Method for measuring gas production of cylindrical batteries

Abstract

The application provides a method for measuring the gas production of a cylindrical battery, comprising the following steps: providing a cylindrical battery cell to be sealed and a positive electrode cover, punching the positive electrode cover; sealing the positive electrode of the cylindrical battery to be sealed by using the positive electrode cover which has been punched; respectively welding the positive and negative electrode black glue nickel tabs on the positive and negative electrodes; respectively wrapping the positive and negative electrode black glue nickel tabs by using high-temperature-resistant adhesive tape, wrapping the cylindrical battery cell by using an aluminum plastic film, and making two black glue nickel tabs exposed from one end of the positive electrode of the battery, so as to obtain a cylindrical battery cell to be measured; providing a container containing liquid, placing the container on a loading platform of a weighing instrument, immersing the cylindrical battery cell to be measured in the liquid, and making the cylindrical battery cell to be measured not touch the wall, and measuring the gas production of the cylindrical battery cell to be measured.

Description

Technical Field

[0001] This invention belongs to the research field of lithium-ion battery gas production testing technology, and particularly relates to a method for measuring the gas production of cylindrical batteries. Background Technology

[0002] In recent years, the demand for increased capacity and cycle life of lithium-ion batteries has been growing. Consequently, high-capacity high-nickel materials and silicon-based materials have attracted increasing attention from companies and researchers, with particular focus on the cycle failure of high-nickel and silicon-based anodes. For long-cycle-life cylindrical batteries, although the structural characteristics of the materials themselves play a dominant role, the amount of gas produced inside the battery gradually increases with continuous cycling. When the gas production reaches a certain level, the internal pressure of the cylindrical battery increases, altering the interaction between the electrolyte and the positive and negative electrode materials, thus affecting battery performance. Therefore, the amount of gas produced inside a cylindrical battery is a crucial parameter affecting battery performance. Effective monitoring of the gas production inside a cylindrical battery can improve the yield of cylindrical battery products. Typically, to collect the gas produced by a cylindrical battery, a collection device is needed to collect the gas inside the battery, and the gas must be kept leak-proof during the collection process. This method is cumbersome. Therefore, finding a simple and accurate method to measure the amount of gas produced inside a cylindrical battery is particularly important. Summary of the Invention

[0003] The purpose of this invention is to provide a method for measuring the gas production of cylindrical batteries, aiming to solve the problem of cumbersome operation in existing methods for testing the gas production of cylindrical batteries.

[0004] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0005] This invention provides a method for measuring the gas production of a cylindrical battery, comprising the following steps:

[0006] Provide a cylindrical battery cell to be sealed and a positive electrode cap, and punch a hole in the positive electrode cap;

[0007] The positive electrode cap, after being perforated, is used to seal the positive electrode of the cylindrical battery to be sealed, and the battery is assembled into a rough cylindrical battery cell product. Positive black glue nickel tabs and negative black glue nickel tabs are welded to the positive and negative electrodes of the rough cylindrical battery cell product, respectively, wherein the negative black glue nickel tabs extend to one end of the positive electrode.

[0008] High-temperature resistant tape was used to wrap the positive electrode black nickel tab and the negative electrode black nickel tab respectively. The cylindrical battery cell was encapsulated with aluminum-plastic film, so that the two black nickel tabs were exposed from the positive electrode end of the battery, thus obtaining the cylindrical battery cell to be tested.

[0009] A container filled with liquid is provided. The container is placed on the platform of a weighing instrument. The cylindrical battery cell to be tested is immersed in the liquid with its bottom facing down, ensuring that the cylindrical battery cell does not touch the wall. The cylindrical battery cell to be tested is charged and discharged. The mass of the container filled with liquid is marked as m0, the mass of the cylindrical battery cell to be tested immersed in the liquid is marked as M, the density of the liquid is marked as ρ, and the formula for calculating the gas production V of the cylindrical battery cell to be tested is: V=(M–m0) / ρ.

[0010] The method for measuring the gas production of a cylindrical battery provided by this invention only requires drilling a hole in the positive electrode cap, wrapping the positive and negative nickel tabs with black adhesive, encapsulating the resulting cylindrical battery cell with an aluminum-plastic film, and immersing it in a container filled with liquid. By monitoring the mass change displayed by a weighing instrument before and after immersion, the gas production of the cylindrical battery under different conditions can be measured easily and quickly. This method is not only simple to operate, but also enables rapid and accurate testing of the gas production of cylindrical batteries. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the positive electrode cap after drilling, provided in an embodiment of the present invention;

[0012] Figure 2 This is a schematic diagram of a cylindrical battery cell to be tested after being encapsulated in aluminum-plastic film, as provided in an embodiment of the present invention.

[0013] Figure 3 This is a simulation diagram of the gas production testing device provided in an embodiment of the present invention. Detailed Implementation

[0014] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0015] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0016] Combination Figure 1-3 This invention provides a method for measuring the gas production of a cylindrical battery, comprising the following steps:

[0017] S01. Provide a cylindrical battery cell to be sealed and a positive electrode cap, and punch a hole in the positive electrode cap;

[0018] S02. The positive electrode cap, after being perforated, is used to seal the positive electrode of the cylindrical battery to be sealed, and the battery is assembled into a rough cylindrical battery cell product. Positive black glue nickel tabs and negative black glue nickel tabs are welded to the positive and negative electrodes of the rough cylindrical battery cell product, respectively, wherein the negative black glue nickel tabs extend to one end of the positive electrode.

[0019] S03. The positive electrode black adhesive nickel tab and the negative electrode black adhesive nickel tab are wrapped with high temperature resistant tape respectively, and the cylindrical battery cell is encapsulated with aluminum-plastic film, so that the two black adhesive nickel tabs are exposed from the positive end of the battery, thus obtaining the cylindrical battery cell to be tested.

[0020] S04. A container filled with liquid is provided. The container is placed on the platform of a weighing instrument. The cylindrical battery cell to be tested is immersed in the liquid with its bottom facing down, and the cylindrical battery cell to be tested does not touch the wall. The cylindrical battery cell to be tested is charged and discharged. The mass of the container filled with liquid is marked as m0, the mass of the cylindrical battery cell to be tested immersed in the liquid is marked as M, the density of the liquid is marked as ρ, and the formula for calculating the gas production V of the cylindrical battery cell to be tested is: V=(M–m0) / ρ.

[0021] The method for measuring the gas production of a cylindrical battery provided in this invention only requires punching a hole in the positive electrode cap, wrapping the positive and negative nickel tabs with black adhesive, encapsulating the resulting cylindrical battery cell with an aluminum-plastic film, and immersing it in a container filled with liquid. By monitoring the mass change displayed by a weighing instrument before and after immersion, the gas production of the cylindrical battery under different conditions can be measured easily and quickly. This method is not only simple to operate, but also enables rapid and accurate testing of the gas production of cylindrical batteries.

[0022] Specifically, in step S01 above, since the sealed space of a cylindrical battery is constructed with a steel shell, and the steel shell does not change with the internal volume, measuring the gas production is relatively complex. It is necessary to first release the internal gas, collect it, and then measure the gas production using an aluminum-plastic film that can characterize volume changes. Therefore, this embodiment of the invention uses a cylindrical battery cell to test the gas production of the corresponding cylindrical battery.

[0023] There are no strict limitations on the type of cylindrical battery; any conventional cylindrical battery can be used. Before sealing the cylindrical battery with a cap, a hole is drilled in the positive electrode cap to create a cavity. This cavity allows gas generated inside the battery to be guided out during testing and collected through the outer aluminum-plastic film of the packaging, thus enabling the measurement of gas production. The positive electrode cap after the perforation treatment is shown below. Figure 1 As shown.

[0024] In some embodiments, during the step of drilling holes in the positive electrode cap, the positive electrode cap is drilled with the welding positive electrode lug facing upwards, so as to form holes without affecting the overall shape of the positive electrode cap.

[0025] The size of the hole formed on the positive electrode cap should not be too large. If the hole is too large, leakage may occur during testing, thus affecting the accuracy of the test. Therefore, preferably, the diameter of the hole formed by the drilling process is 0.5~2mm.

[0026] Preferably, the hole is 1-10mm away from the center of the positive electrode cap to prevent the current cut-off device (CID) from flipping during the drilling process, which would cause the battery to malfunction.

[0027] In step S02 above, the positive electrode cap, after being perforated, is used to seal the positive electrode of the cylindrical battery to be sealed. This can be achieved using conventional methods. It is worth noting that before sealing, care must be taken to properly position the battery cells to prevent electrolyte leakage.

[0028] Positive and negative electrode tabs are welded to the positive and negative terminals of the cylindrical battery cell rough product, respectively. Since the aluminum-plastic film used in the subsequent cell encapsulation process has poor weldability to the cylindrical steel shell, the positive electrode tab in this embodiment of the invention is a positive black adhesive nickel tab, and the negative electrode tab is a negative black adhesive nickel tab.

[0029] In this embodiment of the invention, the welded negative electrode black adhesive nickel tab extends to one end of the positive electrode, so that the tab is exposed when measuring the exhaust volume, and the battery is then charged and discharged through the positive and negative electrodes. Therefore, the length of the positive electrode black adhesive nickel tab is greater than the length of the negative electrode black adhesive nickel tab, and the difference between the two is greater than or equal to the height of a cylindrical battery cell under test.

[0030] In some embodiments, the length of the positive electrode black adhesive nickel tab is 10-15 cm, and the length of the negative electrode black adhesive nickel tab is 15-20 cm. The length of the positive and negative tabs should preferably allow the black adhesive to be completely exposed at the positive end of the battery and sealed on the outer aluminum-plastic film of the packaging; more preferably, the lengths of the positive and negative tabs should be such that they are exposed and aligned at the positive end of the battery (i.e., the exposed lengths are consistent).

[0031] In step S03 above, since the positive electrode nickel tab is relatively long, to prevent misalignment and contact between the positive and negative electrodes during use, which could lead to a short circuit, this embodiment of the invention applies high-temperature resistant tape to the areas where the two tabs may come into contact to prevent the risk of a short circuit. As a more preferred embodiment, except for the exposed top of the tab (to facilitate external connection and normal charging and discharging of the battery), the other parts of the positive and negative electrodes are wrapped.

[0032] The high-temperature resistant tape is a highly viscous high-temperature resistant tape, which can effectively prevent short circuits. Simultaneously, the high-temperature resistant tape can withstand certain high-temperature conditions and does not melt under high-temperature conditions (greater than or equal to 120°C) (i.e., the high-temperature resistant tape is selected from high-temperature resistant tapes that do not melt at at least 120°C), thereby improving safety performance. In a preferred embodiment, the high-temperature resistant tape is selected from PI high-temperature adhesive and PET high-temperature adhesive. Preferably, the high-temperature resistant tape has excellent high-temperature resistance and good adhesion, effectively preventing short circuits.

[0033] Furthermore, the cylindrical battery cells are encapsulated using an aluminum-plastic film, sealing the cylindrical battery cells and preventing external water and oxygen from penetrating into the encapsulation bag formed by the aluminum-plastic film. The encapsulated cells are as follows: Figure 2 As shown.

[0034] In this embodiment of the invention, during the process of encapsulating the cylindrical battery cell with aluminum-plastic film, two black nickel tabs are exposed from the positive electrode end of the battery. Preferably, in the step of encapsulating the cylindrical battery cell with aluminum-plastic film and exposing the two black nickel tabs from the positive electrode end of the battery, the positive electrode black nickel tab and the negative electrode black nickel tab are aligned.

[0035] In step S04 above, the gas production of the cylindrical battery cell under test is tested using a gravimetric method. For example... Figure 3As shown in the embodiment of the invention, the method for testing the gas production of a cylindrical battery cell under test using the gravimetric method is as follows: A container filled with liquid is provided, the container is placed on the platform of a weighing instrument, and the cylindrical battery cell under test is immersed in the liquid with its bottom facing down, ensuring that the cylindrical battery cell does not touch the wall. The cylindrical battery cell under test is then charged and discharged. The mass of the container filled with liquid is marked as m0, the mass of the cylindrical battery cell under test immersed in the liquid is marked as M, the density of the liquid is marked as ρ, and the formula for calculating the gas production V of the cylindrical battery cell under test is: V = (M – m0) / ρ. The cylindrical battery cell under test can be fixed by a bracket, specifically by using a rope or similar means to tie the cylindrical battery cell under test, ensuring that it is fully immersed in the liquid without contacting the container, and preventing deformation or compression by the container.

[0036] Specifically, the testing principle is as follows: the force analysis of the container filled with liquid is performed to obtain the following formula (1), where F0 represents the supporting force on the container filled with liquid and g represents the gravitational acceleration;

[0037] m0g = F0(1)

[0038] After immersion in the battery cell, a force analysis was performed on the container, liquid, and battery cell as a whole, yielding the following equation (2), where F 拉 F1 represents the tension of the rope on the whole, F1 represents the supporting force on the whole, and m1 represents the weight of the cylindrical battery cell to be tested.

[0039] F 拉 + F1 = m0g + m1g(2)

[0040] Performing a stress analysis on the battery cell alone, we obtain the following equation (3), where F 浮 This represents the buoyancy force acting on the cylindrical battery cell under test.

[0041] F 拉 + F 浮 = m1g(3)

[0042] From (1)(2)(3), we can deduce: F 浮 = F1– F0

[0043] F1 and F0 can be directly weighed by a weighing instrument, i.e.: F1 = Mg, F0 = m0g;

[0044] Due to F 浮 = (M - m0) g(4)

[0045] And F 浮 = ρ·g·V 排 g(5)

[0046] Combining equations (4) and (5), we get: V = (M – m0) / ρ.

[0047] In a preferred embodiment, the liquid is selected from liquids with a density of less than or equal to 1 g / cm³. 3 A liquid with a known density. More preferably, the liquid is inexpensive and readily available water.

[0048] The following description is based on specific embodiments.

[0049] Example 1

[0050] A method for measuring the gas production of a cylindrical battery includes the following steps:

[0051] (1) Pre-treatment of cylindrical battery cap: With the reverse side (the side with the positive electrode tab welded) of the positive cap of the 26650 model 5.6Ah battery facing upwards, use a 1mm diameter drill bit to drill a hole 5mm away from the center of the positive cap. Figure 1 As shown.

[0052] (2) Cylindrical battery assembly process: After sealing the battery as described in step (1), cut out 11cm and 18cm long black glue nickel tabs, and weld them to the top of the positive electrode and the bottom of the negative electrode, respectively. Wrap the two tabs with 12mm high-temperature adhesive tape to prevent internal short circuits. After aligning the ends of the two black glue nickel tabs, seal them in a 20cm×20cm aluminum-plastic film. Figure 2 As shown.

[0053] (3) Cylindrical battery gas production test device: The assembled battery in (2) is placed in the gravimetric method. Figure 3 The testing procedures in the device are as follows:

[0054] a. First, weigh the beaker filled with water and let the weight be m0;

[0055] b. Next, hang the sealed battery cell with a string and immerse it in water. The weight obtained is M. At this point, the battery volume V can be calculated as V = (M – m0) / ρ 水 ,( ρ 水 = 1g / cm 3 The amount of gas produced by the battery is measured by the change in volume.

[0056] The gas production test data provided in Example 1 are shown in Table 1 below. The data shows that the test method is simple and has high accuracy.

[0057] Table 1

[0058]

[0059] Example 2

[0060] A method for measuring the gas production of a cylindrical battery includes the following steps:

[0061] (1) Pretreatment of cylindrical battery cap: With the reverse side (the side with the positive electrode tab welded) of the positive cap of the 26650 model 6.1Ah battery facing up, use a drill bit with a diameter of 1mm to drill a hole 5mm away from the center of the positive cap.

[0062] (2) Cylindrical battery assembly process: After sealing the battery described in step (1), cut out black glue nickel tabs with lengths of 11cm and 18cm, and weld them to the upper end of the positive electrode and the bottom of the negative electrode of the battery respectively. Wrap the two tabs with 12mm high temperature adhesive paper to prevent internal short circuit. After aligning the black glue of the two black glue nickel tabs, seal them in a 20cm×20cm aluminum-plastic film.

[0063] (3) Cylindrical battery gas production test device: The assembled battery in (2) is placed in the gravimetric method. Figure 3 The testing procedures in the device are as follows:

[0064] a. First, weigh the beaker filled with water and let the weight be m0;

[0065] b. Next, hang the sealed battery cell with a string and immerse it in water. The weight obtained is M. At this point, the battery volume V can be calculated as V = (M – m0) / ρ 水 , (ρ 水 = 1g / cm 3 The amount of gas produced by the battery is measured by the change in volume.

[0066] The gas production test data provided in Example 2 are shown in Table 2 below. The data shows that the test method is simple and has high accuracy.

[0067] Table 2

[0068]

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of measuring the gas production of a cylindrical battery, characterized by, The method comprises the following steps: providing a cylindrical battery cell to be sealed and a positive cap with a hole punched on the positive cap; sealing the positive electrode of the cylindrical battery to be sealed with the positive cap with a hole punched to assemble a cylindrical battery cell rough product, and welding a positive black rubber nickel tab and a negative black rubber nickel tab to the positive and negative electrodes of the cylindrical battery cell rough product respectively, wherein the negative black rubber nickel tab extends to one end of the positive electrode; wrapping the positive black rubber nickel tab and the negative black rubber nickel tab with high-temperature-resistant adhesive tape, and sealing the cylindrical battery cell with an aluminum plastic film to seal the cylindrical battery cell, isolate water and oxygen in the outside from entering the sealed bag formed by the aluminum plastic film, collect the gas generated in the battery during the test through the outer packaging aluminum plastic film, and make the two black rubber nickel tabs exposed from one end of the positive electrode of the battery to obtain a cylindrical battery cell to be tested; providing a container containing liquid, placing the container on the loading platform of a weighing instrument, immersing the cylindrical battery cell to be tested with the bottom facing down in the liquid, and the cylindrical battery cell to be tested does not touch the wall, and charging and discharging the cylindrical battery to be tested, wherein the mass of the container containing liquid is marked as m0, the mass of the cylindrical battery cell to be tested immersed in the liquid is marked as M, the density of the liquid is marked as p, and the calculation formula of the gas production V of the cylindrical battery cell to be tested is: V=(M-m0) / p.

2. The method of measuring the gas production of a cylindrical battery of claim 1, wherein, In the step of punching a hole on the positive cap, the side of the positive cap with the welded positive tab is upward, and the positive cap is punched.

3. The method of claim 2, wherein the measurement of the amount of gas produced by the cylindrical battery is performed by a method comprising: The diameter of the hole formed by the punching process is 0.5-2mm.

4. The method of claim 3, wherein the measurement of the amount of gas produced by the cylindrical battery is performed by a method comprising: The hole is 1-10mm away from the center of the positive cap.

5. The method of measuring the gas production of a cylindrical battery according to any one of claims 1 to 4, wherein The length of the positive black rubber nickel tab is greater than the length of the negative black rubber nickel tab, and the difference between them is greater than or equal to the height of one cylindrical battery cell to be tested.

6. The method of measuring the gas production of a cylindrical battery of claim 5, wherein, The length of the positive black rubber nickel tab is 10-15cm, and the length of the negative black rubber nickel tab is 15-20cm.

7. The method of measuring the gas production of a cylindrical battery according to any one of claims 1 to 4, wherein The high-temperature-resistant adhesive tape is selected from at least high-temperature-resistant adhesive tapes that do not melt at a temperature of 120℃.

8. The method of measuring the gas production of a cylindrical battery of claim 7, wherein, The high-temperature-resistant adhesive tape is selected from one of PI high-temperature-resistant adhesive tape and PET high-temperature-resistant adhesive tape.

9. The method of measuring the gas production of a cylindrical battery according to any one of claims 1 to 4, wherein said liquid is selected from the group of liquids having a density less than or equal to 1 g / cm 3 .

10. The method of measuring the gas production of a cylindrical battery according to any one of claims 1 to 4, wherein In the step of sealing the cylindrical battery cell with an aluminum plastic film and making the two black rubber nickel tabs exposed from one end of the positive electrode of the battery, the positive black rubber nickel tab and the negative black rubber nickel tab are flush.

Images