Gas sampling device and gas production detection device for soft package battery

Abstract

The utility model relates to battery technical field discloses the gas sampling device and gas production detection device of soft package battery, the gas sampling device of soft package battery, soft package battery includes composite film shell, is provided with the round notch on the aluminum shell, is fixedly connected with the external thread screw joint in the round notch, the gas sampling assembly includes soft package battery and gas sampling assembly, the gas sampling assembly includes the connecting air pipe, puncture needle, connecting sleeve, first screw cap. The gas sampling device of soft package battery provided by the utility model is easy to process, and the test method is simple, convenient operation has universality, and can be applicable to all sizes of soft package battery, especially suitable for lithium ion or sodium ion battery gas production test, can collect or analyze the gas sample according to the need at any time.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, and in particular relates to a gas sampling device and a gas production detection device for soft-pack batteries. Background Technology

[0002] Sodium-ion or lithium-ion batteries generate gas during the formation of the SEI film during the first charge and discharge process. The gas components are mostly alkanes, alkenes, hydrogen and carbon monoxide. Lithium-ion batteries also generate gas during various tests, such as overcharging, over-discharging, high-temperature storage and cycle testing. This leads to increased internal pressure in the battery, deterioration of battery performance, and even damage to the casing, resulting in safety accidents.

[0003] In battery failure analysis, the failure reaction mechanism is usually analyzed by combining the gas composition and gas production of the battery. Gas production testing of pouch batteries is generally done by measuring changes in their volume; however, testing the composition and content of the produced gas is relatively difficult. CN206095503U describes an online monitoring device for the internal gas pressure of a cylindrical lithium-ion battery. This patent can only monitor the internal pressure of the battery and cannot monitor the composition of the produced gas in real time. CN201620946362 proposes an online gas composition analysis device for a square aluminum-cased lithium battery, which extracts the generated gas from the battery's filling port for testing, but this patent does not cover the details of the gas extraction process. CN110376531A provides a method for gas extraction using a fixed rivet design; however, this process is entirely made of stainless steel, which poses a possibility of cation contamination, and the material cannot be completely sealed with plastic, posing a possibility of gas leakage and the introduction of external contamination. CN219714911U and N108548874A disclose a device for gas extraction from a battery via puncture. However, this device still belongs to the design of separating the needle from the battery pack. The simple puncture design cannot eliminate external contamination and leakage.

[0004] Therefore, there is an urgent need for gas sampling devices and gas production detection devices for pouch batteries to solve the above-mentioned technical problems. Utility Model Content

[0005] The purpose of this invention is to overcome the existing technical problems and provide a gas sampling device and a gas production detection device for soft-pack batteries.

[0006] To achieve the above objectives, this utility model is implemented according to the following technical solution:

[0007] A gas sampling device for a pouch battery includes a pouch battery and a gas sampling assembly. The pouch battery includes a composite membrane shell, and a positive electrode, a negative electrode, a separator placed between the positive and negative electrodes, and an electrolyte encapsulated within the composite membrane shell. The composite membrane shell includes an outer aluminum shell and a polypropylene (PP) liner disposed on the inner side of the aluminum shell. A circular notch is provided on the aluminum shell. An external threaded interface is fixedly connected within the circular notch. The external threaded interface is an integral structure, including an upper external threaded connecting pipe and a bottom connecting seat.

[0008] The center of the external thread interface is provided with a first through hole;

[0009] The gas sampling assembly includes a connecting tube, a puncture needle, a connecting sleeve, and a first threaded cap;

[0010] The connecting sleeve is an integral structure, including an upper external threaded sleeve and a lower internal threaded sleeve; the center of the external threaded sleeve has a second through hole;

[0011] The first threaded cap has a third through hole in its center; the first threaded cap is threadedly connected to the external threaded sleeve.

[0012] The puncture needle is a hollow tube. The head of the puncture needle extends into the second through hole and is fixedly connected to the second through hole; the tail of the puncture needle has a beveled surface.

[0013] The connecting tube passes through the third through hole and is fixedly connected to the third through hole; the connecting tube is coaxial with the puncture needle.

[0014] The external threaded connecting pipe is matched with the internal threaded sleeve; the inner diameter of the first through hole is larger than the outer diameter of the puncture needle; when the lower end face of the internal threaded sleeve contacts the upper end face of the connecting seat, the puncture needle pierces the polypropylene liner below the circular notch.

[0015] In a further preferred embodiment, when the lower end face of the internal threaded sleeve contacts the upper end face of the connecting seat, the oblique cut surface of the puncture needle tail penetrates the polypropylene liner below the circular notch and extends into the soft-pack battery.

[0016] Preferably, the pouch battery also includes a second threaded cap; the second threaded cap matches the outer threaded sleeve.

[0017] Specifically, the second threaded cap is made of polypropylene.

[0018] Preferably, the soft-pack battery also includes a U-shaped positioning pin; the positioning pin is disposed between the lower end face of the internal threaded sleeve and the upper end face of the connecting seat; when the lower end face of the internal threaded sleeve contacts the upper end face of the positioning pin, and the lower end face of the positioning pin contacts the upper end face of the connecting seat, the tail of the puncture needle is located above the polypropylene liner at the circular notch.

[0019] Preferably, the height of the locating pin is 1.05 to 1.15 times the axial height corresponding to the beveled surface of the puncture needle tail. This axial height setting ensures that when the lower end face of the internal threaded sleeve contacts the upper end face of the connecting seat after the locating pin is removed, the beveled surface of the puncture needle tail can extend into the pouch battery.

[0020] The axial height mentioned above refers to the height of the cylinder corresponding to the oblique section in the vertical direction.

[0021] Specifically, the locating pin is made of polypropylene.

[0022] Preferably, the external threaded interface is made of polypropylene; the puncture needle, connecting sleeve, and first threaded cap are all made of polyetheretherketone (PEEK); and the connecting tube is made of polypropylene or stainless steel.

[0023] Preferably, the angle between the oblique surface of the puncture needle and the horizontal plane is 45° to 60°.

[0024] Preferably, the ratio of the inner diameter of the puncture needle to the outer diameter of the puncture needle is 1:3.

[0025] Specifically, the upper end of the puncture needle is positioned lower than the upper end of the external threaded sleeve, and the upper end of the puncture needle is sealed to the second through hole via fluororubber.

[0026] Furthermore, the connecting tube is fixedly connected to the first threaded cap, and the gap between the connecting tube and the first threaded cap is sealed with fluororubber, so that the connecting tube and the first threaded cap are fixed and sealed.

[0027] Preferably, a washer is fitted on the puncture needle at the upper part of the external thread interface; a second washer is fitted on the connecting air tube at the lower part of the third through hole.

[0028] The gas production detection device includes the aforementioned gas sampling device and a detection device connected to the gas sampling device; the detection device includes at least one of an infrared spectrometer, a gas chromatograph, a mass spectrometer, and a gas chromatography-mass spectrometry system.

[0029] The testing equipment is connected to the gas sampling device via a pipeline.

[0030] Preferably, the external spectrometer is a Fourier transform infrared spectrometer.

[0031] Preferably, the infrared spectrometer uses a 10cm gas flow cell made of stainless steel.

[0032] Preferably, the infrared spectrometer uses a calcium fluoride window.

[0033] Preferably, the gas chromatography-mass spectrometry system uses a 5A column, a Q column, or a DB-200 column for separation.

[0034] Preferably, the gas chromatography-mass spectrometry system employs a valve switching method and uses a thermal conductivity detector (TCD) in parallel with a mass spectrometer (MS) for detection.

[0035] Preferably, the infrared spectrometer uses the standard curve method for quantitative analysis.

[0036] Preferably, the gas chromatography-mass spectrometry system uses the internal standard method for quantitative analysis.

[0037] Specifically, the gas production detection device includes the aforementioned gas sampling device, a polypropylene pipeline, and an infrared spectrometer and a gas chromatography-mass spectrometry system connected sequentially to the polypropylene pipeline; a helium source, a metering loop, and a vacuum device are also connected sequentially to the pipeline before the infrared spectrometer; the metering loop is directly connected to the polypropylene pipeline; the helium source and the vacuum device are both connected to the polypropylene pipeline through three-way valves.

[0038] More specifically, the metering ring is a 1 mL stainless steel metering ring.

[0039] More specifically, vacuum devices are vacuum systems that do not require a medium, such as diaphragm pumps and vacuum pumps, to complete the evacuation process.

[0040] Mechanism of action:

[0041] Because the gas sampling device requires destructive penetration into the pouch battery, the material must possess sufficient puncture force against the battery's polypropylene casing while avoiding contamination by metal ions (to ensure the stability of the battery's charging and discharging system). The material should also be resistant to a certain level of acidity and organic solvent corrosion. When the puncture needle enters the pouch battery, its seal should be completely free of dead volume, and there should be no gaps between the puncture edge and the pouch battery to prevent leakage, internal gas loss, and environmental contamination. Therefore, the puncture needle used in the test should be able to share the same system as the pouch battery. Considering these factors, the puncture needle and pouch battery in this novel design can be integrated as a single unit during testing, preventing leakage and contamination.

[0042] In use, the pouch cells to be tested are first assembled and sealed. Then, the positive and negative terminals of the pouch cells are connected to a battery charging / discharging device for testing. After sufficient cycling and testing, the pouch cells will produce a certain amount of bulging gas. The gas produced inside the pouch cells can then be measured.

[0043] During testing, remove the second threaded cap from the pouch battery. Connect the pouch battery and the gas sampling assembly via the external thread interface and the internal thread sleeve. Connect the gas tube to the gas generation detection device. Degas the gas sampling assembly and the metering loop using the vacuum device of the gas generation detection device. Then disconnect the vacuum device, remove the locating pin from the pouch battery, and tighten the internal thread sleeve to the bottom. At this point, the polyetheretherketone (PEEK) puncture needle will pierce the polypropylene liner and enter the pouch battery. Connect the gas tube to the gas generation detection device. Then switch the three-way valve to a helium source (such as a helium cylinder). Use helium as the carrier gas to send the gas to be tested in the metering loop into the infrared spectrometer and gas chromatography-mass spectrometry (GC-MS) instrument. Using infrared spectroscopy and GC-MS, battery gas generation can be tested without the introduction of external contamination.

[0044] In the gas generation detection device, the infrared spectrometer is first connected through a polypropylene pipeline to quantitatively detect the polar molecules; then it enters a gas chromatography-mass spectrometry system to separate non-polar molecules using a 5A column and a Q column; then it switches to a DB-200 column for MS testing; after the detection is completed, it switches back to a TCD for non-polar molecule detection.

[0045] In this novel structure, the interface module (gas sampling component) required for testing is introduced during the manufacturing process of the soft-pack battery. However, before testing, since the polypropylene liner does not deform, there are no changes in the battery pack caused by the sampling module or other factors that are detrimental to battery manufacturing.

[0046] When the test begins, a puncture needle made of polyetheretherketone (PEEK) is inserted into the battery, but not deep enough to puncture the battery separator. At the same time, the material can resist possible corrosion from the internal electrolyte and does not release interfering substances.

[0047] When the test begins, the system contains only the gas generated by the pouch cell itself, with almost no dead volume and no external polluting gases or impurities introduced.

[0048] When testing is performed, the gas is controlled by a quantitative loop, which eliminates the deviation caused by fluctuations in the sampling volume.

[0049] When performing detection, infrared spectroscopy can accurately distinguish and quantitatively detect samples, and the quantitative results can be used as internal standards. This improves the accuracy of gas chromatography-mass spectrometry (GC-MS) detection.

[0050] When the sampled gas changes, the composition of the gas entering the mass spectrometer can be adjusted by changing the valve switching time, thereby enabling qualitative analysis and detection of gases without infrared absorption.

[0051] This device allows for the collection and analysis of gas samples as needed.

[0052] The description of the soft-pack battery not specified in this utility model adopts the prior art; for example, the composite film shell actually refers to the composite film of aluminum film and polypropylene, which are named aluminum shell and polypropylene (PP) liner respectively.

[0053] Components not specified in this invention are all made using conventional methods in the field. Those skilled in the art can select their models and installation methods according to actual usage needs, and clearly understand how to install and control them. They will not be described in detail here.

[0054] This utility model achieves the following beneficial effects:

[0055] The gas sampling device for pouch batteries provided by this invention is easy to manufacture, has a simple testing method, is convenient to operate, and is universally applicable. It is suitable for pouch batteries of various sizes, and is especially suitable for testing gas generation from lithium-ion or sodium-ion batteries. Gas samples can be collected or analyzed as needed at any time. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present utility model;

[0057] Figure 2 for Figure 1 A schematic diagram of the structure after removing the first threaded cap and connecting air tube and connecting the second threaded cap;

[0058] Figure 3 for Figure 1 Top view of the center locating pin;

[0059] Figure 4 for Figure 1 Schematic diagram of the structure of the gas recovery unit;

[0060] Figure 5 This is a schematic diagram of the gas collection state of the gas collection component in Embodiment 1 of this utility model;

[0061] Figure 6 This is a schematic diagram of the test connection of the gas generation detection device in Embodiment 1 of this utility model.

[0062] In the diagram: 1. Aluminum outer shell; 2. Polypropylene inner liner; 3. External threaded connecting pipe; 4. Connecting seat; 5. First through hole; 6. Second threaded cap; 7. Connecting air tube; 8. Puncture needle; 9. First threaded cap; 10. External threaded sleeve; 11. Internal threaded sleeve; 12. Second through hole; 13. Third through hole; 14. Positioning pin; 15. First washer; 16. Second washer; 17. Fluororubber. Detailed Implementation

[0063] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0064] Example 1

[0065] like Figures 1 to 5 As shown, the gas sampling device for the pouch battery includes the pouch battery and the gas sampling assembly.

[0066] The soft-pack battery includes a composite film shell, and a positive electrode, a negative electrode, a separator placed between the positive and negative electrodes, and an electrolyte encapsulated within the composite film shell. The composite film shell includes an outer aluminum shell 1 and a polypropylene inner liner 2 disposed on the inner side of the aluminum shell. A circular notch is provided on the aluminum shell. An external threaded interface is fixedly connected within the circular notch. The external threaded interface is an integral structure, including an upper external threaded connecting pipe 3 and a bottom connecting seat 4. A first through hole 5 is provided at the center of the external threaded interface.

[0067] The pouch battery also includes a second threaded cap 6; the second threaded cap matches the outer threaded sleeve. The gas sampling assembly includes a connecting gas tube 7, a puncture needle 8, a connecting sleeve, and a first threaded cap 9;

[0068] The connecting sleeve is an integral structure, including an upper external threaded sleeve 10 and a lower internal threaded sleeve 11; the center of the external threaded sleeve has a second through hole 12.

[0069] The first threaded cap has a third through hole 13 at its center; the first threaded cap is threadedly connected to the external threaded sleeve.

[0070] The puncture needle is a hollow tube. The head of the puncture needle extends into the second through hole and is fixedly connected to the second through hole; the tail of the puncture needle has a beveled surface.

[0071] The connecting tube passes through the third through hole and is fixedly connected to the third through hole; the connecting tube is coaxial with the puncture needle.

[0072] The external threaded connecting pipe is matched with the internal threaded sleeve; the inner diameter of the first through hole is larger than the outer diameter of the puncture needle; when the lower end face of the internal threaded sleeve contacts the upper end face of the connecting seat, the puncture needle pierces the polypropylene liner below the circular notch.

[0073] The pouch battery also includes a U-shaped locating pin 14; the locating pin is positioned between the lower end face of the internal threaded sleeve and the upper end face of the connecting seat; when the lower end face of the internal threaded sleeve contacts the upper end face of the locating pin, and the lower end face of the locating pin contacts the upper end face of the connecting seat, the tail of the puncture needle is located above the polypropylene liner at the circular notch. The height of the locating pin is 1.1 times the axial height corresponding to the beveled surface of the tail of the puncture needle.

[0074] The external threaded interface, positioning pin, and second threaded cap are all made of polypropylene; the puncture needle, connecting sleeve, and first threaded cap are all made of polyetheretherketone; and the connecting tube is made of polypropylene.

[0075] The angle between the beveled surface of the puncture needle and the horizontal plane is 48.1°. The ratio of the inner diameter of the puncture needle to its outer diameter is 1:3.

[0076] A first washer 15 is fitted on the puncture needle at the upper part of the external thread interface, and a second washer 16 is fitted on the connecting air tube at the lower part of the third through hole.

[0077] The upper end of the puncture needle is positioned lower than the upper end of the external threaded sleeve, and the upper end of the puncture needle is sealed to the second through hole via fluororubber 17.

[0078] Example 2

[0079] like Figure 6 As shown, the gas production detection device includes the gas sampling device of Example 1, a polypropylene pipeline, and an infrared spectrometer and a gas chromatography-mass spectrometry system connected in sequence to the polypropylene pipeline; a helium source, a metering loop, and a vacuum device are also connected in sequence to the pipeline before the infrared spectrometer; the metering loop is directly connected to the polypropylene pipeline; the helium source and the vacuum device are both connected to the polypropylene pipeline through a three-way valve; the polypropylene pipeline is connected to the gas sampling device via a connecting pipe.

[0080] The infrared spectrometer uses a 10cm gas flow cell made of stainless steel and a calcium fluoride window.

[0081] The gas chromatography-mass spectrometry system uses 5A columns, Q columns, and DB-200 columns for separation.

[0082] The gas chromatography-mass spectrometry system uses a valve switching method and employs a thermal conductivity detector (TCD) in parallel with a mass spectrometer (MS) for detection.

[0083] Infrared spectroscopy uses the standard curve method for quantitative analysis. Gas chromatography-mass spectrometry uses the internal standard method for quantitative analysis.

[0084] The metering ring is a 1mL stainless steel metering ring; the vacuum device is a diaphragm pump.

[0085] In this embodiment, the pouch cell battery to be tested is first assembled and sealed. Then, the positive and negative terminals of the pouch cell battery are connected to a battery charging and discharging device to perform the corresponding tests. After sufficient cycling and experimental testing, the pouch cell battery will produce a certain amount of bulging gas. At this time, the gas generated inside the pouch cell battery can be measured.

[0086] During testing, remove the second threaded cap from the pouch battery. Connect the pouch battery and the gas sampling assembly via the external thread interface and the internal thread sleeve. Connect the gas tube to the gas generation detection device. Degas the gas sampling assembly and the metering ring using the vacuum device of the gas generation detection device. Then disconnect the vacuum device, remove the locating pin from the pouch battery, and tighten the internal thread sleeve to the bottom. At this point, the polyetheretherketone (PEEK) puncture needle will pierce the polypropylene liner and enter the pouch battery. Connect the gas tube to the gas generation detection device. Then switch the three-way valve to a helium source (such as a helium cylinder). Use helium as the carrier gas to send the gas to be tested in the metering ring into the infrared spectrometer and gas chromatography-mass spectrometry (GC-MS) instrument. Using infrared spectroscopy and GC-MS, battery gas generation can be tested without the introduction of external contamination.

[0087] In the gas generation detection device, the infrared spectrometer is first connected through a polypropylene pipeline to quantitatively detect the polar molecules; then it enters a gas chromatography-mass spectrometry system to separate non-polar molecules using a 5A column and a Q column; then it switches to a DB-200 column for MS testing; after the detection is completed, it switches back to a TCD for non-polar molecule detection.

[0088] The technical solution of this utility model is not limited to the specific embodiments described above. All technical modifications made based on the technical solution of this utility model shall fall within the protection scope of this utility model.

Claims

1. A gas sampling device for a pouch cell battery, comprising a pouch cell battery and a gas sampling assembly; the pouch cell battery includes a composite membrane casing, and a positive electrode, a negative electrode, a separator placed between the positive and negative electrodes, and an electrolyte encapsulated within the composite membrane casing; characterized in that: The composite membrane shell includes an outer aluminum shell and a polypropylene liner disposed on the inner side of the aluminum shell; the aluminum shell has a circular notch; an external threaded interface is fixedly connected in the circular notch; the external threaded interface is an integral structure, including an upper external threaded connecting pipe and a bottom connecting seat. The center of the external thread interface is provided with a first through hole; The gas sampling assembly includes a connecting tube, a puncture needle, a connecting sleeve, and a first threaded cap; The connecting sleeve is an integral structure, including an upper external threaded sleeve and a lower internal threaded sleeve; the center of the external threaded sleeve has a second through hole; The first threaded cap has a third through hole in its center; the first threaded cap is threadedly connected to the external threaded sleeve. The puncture needle is a hollow tube. The head of the puncture needle extends into the second through hole and is fixedly connected to the second through hole; the tail of the puncture needle has a beveled surface. The connecting tube passes through the third through hole and is fixedly connected to the third through hole; the connecting tube is coaxial with the puncture needle. The external threaded connecting pipe is matched with the internal threaded sleeve; the inner diameter of the first through hole is larger than the outer diameter of the puncture needle; when the lower end face of the internal threaded sleeve contacts the upper end face of the connecting seat, the puncture needle pierces the polypropylene liner below the circular notch.

2. The gas sampling device for a pouch battery according to claim 1, characterized in that: The pouch battery also includes a second threaded cap; the second threaded cap matches the outer threaded sleeve.

3. The gas sampling device for a soft-pack battery according to claim 1, characterized in that: The soft-pack battery also includes a U-shaped locating pin; the locating pin is located between the lower end face of the internal threaded sleeve and the upper end face of the connecting seat; when the lower end face of the internal threaded sleeve contacts the upper end face of the locating pin, and the lower end face of the locating pin contacts the upper end face of the connecting seat, the tail of the puncture needle is located above the polypropylene liner at the circular notch.

4. The gas sampling device for a pouch battery according to claim 1, characterized in that: The external threaded interface is made of polypropylene; the puncture needle, connecting sleeve, and first threaded cap are all made of polyetheretherketone; the connecting tube is made of polypropylene or stainless steel.

5. The gas sampling device for a pouch battery according to claim 1, characterized in that: The angle between the oblique cut of the puncture needle and the horizontal plane is 45° to 60°.

6. The gas sampling device for a pouch battery according to claim 1, characterized in that: The ratio of the inner diameter of the puncture needle to its outer diameter is 1:

3.

7. The gas sampling device for a pouch battery according to claim 1, characterized in that: A first washer is fitted on the puncture needle at the upper part of the external threaded interface; a second washer is fitted on the connecting air tube at the lower part of the third through hole.

8. A gas production detection device, characterized in that; The invention includes the gas sampling device as described in any one of claims 1-7, and a detection device connected to the gas sampling device; the detection device includes at least one of an infrared spectrometer, a gas chromatograph, a mass spectrometer, and a gas chromatography-mass spectrometry system. The testing equipment is connected to the gas sampling device via a pipeline.

Images