes, and identifying potential safety hazards. Therefore, accurate and impurity-free gas sampling is the prerequisite and foundation for battery gas generation analysis.

[0003] Currently, the most common method for sampling gas from bulging batteries in the industry is direct puncture sampling, which involves directly puncturing the bulging battery casing with a needle in the air environment to collect the gas. This method has a significant detection error. During the puncture process, outside air quickly enters the battery through the puncture gap. At the same time, air remaining on the battery surface and inside the sampling needle before sampling will be directly mixed into the gas to be tested. This causes air components to seriously interfere with the test results, making it impossible to accurately distinguish between the battery's original generated gas and air impurities. Trace characteristic gas components are easily masked by air, significantly reducing the accuracy of gas composition analysis.

[0004] Existing technologies capable of closed-loop sampling rely on large, fixed vacuum chambers, integrated vacuum tubing, specialized sampling platforms, and fixtures. These devices are bulky, heavy, and difficult to transport, lacking portability. They can only be fixedly installed in dedicated laboratory workstations and cannot be adapted to lightweight, mobile sampling scenarios such as outdoor testing, production line sampling, and multi-site rotation testing. Furthermore, these specialized devices have extremely high purchase and maintenance costs, complex operating procedures, require professional personnel for debugging and operation, and have long preparation cycles for each sampling. They cannot meet the batch, rapid, and high-frequency sampling needs in battery R&D. Moreover, the fixed chamber specifications make it difficult to adapt to bulging batteries of different sizes and degrees of deformation, resulting in extremely poor versatility.

[0005] In response to the core shortcomings of existing technologies, such as severe air impurities, heavy equipment, inability to move samples, complex operation, high cost, poor versatility, and inability to perform rapid batch sampling, this invention proposes a vacuum puncture sampling device and method for low-air-impurity battery cell bulging gas. Summary of the Invention

[0006] The present invention aims to solve the technical problems mentioned in the background art and provide a vacuum puncture sampling device and method for low air doping cell bulging gas.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a vacuum puncture sampling device for low-air-doped battery cell bulging gas, comprising: A vacuum-sealed bag is used to wrap the bulging battery to be tested, and the top of the vacuum-sealed bag has an opening; A flange is provided at the opening and is sealed and fixedly connected to the vacuum sealing bag; A sealing plug is embedded and fixed inside the flange; A portable vacuum sealing machine is used to vacuum the vacuum-sealed bag and heat-seal the bag opening. A sterile sampling syringe is used to sequentially puncture the sealing rubber plug and the casing of the bulging battery to be tested in order to extract the gas inside the battery.

[0008] Furthermore, the vacuum-sealed bag is made of any one of PE, PA, PET, or aluminum-plastic composite materials.

[0009] Furthermore, the sealing plug is made of elastic silicone.

[0010] Furthermore, the flange and the vacuum-sealed bag are seamlessly bonded together through a hot-melt sealing process.

[0011] Furthermore, the vacuum-sealed bag has an integrated bag structure and a pre-reserved sealing edge for heat sealing by the portable vacuum sealer.

[0012] Furthermore, the thickness of the sealing plug is 3mm to 8mm.

[0013] Furthermore, the sterile sampling syringe is an airtight micro-sampling syringe, and its needle is a thin-walled sterile puncture needle.

[0014] A method for vacuum puncture sampling of bulging gas in a low-air-doped battery cell, using the aforementioned apparatus, includes the following steps: S1. Pre-sampling treatment: Check the airtightness of the vacuum sealing bag and sealing plug to ensure there is no damage or leakage; perform vacuum pre-treatment on the sterile sampling syringe to remove residual air inside and set aside for later use; select a vacuum sealing bag of the corresponding specification to fit the size of the bulging battery to be tested. S2. Battery vacuum sealing: Place the bulging battery to be tested into the vacuum sealing bag smoothly, and adjust the battery position so that the bulging area of ​​the battery is aligned with the sealing plug at the top of the vacuum sealing bag to ensure accurate alignment for subsequent puncture sampling; place the opening of the vacuum sealing bag flat into the sealing groove of the portable vacuum sealing machine. S3. Vacuum sealing and molding: Start the portable vacuum sealer to remove all the air inside the vacuum sealing bag. After the bag is completely attached to the outer surface of the battery and a vacuum negative pressure environment is formed inside, start the hot-press sealing program to perform high-temperature hot-melt sealing on the bag opening, so that the bulging battery to be tested is completely in a vacuum-sealed airless environment. Let it stand for 1-3 minutes to ensure that the negative pressure of the bag is stable and the seal is reliable. S4. Closed-loop puncture sampling: Hold the pre-treated sterile sampling syringe and vertically pierce the sealing plug at the top of the vacuum-sealed bag with the needle. After piercing the sealing plug, accurately aim at the bulging area of ​​the battery and slowly puncture the battery casing to connect the inner cavity of the syringe with the gas-generating chamber inside the battery. Let it stand for 1-2 minutes until the gas pressure inside the battery stabilizes, then pull the syringe plunger at a uniform speed to quantitatively extract the original bulging gas inside the battery. S5. Sampling Completion and Sample Sealing: After gas extraction is completed, quickly pull out the syringe needle. The sealing rubber stopper will automatically rebound and close due to its own elasticity, restoring the vacuum sealing bag to a sealed state, with no gas leakage and no air infiltration. Seal the syringe needle containing the gas to be tested, mark the sample information, and complete the single sampling operation. The sample is then directly sent to the gas chromatography-mass spectrometry detection equipment for component analysis.

[0015] The beneficial effects of this invention are as follows: This invention provides a vacuum puncture sampling device and method for low-air-doped battery cell bulging gas. First, the entire bulging battery is placed inside a vacuum bag for complete vacuum sealing, thoroughly removing all air from the battery surface and sampling area. Puncture sampling is performed entirely in a vacuum-sealed environment, preventing external air from mixing with the gas to be tested. This completely solves the problem of severe air doping in traditional exposed sampling, effectively ensuring that the sampled gas is the original production gas of the battery, and significantly improving the accuracy of gas composition analysis. This invention completely overturns the traditional heavy-duty fixed sampling equipment. The design concept is that the entire device consists only of lightweight consumables and small handheld devices such as vacuum bags, handheld sealing machines, and syringes. It is compact, extremely lightweight, easily portable, requires no dedicated installation station, and requires no complex debugging. It is suitable for sampling needs in all scenarios, including fixed sampling in laboratories, batch sampling on production lines, outdoor testing, and remote testing. It completely solves the industry pain points of traditional equipment being immobile, space-constrained, and unable to operate outdoors. It is suitable for high-frequency, multi-scenario, and rapid batch sampling of batteries. This invention can use vacuum sealing bags of different materials and specifications to adapt to various applications. It supports all types of batteries, including cylindrical, prismatic, and pouch cells, and is compatible with batteries of varying degrees and sizes of swelling. There are no equipment compatibility limitations, and its application covers the entire process of battery R&D, aging testing, and failure analysis. The overall sampling process is simple and quick, requiring no specialized technical skills. A single person can complete the entire process of encapsulation, sealing, puncture, and sampling within 10 minutes using a handheld device, significantly improving sampling efficiency. All core components are standard lightweight consumables and universal handheld devices, resulting in extremely low purchase, use, and maintenance costs. Consumables can be single-use to prevent cross-contamination or reused. It is designed for large-scale, routine sampling and testing in research institutions, small and medium-sized laboratories, and enterprise production lines, making it highly practical and applicable. Utilizing a flexible, self-healing sealing plug design, it automatically seals after puncture, preventing gas leakage and air backflow during sampling. This ensures a stable sampling environment, high sample integrity, and good repeatability. It is suitable for various electrochemical batteries, including cylindrical, prismatic, and pouch batteries, and is ideal for sampling after gas production during charge-discharge testing, aging testing, and overcharge / abuse testing, providing a gas-free sampling process. It can be widely used in battery research and development, failure analysis, and safety testing. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only drawings of some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of the present invention.

[0017] Figure 1 This is a schematic diagram of the puncture sampling device of the present invention.

[0018] Figure 2 This is a schematic diagram of the method steps of the present invention.

[0019] In the picture: 1. Vacuum-sealed bag; 2. Opening; 3. Flange; 4. Sealing plug; 5. Portable vacuum sealer; 6. Sterile sampling syringe; 7. Batteries to be tested; 8. Tabs. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] like Figures 1 to 2As shown in the figure, an embodiment of the present invention provides a vacuum puncture sampling device for low-air-doped battery cell bulging gas, which includes a vacuum sealing bag 1, a flange 3, a sealing rubber stopper 4, a portable vacuum sealing machine 5, and a sterile sampling syringe 6. The entire device consists of completely lightweight, portable consumables and handheld equipment, without any large fixed equipment, complex pipelines and tooling structures, and can be carried to any location such as a laboratory, production line, or outdoor testing site for sampling operations.

[0024] The vacuum sealing bag 1 is used to wrap the bulging battery 7 to be tested. The top of the vacuum sealing bag 1 has an opening 2. The vacuum sealing bag 1 is made of any one of PE (polyethylene), PA (polyamide), PET (polyethylene terephthalate), or aluminum-plastic composite materials. All of these materials possess good airtightness, puncture resistance, and deformation resistance, effectively withstanding the pressure from irregular shapes and bulging parts of the battery casing without damage, ensuring the integrity of the seal. The vacuum sealing bag 1 has an integrated bag structure and a pre-reserved sealing edge for heat sealing by the portable vacuum sealer 5. The bag structure is simple and seamless, avoiding air leakage due to poor sealing at seams. The vacuum sealing bag 1 can be configured in various sizes (e.g., small sizes for small digital batteries, medium sizes for medium-sized energy storage batteries, and large sizes for large power batteries) to accommodate different types and volumes of bulging batteries 7, such as cylindrical, prismatic, and pouch batteries, giving the device strong versatility. After vacuuming, the vacuum-sealed bag 1 is tightly attached to the outer surface of the bulging battery 7 to be tested, and a vacuum negative pressure environment is formed inside, so that the residual air attached to the battery surface, the gap of the tab 8 and the sampling area is completely removed.

[0025] Flange 3 is located at opening 2 and is sealed and fixedly connected to vacuum-sealed bag 1. Flange 3, as the intermediate connecting component between sealing plug 4 and vacuum-sealed bag 1, is made of plastic or metal with a certain structural strength, and its lower end face is tightly fitted to the outer surface of vacuum-sealed bag 1. Flange 3 and vacuum-sealed bag 1 are seamlessly bonded through a heat-fusion sealing process, that is, the lower end face of flange 3 is fused with the bag material around opening 2 using a heat-fusion method, forming a strong connection without any air leakage gaps. The flange 3 enhances the structural strength of opening 2, preventing tearing or deformation of the bag material at opening 2 due to repeated punctures; it also provides reliable insertion space and fixed support for sealing plug 4, ensuring that sealing plug 4 remains stable and does not fall off after multiple punctures.

[0026] The sealing plug 4 is embedded and fixed inside the flange 3. The sealing plug 4 is made of elastic silicone, possessing excellent elastic deformation capacity and self-sealing performance. The thickness of the sealing plug 4 is 3mm to 8mm. This thickness range ensures moderate resistance and smooth operation during needle penetration, while also ensuring that the needle hole closes promptly and completely after puncture due to the plug's own elasticity, achieving automatic sealing. When the thickness of the sealing plug 4 is less than 3mm, the plug's rebound force is insufficient, and the needle hole cannot close completely after puncture, easily leading to gas leakage or air infiltration. When the thickness of the sealing plug 4 is greater than 8mm, the puncture resistance is too high, requiring excessive effort and easily causing the syringe needle to bend or deviate, affecting puncture accuracy. The sealing plug 4 has the ability to self-repair after multiple punctures, allowing for repeated sampling and effectively reducing sampling costs. The upper surface of the sealing plug 4 can be exposed at the upper port of the flange 3, so that the operator can insert a needle vertically from the outside; the lower surface of the sealing plug 4 is connected to the internal space of the vacuum-sealed bag 1, and the needle can directly enter the bag after penetrating the plug and further pierce the battery casing.

[0027] The portable vacuum sealer 5 is used to vacuum the vacuum-sealed bag 1 and then heat-seal the bag opening. The portable vacuum sealer 5 is a small, handheld, portable device that is lightweight, compact, and portable. It requires no fixed installation and is not limited by location or power supply conditions (it can be powered by a built-in battery). It can operate anywhere in laboratories, production lines, and outdoor testing sites. In use, the opening of the vacuum-sealed bag 1 is placed flat into the sealing slot of the portable vacuum sealer 5. The vacuuming program is started, and the portable vacuum sealer 5 automatically evacuates the air from the inside of the vacuum-sealed bag 1. Once a vacuum negative pressure environment is formed inside the bag, it automatically switches to the heat-sealing program to perform a high-temperature heat-melt seal on the bag opening, completely sealing the bulging battery 7 under test in a vacuum environment.

[0028] The sterile sampling syringe 6 is used to sequentially puncture the sealing rubber stopper 4 and the casing of the bulging battery 7 to extract gas from inside the battery. The sterile sampling syringe 6 is an airtight micro-sampling syringe with a fine-walled sterile puncture needle. It offers low puncture resistance and excellent sealing, allowing it to smoothly penetrate the sealing rubber stopper 4 and further puncture the bulging battery casing. No impurities or gas leakage occur during the entire sampling process. Before sampling, the sterile sampling syringe 6 can undergo vacuum pretreatment to remove residual air from the syringe and prevent sample contamination.

[0029] A method for vacuum puncture sampling of bulging gas in a low-air-doped battery cell, using the aforementioned apparatus, includes the following steps: S1. Pre-sampling treatment: Check the airtightness of the vacuum-sealed bag 1 and the sealing stopper 4 to ensure there is no damage or leakage. In specific operation, you can visually check whether there are holes, scratches or whether the sealing edge is intact in the bag. At the same time, you can gently squeeze the bag to observe whether there is gas leakage to ensure that the consumables are intact. Perform vacuum pre-treatment on the sterile sampling syringe 6, that is, repeatedly pump the syringe plunger 2 to 3 times to thoroughly remove the residual air inside the syringe cavity and the needle, and then let it stand for later use. This step can effectively prevent residual air inside the syringe from mixing into the gas sample to be tested, and eliminate air contamination from the sampling tool level. At the same time, according to the size and shape of the bulging battery 7 to be tested, select the corresponding specification of vacuum-sealed bag 1 to ensure that the bag can completely wrap the battery and leave an appropriate margin, which can ensure the tightness of the wrapping and avoid the bag being too large, which would reduce the vacuuming efficiency. S2. Battery Vacuum Sealing: Place the bulging battery 7, which has undergone deformation, into the vacuum sealing bag 1. When placing the battery, pay attention to adjusting its position so that the bulging area of ​​the battery is aligned with the sealing plug 4 at the top of the vacuum sealing bag 1. Ensure that the largest bulging area of ​​the battery is aligned with the central axis of the sealing plug 4. This will ensure that the syringe needle accurately pierces the gas-generating chamber of the battery along the shortest path during subsequent puncture sampling, avoiding misalignment that could cause the needle to deviate or fail to effectively enter the gas-generating area. Simultaneously, ensure that the battery tabs 8 (positive and negative leads) are completely enclosed inside the bag to prevent leaks due to dead zones at the tabs 8. Place the opening of the vacuum sealing bag 1 flat into the sealing groove of the portable vacuum sealing machine 5, aligning the bag opening with the heating strip of the sealing groove. Avoid folding or tilting the bag opening to ensure the sealing quality of the subsequent heat sealing. S3. Vacuum Sealing and Forming: The portable vacuum sealer 5 is started, and it begins to evacuate the air from inside the vacuum-sealed bag 1, removing all the air. As the evacuation process continues, the bag gradually shrinks and adheres to the outer surface of the battery until it completely adheres to the battery surface, creating a vacuum environment inside. At this point, the air adhering to the battery surface, the air remaining in the gaps of the battery tabs 8, and the air inside the bag are all completely removed. Subsequently, the portable vacuum sealer 5 automatically starts the heat-sealing process to seal the vacuum. The opening of bag 1 is sealed by high-temperature heat fusion to completely seal the bag, so that the bulging battery 7 to be tested is completely in a vacuum-sealed, airless environment. After sealing, it is left to stand for 1 to 3 minutes. This standing process is used to allow the negative pressure inside the bag to stabilize, and at the same time, observe whether the bag slowly rebounds (rebound indicates air leakage). This ensures that the seal is reliable and the bag is leak-free, providing a stable and pure vacuum environment for subsequent puncture sampling. If the bag rebounds significantly or cannot maintain a tight seal during the standing period, it indicates that the seal has failed and a new vacuum-sealed bag 1 needs to be replaced and resealed. S4. Closed-loop puncture sampling: Holding the sterile sampling syringe 6 pretreated in step S1, vertically pierce the sealing plug 4 at the top of the vacuum-sealed bag 1. During puncture, the needle should be advanced at a uniform speed perpendicular to the upper surface of the sealing plug 4 to reduce puncture resistance and plug deformation. After penetrating the sealing plug 4, the needle enters the vacuum-sealed bag 1. At this point, it is necessary to accurately aim at the bulging area of ​​the battery and continue to slowly advance the needle to pierce the battery casing, so that the inner cavity of the syringe is connected to the gas-generating chamber inside the battery. Since the entire puncture process is completed inside the vacuum-sealed bag 1... Furthermore, the sealing plug 4 tightly wraps around the needle shaft when the needle passes through, preventing outside air from entering the bag through the puncture gap; after the needle pierces the battery casing, it is left to stand for 1 to 2 minutes. This standing process is used to allow the unstable pressure inside the battery caused by the puncture disturbance to return to equilibrium, ensuring the representativeness of gas composition and pressure during subsequent sampling; after the gas pressure inside the battery stabilizes, the syringe plunger is pulled at a uniform speed to quantitatively extract the original bulging gas inside the battery. During the extraction process, the plunger should be pulled at a uniform speed to avoid airflow disturbance or gas component separation due to excessive speed; S5. Sampling Completion and Sample Sealing: After gas extraction is completed, the syringe needle is pulled out at a uniform speed to avoid severe deformation or local damage to the rubber stopper caused by rapid needle withdrawal. After the needle is completely pulled out, the sealing rubber stopper 4 automatically rebounds and closes due to its own elasticity. The needle hole quickly contracts and closes under the elastic action of the rubber stopper, restoring the vacuum sealing bag 1 to a sealed state, with no gas leakage and no infiltration of outside air. Subsequently, the syringe needle containing the gas to be tested is sealed (e.g., by attaching a sealing cap), and the sample number, test conditions, and other information are marked to complete a single sampling operation. The collected sample can be directly sent to gas chromatographs, mass spectrometers, and other detection equipment for gas composition analysis without additional transfer operations, avoiding air contamination of the sample during transfer.

[0030] In the above sampling method, the vacuum-sealed bag 1 is completely attached to the battery surface after vacuuming, with no residual air inside. The puncture and sampling process is completed in the vacuum-sealed bag environment without the intervention of external air, thus eliminating the interference of air impurities on the gas to be tested from the source. Example

[0031] This embodiment provides a method for sampling low-doped gas from the swelling gas of a soft-pack battery. The sampling is performed using an aluminum-plastic composite vacuum sealing bag, a handheld portable vacuum sealer, a silicone self-sealing stopper, and a sterile airtight syringe. The specific steps are as follows: 1. Equipment and consumables pretreatment: Select aluminum-plastic vacuum sealing bags with a thickness of 0.12mm, and check that the bags are undamaged and leak-free; heat-seal and fix the 5mm thick elastic silicone rubber stopper to the center of the top of the vacuum bag to ensure a complete seal at the connection; repeatedly draw and expel 10mL sterile sampling syringes 3 times to thoroughly remove any residual air inside, and set aside for later use. 2. Battery bagging and positioning: Place the batteries that have bulged after the high-temperature cycling test into an aluminum-plastic vacuum-sealed bag, and adjust the battery angle so that the largest bulging area of ​​the battery is aligned with the center of the top sealing plug to ensure accurate puncture point. 3. Vacuum sealing: Place the vacuum bag opening flat into the portable vacuum sealing machine, start the vacuuming program, extract the air from the bag until the bag body is tightly attached to the battery surface, and a vacuum environment is formed inside. Then start the heat sealing program to heat melt and seal the bag opening. Let it stand for 2 minutes to confirm that the bag body has no rebound and no air leakage. 4. Vacuum environment puncture sampling: The sterile syringe needle is vertically punctured through the silicone stopper, and the needle is continued to puncture the battery bulge shell. After the needle is completely inserted into the battery gas generation chamber, it is left to stand for 1.5 minutes to balance the pressure, and the push rod is pulled at a uniform speed to extract 5mL of gas generated inside the battery. 5. Sample sealing and testing: After sampling, slowly pull out the needle. The rubber stopper will automatically spring back and seal, isolating the inside and outside air. Seal the syringe needle with a sealing cap, mark the sample number and test conditions, and send it into the gas chromatograph for gas composition detection. High-precision gas chromatography quantitative detection was performed, using the absence of endogenously generated nitrogen from the battery as the criterion for quantitative determination of air doping. In this embodiment, the residual nitrogen content in the gas sample was only 0.18%, meaning the overall air doping rate was only 0.18%, indicating extremely low air impurity content. Characteristic components in the original battery production gas, such as hydrogen, carbon dioxide, methane, and trace amounts of fluorinated organic compounds, were detected completely and without distortion, without dilution interference from air components. This allows for accurate qualitative and quantitative analysis with extremely high sampling purity and detection accuracy.

[0032] This comparative example strictly follows the principle of single-variable testing. Except for not using the vacuum bag integral vacuum sealing structure of this invention, all other test conditions are completely consistent with the embodiments of this invention. The specific limiting conditions are as follows: the batteries under test are soft-pack batteries of the same batch, specifications, and production process, and have undergone the same high-temperature cycle test conditions, with consistent swelling degree and internal gas production state; the ambient temperature, ambient pressure, sampling settling time, gas extraction volume, sampling syringe specifications, testing instruments, testing parameters, and analysis methods are all kept consistent with the embodiments, only changing the sampling environment and sampling sealing method, to objectively compare the technical superiority of this invention.

[0033] Specific operating steps: Under standard atmospheric pressure, use a 10mL sterile airtight syringe identical to the one used in the example, and pre-pump and purge the syringe to remove residual air; directly puncture the battery's largest bulge shell with the syringe needle vertically, let it stand for 1.5 minutes until the internal air pressure of the battery and the tubing pressure are balanced, then uniformly extract 5mL of the bulging gas inside the battery. After sampling, immediately seal the syringe needle port to complete the preparation of the comparative sample.

[0034] The comparative sample and the sample from the embodiment of the present invention were tested simultaneously. The nitrogen content was used to characterize the air doping rate. The quantitative test results showed that the nitrogen doping rate of the sample obtained by the traditional bare direct sampling method was as high as 12.3%. A large amount of outside air mixed into the sample through the puncture gap and the open environment. Due to the dilution interference of a large amount of air impurities, the signal-to-noise ratio of the battery's original trace characteristic gas-producing components was significantly reduced. The peak intensity of methane and trace carbon and fluorine failure characteristic components was severely attenuated. The relative detection error was greater than 15%, making it impossible to accurately determine the gas production law and failure mechanism of the battery side reaction. The data was severely distorted and the detection reliability was extremely poor.

[0035] Rigorous single-variable controlled experiments clearly demonstrate that existing traditional direct syringe sampling methods cannot avoid problems such as air ingress through puncture gaps, residual gas on the battery surface, and air backflow, resulting in extremely high nitrogen contamination, severe pollution, and poor detection accuracy. In contrast, this invention employs a lightweight and portable solution through overall battery vacuum encapsulation, full-area pre-degassing, and self-sealing with a rubber stopper to prevent air impurities from entering at the source, stably controlling the air contamination rate (measured in nitrogen) to within 0.2%, achieving an order-of-magnitude improvement in sampling purity. Furthermore, this invention relies on a purely lightweight handheld consumable device, eliminating the need for fixed workstations and large vacuum equipment, combining high precision, low cost, and portability across all scenarios. It effectively resolves the industry technical contradiction of existing technologies where "high-precision sampling relies on heavy equipment, and portable sampling has poor accuracy," demonstrating significant technological advancement and high engineering application value.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A vacuum puncture sampling device for bulging gas in a low-air-doped battery cell, characterized in that, include: A vacuum-sealed bag (1) is used to wrap the bulging battery (7) to be tested. The top of the vacuum-sealed bag (1) has an opening (2). Flange (3) is provided at the opening (2) and is sealed and fixedly connected to the vacuum sealing bag (1); A sealing plug (4) is embedded and fixed inside the flange (3); A portable vacuum sealer (5) is used to vacuum the vacuum-sealed bag (1) and heat-seal the bag opening; A sterile sampling syringe (6) is used to sequentially puncture the sealing rubber plug (4) and the casing of the bulging battery (7) to extract the gas inside the battery.

2. The vacuum puncture sampling device for low-air-doped battery cell bulging gas according to claim 1, characterized in that: The vacuum-sealed bag (1) is made of any one of PE, PA, PET or aluminum-plastic composite materials.

3. The vacuum puncture sampling device for low-air-doped battery cell expansion gas according to claim 1, characterized in that: The sealing plug (4) is made of elastic silicone.

4. The vacuum puncture sampling device for low-air-doped battery cell bulging gas according to claim 1, characterized in that: The flange (3) and the vacuum sealing bag (1) are seamlessly bonded together by a hot melt sealing process.

5. The vacuum puncture sampling device for low-air-doped battery cell expansion gas according to claim 1, characterized in that: The vacuum sealing bag (1) is an integrated bag structure, and has a reserved sealing edge for the portable vacuum sealing machine (5) to heat-seal.

6. The vacuum puncture sampling device for low-air-doped battery cell bulging gas according to claim 1, characterized in that: The thickness of the sealing plug (4) is 3mm to 8mm.

7. The vacuum puncture sampling device for low-air-doped battery cell expansion gas according to claim 1, characterized in that: The sterile sampling syringe (6) is an airtight micro-sampling syringe with a fine-walled sterile puncture needle.

8. A method for vacuum puncture sampling of bulging gas in a low-air-doped battery cell, using the apparatus described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Pre-sampling treatment: Check the airtightness of the vacuum sealing bag (1) and sealing plug (4) to confirm that there is no damage or leakage; perform vacuum pre-treatment on the sterile sampling syringe (6) to remove the residual air inside and set it aside for later use; select a vacuum sealing bag (1) of the corresponding specification to fit the size of the bulging battery (7) to be tested. S2, Battery vacuum sealing: Place the bulging battery (7) to be tested into the vacuum sealing bag (1) smoothly, adjust the battery position so that the bulging area of ​​the battery is aligned with the sealing plug (4) at the top of the vacuum sealing bag (1) to ensure accurate alignment for subsequent puncture sampling; place the opening of the vacuum sealing bag (1) flat into the sealing groove of the portable vacuum sealing machine (5); S3. Vacuum sealing and molding: Start the portable vacuum sealer (5) to extract all the air inside the vacuum sealing bag (1). After the bag body is completely attached to the outer surface of the battery and a vacuum negative pressure environment is formed inside, start the hot-press sealing program to perform high-temperature hot-melt sealing on the bag mouth of the vacuum sealing bag (1) so that the bulging battery (7) to be tested is completely in a vacuum-sealed airless environment. Let it stand for 1-3 minutes to ensure that the negative pressure of the bag body is stable and the sealing is reliable. S4. Closed puncture sampling: Hold the pre-treated sterile sampling syringe (6) and vertically pierce the sealing plug (4) at the top of the vacuum-sealed bag (1). After piercing the sealing plug (4), accurately aim at the bulging area of ​​the battery and slowly pierce the battery shell to make the inner cavity of the syringe connected with the gas-generating chamber inside the battery. Let it stand for 1-2 minutes until the gas pressure inside the battery stabilizes. Then, pull the syringe plunger at a uniform speed to quantitatively extract the original bulging gas inside the battery. S5. Sampling and sealing: After the gas extraction is completed, quickly pull out the syringe needle. The sealing rubber stopper (4) automatically rebounds and closes due to its own elasticity, restoring the vacuum sealing bag (1) to a closed state with no gas leakage and no air infiltration. Seal the syringe needle that has extracted the gas to be tested, mark the sample information, complete the single sampling operation, and send it directly to the gas chromatography and mass spectrometry detection equipment for component analysis.

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