A battery thermal runaway key parameter testing method and system

Abstract

The application discloses a kind of battery thermal runaway key parameter test method and system, method includes: battery is fully charged and records the thickness between two big faces thereof;Battery is placed in fixture and records the thickness of insulating plate arranged by the face of fixture relative to battery;Adjust the spacing of fixture, obtain the maximum deformation of battery relative to its thickness direction;Battery and fixture are placed in oven and thermal runaway test is carried out;If multiple sets of tests of the same deformation exist at least one battery explosion, then the deformation is the critical deformation of the battery thermal runaway, adjust the fixture, reduce the deformation allowed by battery by preset ratio, and then carry out multiple sets of tests, if battery does not explode, then this deformation is the maximum deformation allowed by battery thermal runaway;The application has the advantages that the maximum deformation allowed by battery thermal runaway is obtained, which is helpful for accurate judgment of battery thermal runaway in practical application, and safety accidents such as battery explosion are avoided.

Description

Technical Field

[0001] This invention relates to the field of battery testing technology, specifically to a method and system for testing key parameters of battery thermal runaway. Background Technology

[0002] Battery thermal runaway is the core of battery safety issues. Generally, a battery may explode when not subjected to thermal runaway testing with a clamp. When a battery is subjected to thermal runaway testing with a clamp, it will not explode. The clamp limits the expansion of the battery casing, and the spacing of the clamps determines the amount of battery deformation. For a battery, the amount of deformation during thermal runaway must be within a certain range to prevent explosion; that is, there is a maximum allowable deformation for battery thermal runaway. Current technologies focus on solutions for battery thermal runaway protection or monitoring. For example, the battery thermal runaway protection system and method disclosed in Chinese Patent Publication No. CN115911625A primarily aims to provide early warning of thermal runaway and take cooling measures before thermal runaway occurs, thus avoiding accidents such as fires and explosions caused by battery thermal runaway. Another example is the lithium-ion battery thermal runaway monitoring system and method disclosed in Chinese Patent Publication No. CN113311342A, which monitors whether the battery has experienced thermal runaway based on the deformation state of individual battery cells, achieving low-cost and high-reliability monitoring of battery thermal runaway. The maximum permissible deformation for battery thermal runaway is a key parameter. Monitoring this parameter helps in accurately assessing the extent of thermal runaway. By detecting the deformation, batteries exceeding the maximum permissible deformation can be eliminated, ensuring operational safety and preventing accidents such as battery explosions. However, there is currently no reliable method to confirm the maximum permissible deformation for battery thermal runaway. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for testing key parameters of battery thermal runaway, and to obtain the maximum allowable deformation of battery thermal runaway.

[0004] This invention solves the above-mentioned technical problems through the following technical means: a method for testing key parameters of battery thermal runaway, comprising the following steps: Step 1: Fully charge the battery and record the thickness between its two large surfaces; Step 2: Place the battery in the fixture and record the thickness of the insulating plate on the side of the fixture facing the battery; Step 3: Adjust the spacing of the fixtures to obtain the maximum deformation of the battery relative to its thickness direction; Step 4: Place the fixture and battery in a temperature chamber for thermal runaway testing; Step 5: If at least one battery explodes in multiple tests with the same deformation amount, then the deformation amount is the critical deformation amount for thermal runaway of the battery. Adjust the fixture and reduce the allowable deformation amount of the battery according to the preset ratio, and then conduct multiple tests. If none of the batteries explode, then this deformation amount is the maximum allowable deformation amount for thermal runaway of the battery.

[0005] Further, step one includes: Charge the battery with a constant current and constant voltage of 0.4C~0.6C until the cutoff voltage, and record the thickness D between its two large surfaces.

[0006] Furthermore, step two includes: Wrap the positive and negative tabs of the battery with plastic film, place the battery in a fixture, and wrap an insulating plate around the two large surfaces of the battery facing the fixture. Measure and record the thickness d of the insulating plate.

[0007] Furthermore, the insulating board is made of Teflon or epoxy resin.

[0008] Furthermore, step three includes: Adjust the clamp spacing H, confirm the spacing, and then fix the clamp. Under this condition, determine the maximum deformation of the battery relative to its thickness direction. .

[0009] Furthermore, step four includes: The fixture and battery are placed in a temperature chamber, which is heated to a temperature T at a preset rate. Temperature T is greater than the rupture temperature of the battery separator. The temperature is maintained at this ambient temperature for a preset time to confirm the thermal runaway test results of the battery in the temperature chamber.

[0010] Furthermore, the preset temperature rise rate is in the range of 4~6℃ / min.

[0011] Furthermore, the preset time is more than two hours.

[0012] Furthermore, step five includes: If, in three sets of tests with the same deformation amount, one or two batteries explode, then the deformation amount is the critical deformation amount for thermal runaway of that battery. Adjust the fixture to reduce the deformation amount to 90% of the above deformation amount, and perform three more sets of tests. If the batteries still explode, continue to adjust the fixture to reduce the deformation amount to 90% of the previous deformation amount, and perform three more sets of tests until none of the batteries explode. This deformation amount is the maximum allowable deformation amount for thermal runaway of that battery.

[0013] This invention also provides a battery thermal runaway key parameter testing system, comprising: The first thickness measurement module is used to fully charge the battery and record the thickness between its two large surfaces; The second thickness measurement module is used to place the battery in the fixture and record the thickness of the insulating plate set on the surface of the fixture relative to the battery. The deformation determination module is used to adjust the spacing of the fixtures and obtain the maximum deformation of the battery relative to its thickness direction. Thermal runaway test module, used to place the fixture and battery in a temperature chamber for thermal runaway testing; The key parameter acquisition module is used to determine the critical deformation amount of a battery in case at least one battery explodes in multiple tests with the same deformation amount. The module adjusts the fixture to reduce the allowable deformation amount of the battery by a preset ratio and then performs multiple tests. If none of the batteries explode, the deformation amount is the maximum allowable deformation amount for thermal runaway of the battery.

[0014] Furthermore, the first thickness measurement module is also used for: Charge the battery with a constant current and constant voltage of 0.4C~0.6C until the cutoff voltage, and record the thickness D between its two large surfaces.

[0015] Furthermore, the second thickness measurement module is also used for: Wrap the positive and negative tabs of the battery with plastic film, place the battery in a fixture, and wrap an insulating plate around the two large surfaces of the battery facing the fixture. Measure and record the thickness d of the insulating plate.

[0016] Furthermore, the insulating board is made of Teflon or epoxy resin.

[0017] Furthermore, the deformation determination module is also used for: Adjust the clamp spacing H, confirm the spacing, and then fix the clamp. Under this condition, determine the maximum deformation of the battery relative to its thickness direction. .

[0018] Furthermore, the thermal runaway testing module is also used for: The fixture and battery are placed in a temperature chamber, which is heated to a temperature T at a preset rate. Temperature T is greater than the rupture temperature of the battery separator. The temperature is maintained at this ambient temperature for a preset time to confirm the thermal runaway test results of the battery in the temperature chamber.

[0019] Furthermore, the preset temperature rise rate is in the range of 4~6℃ / min.

[0020] Furthermore, the preset time is more than two hours.

[0021] Furthermore, the key parameter acquisition module is also used for: If, in three sets of tests with the same deformation amount, one or two batteries explode, then the deformation amount is the critical deformation amount for thermal runaway of that battery. Adjust the fixture to reduce the deformation amount to 90% of the above deformation amount, and perform three more sets of tests. If the batteries still explode, continue to adjust the fixture to reduce the deformation amount to 90% of the previous deformation amount, and perform three more sets of tests until none of the batteries explode. This deformation amount is the maximum allowable deformation amount for thermal runaway of that battery.

[0022] The advantages of this invention are: (1) This invention obtains the critical deformation amount of battery thermal runaway by conducting multiple thermal runaway tests with the same deformation amount. Then, based on this, the fixture is adjusted and the allowable deformation amount of the battery is reduced by a preset ratio and the test is repeated to obtain the maximum allowable deformation amount of battery thermal runaway. The test results are intuitive and reliable. In practical applications, this helps to accurately judge the battery thermal runaway situation and avoid safety accidents such as battery explosion.

[0023] (2) This invention controls the deformation of the battery by adjusting the spacing between the clamps, making it easy to operate. Due to the spacing between the clamps, if a traditional heating film is used to trigger thermal runaway of the battery, the heating film may not be fixed and may fall off during the heating process, preventing the battery from successfully triggering thermal runaway. This invention triggers thermal runaway by heating in a hot box, which can stably trigger thermal runaway of the battery. The maximum allowable deformation of the battery during thermal runaway is confirmed by the thermal runaway test results of the battery in clamps with different spacing. The test results are intuitive and reliable. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for testing key parameters of battery thermal runaway as disclosed in an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating the installation relationship between the fixture and the battery in a battery thermal runaway key parameter testing method disclosed in an embodiment of the present invention. Figure 3 The images show a comparison of battery photographs after testing for 35% and 31.5% deformation amounts, as disclosed in the battery thermal runaway key parameter testing method of this invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0026] Example 1 like Figure 1As shown, this invention provides a method for testing key parameters of battery thermal runaway, comprising the following steps: S1: Charge battery 1 to full charge according to the charging method provided by the supplier, that is, charge battery 1 to the cutoff voltage at a constant current and constant voltage of 0.4C~0.6C, and record the thickness D between its two large surfaces.

[0027] S2: Wrap the positive and negative tabs of battery 1 with plastic film to prevent the tabs from directly contacting the metal clamp 2 and causing a short circuit; place battery 1 in clamp 2, the base material of clamp 2 is steel, and the steel clamp 2 is wrapped with Teflon or epoxy board or other insulating materials on the side close to battery 1 to prevent the tabs from directly contacting the metal clamp 2 and causing a short circuit; measure and record the thickness d of the Teflon or epoxy board, i.e. the insulating board 3, used on one side of clamp 2. S3: Adjust the spacing H of clamp 2. After confirming the spacing, use bolts and nuts to fix clamp 2. Under this condition, the maximum deformation of battery 1 relative to the thickness of battery 1 is... ; S4: Place clamp 2 and battery 1 in a temperature chamber. The temperature chamber is heated to temperature T at a rate of 5℃ / min. Temperature T should be greater than the membrane rupture temperature of the battery 1. Maintain this temperature for more than two hours to confirm the thermal runaway test results of battery 1 in the temperature chamber. S5: If 1-2 batteries 1 explode in 3 sets of tests with the same deformation amount, then the deformation amount is the critical deformation amount for thermal runaway of battery 1; adjust the clamp 2 to make the deformation amount 90% of the above deformation amount, and perform 3 sets of tests again. If battery 1 still explodes, continue to adjust the clamp 2 to make the deformation amount 90% of the previous deformation amount, and perform 3 sets of tests again until battery 1 does not explode. Then this deformation amount is the maximum allowable deformation amount for thermal runaway of battery 1.

[0028] To more clearly explain the process of this invention, a specific simulation example is given below: S1: Battery 1 is charged to 3.65V using a 0.5C constant current and constant voltage method. The thickness between the two large surfaces of battery 1 is measured and recorded as D=53mm.

[0029] S2: Wrap the positive and negative tabs of battery 1 with plastic film to prevent the tabs from directly contacting the metal clamp 2 and causing a short circuit; place battery 1 in clamp 2, the base material of clamp 2 is steel, and the steel clamp 2 is wrapped with Teflon or epoxy board or other insulating materials on the side near battery 1 to prevent the tabs from directly contacting the metal clamp 2 and causing a short circuit; measure and record the thickness d of the Teflon or epoxy board, i.e. the insulating board 3, used on one side of clamp 2; in this embodiment, d=0.2mm.

[0030] S3: Adjust the spacing H of clamp 2 to 72mm. After confirming the spacing, use bolts and nuts to fix clamp 2. The schematic diagram of clamp 2 is shown below. Figure 2As shown, under this condition, the maximum deformation of battery 1 relative to its thickness is B = 100%. (HD-2d) / D=100% (72-53-2 0.2) / 53=35%.

[0031] S4: Place clamp 2 and battery 1 in a temperature chamber. The temperature chamber is raised to T=200℃ at a rate of 5℃ / min. T=200℃ is higher than the membrane rupture temperature of battery 1 (170℃). Maintain this temperature for 3 hours. In 3 sets of tests with 35% deformation, 2 batteries 1 exploded, and 1 battery 1 did not explode. The photos after the test are shown below. Figure 3 As shown.

[0032] S5: Adjust clamp 2 to reduce the deformation to 90% of the aforementioned deformation, i.e., 31.5%. Calculations show that the clamp spacing at this point is 70.1mm. Adjust the clamp spacing to 70.1mm and perform three more tests. None of the three batteries exploded. The photos after the tests are shown below. Figure 3 As shown, the deformation of 31.5% is the maximum allowable deformation for thermal runaway of battery 1.

[0033] Through the above technical solutions, this invention obtains the critical deformation amount of battery 1 for thermal runaway by conducting multiple sets of thermal runaway tests with the same deformation amount. Then, based on this, the fixture 2 is adjusted to reduce the allowable deformation amount of battery 1 by a preset ratio and the test is repeated to obtain the maximum allowable deformation amount of battery 1 for thermal runaway. The test results are intuitive and reliable, and in practical applications, they help to accurately judge the thermal runaway situation of battery 1 and avoid safety accidents such as battery 1 explosion.

[0034] Example 2 Based on Embodiment 1, Embodiment 2 of the present invention also provides a battery thermal runaway key parameter testing system, comprising: The first thickness measurement module is used to fully charge battery 1 and record the thickness between its two large surfaces; The second thickness measurement module is used to place the battery 1 in the clamp 2 and record the thickness of the insulating plate 3 set on the side of the clamp 2 relative to the battery 1. The deformation determination module is used to adjust the spacing of the clamps 2 and obtain the maximum deformation of the battery 1 relative to its thickness direction. The thermal runaway test module is used to place the clamp 2 and the battery 1 in a temperature chamber for thermal runaway testing; The key parameter acquisition module is used to determine the thermal runaway critical deformation amount of battery 1 if at least one battery 1 explodes in multiple sets of tests with the same deformation amount. The module adjusts the fixture 2 to reduce the allowable deformation amount of battery 1 by a preset ratio, and then performs multiple sets of tests. If none of the batteries 1 explode, the deformation amount is the maximum allowable deformation amount for thermal runaway of battery 1.

[0035] Specifically, the first thickness measurement module is also used for: Battery 1 was charged to the cutoff voltage at a constant current and constant voltage of 0.4C~0.6C, and the thickness D between its two large surfaces was recorded.

[0036] More specifically, the second thickness measurement module is also used for: Wrap the positive and negative tabs of battery 1 with plastic film, place battery 1 in clamp 2, and wrap the clamp 2 with insulating plate 3 on the two large surfaces of battery 1. Measure and record the thickness d of insulating plate 3.

[0037] More specifically, the insulating plate 3 is made of Teflon or epoxy resin.

[0038] More specifically, the deformation determination module is also used for: Adjust the spacing H of clamp 2, confirm the spacing, and then fix clamp 2. Under this condition, the maximum deformation of battery 1 relative to the thickness direction of battery 1 is... .

[0039] More specifically, the thermal runaway test module is also used for: The clamp 2 and battery 1 are placed in a temperature chamber, which is heated to a temperature T at a preset temperature rise rate. The temperature T is greater than the membrane rupture temperature of the battery 1. The temperature is maintained at this ambient temperature for a preset time to confirm the thermal runaway test results of battery 1 in the temperature chamber.

[0040] More specifically, the preset temperature rise rate is in the range of 4~6℃ / min.

[0041] More specifically, the preset time is two hours or more.

[0042] More specifically, the key parameter acquisition module is also used for: If, in three sets of tests with the same deformation amount, one or two batteries 1 explode, then the deformation amount is the critical deformation amount for thermal runaway of battery 1. Adjust the clamp 2 to reduce the deformation amount to 90% of the above deformation amount, and perform three sets of tests again. If battery 1 still explodes, continue to adjust the clamp 2 to reduce the deformation amount to 90% of the previous deformation amount, and perform three sets of tests again until none of battery 1 explodes. Then this deformation amount is the maximum allowable deformation amount for thermal runaway of battery 1.

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing key parameters of battery thermal runaway, characterized in that, Includes the following steps: Step 1: Fully charge the battery and record the thickness between its two large surfaces; Step 2: Place the battery in the fixture and record the thickness of the insulating plate on the side of the fixture facing the battery; Step 3: Adjust the spacing of the fixtures to obtain the maximum deformation of the battery relative to its thickness direction; Step 4: Place the fixture and battery in a temperature chamber for thermal runaway testing; Step 5: If at least one battery explodes in multiple tests with the same deformation amount, then the deformation amount is the critical deformation amount for thermal runaway of the battery. Adjust the fixture and reduce the allowable deformation amount of the battery according to the preset ratio, and then conduct multiple tests. If none of the batteries explode, then this deformation amount is the maximum allowable deformation amount for thermal runaway of the battery.

2. The method for testing key parameters of battery thermal runaway according to claim 1, characterized in that, Step one includes: Charge the battery with a constant current and constant voltage of 0.4C~0.6C until the cutoff voltage, and record the thickness D between its two large surfaces.

3. The method for testing key parameters of battery thermal runaway according to claim 2, characterized in that, Step two includes: Wrap the positive and negative tabs of the battery with plastic film, place the battery in a fixture, and wrap an insulating plate around the two large surfaces of the battery facing the fixture. Measure and record the thickness d of the insulating plate.

4. The method for testing key parameters of battery thermal runaway according to claim 3, characterized in that, The insulating board is made of Teflon or epoxy resin.

5. The method for testing key parameters of battery thermal runaway according to claim 3, characterized in that, Step three includes: Adjust the clamp spacing H, confirm the spacing, and then fix the clamp. Under this condition, determine the maximum deformation of the battery relative to its thickness direction. .

6. The method for testing key parameters of battery thermal runaway according to claim 5, characterized in that, Step four includes: The fixture and battery are placed in a temperature chamber, which is heated to a temperature T at a preset rate. Temperature T is greater than the rupture temperature of the battery separator. The temperature is maintained at this ambient temperature for a preset time to confirm the thermal runaway test results of the battery in the temperature chamber.

7. The method for testing key parameters of battery thermal runaway according to claim 6, characterized in that, The preset temperature rise rate is in the range of 4~6℃ / min.

8. The method for testing key parameters of battery thermal runaway according to claim 6, characterized in that, The preset time is two hours or more.

9. The method for testing key parameters of battery thermal runaway according to claim 6, characterized in that, Step five includes: If, in three sets of tests with the same deformation amount, one or two batteries explode, then the deformation amount is the critical deformation amount for thermal runaway of that battery. Adjust the fixture to reduce the deformation amount to 90% of the above deformation amount, and perform three more sets of tests. If the batteries still explode, continue to adjust the fixture to reduce the deformation amount to 90% of the previous deformation amount, and perform three more sets of tests until none of the batteries explode. This deformation amount is the maximum allowable deformation amount for thermal runaway of that battery.

10. A battery thermal runaway key parameter testing system, characterized in that, include: The first thickness measurement module is used to fully charge the battery and record the thickness between its two large surfaces; The second thickness measurement module is used to place the battery in the fixture and record the thickness of the insulating plate set on the surface of the fixture relative to the battery. The deformation determination module is used to adjust the spacing of the fixtures and obtain the maximum deformation of the battery relative to its thickness direction. Thermal runaway test module, used to place the fixture and battery in a temperature chamber for thermal runaway testing; The key parameter acquisition module is used to determine the critical deformation amount of a battery in case at least one battery explodes in multiple tests with the same deformation amount. The module adjusts the fixture to reduce the allowable deformation amount of the battery by a preset ratio and then performs multiple tests. If none of the batteries explode, the deformation amount is the maximum allowable deformation amount for thermal runaway of the battery.

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