Method for detecting battery swelling force distribution, device and cell clamp adjustment method

Abstract

The present application relates to the method for detecting battery expansion force distribution, device and cell clamp adjustment method, including the following steps: using two prepared clamps to clamp the battery to be detected, then using the locking component between the two clamps to make the two clamps apply clamping force to the battery, wherein the clamp is prepared by mixing force luminescent material and transparent epoxy resin material with set quality ratio; the light intensity of the multiple regions divided by the corresponding clamp part of the battery is tested, and the battery expansion force distribution is obtained through the light intensity test result, the detection efficiency is improved by using the detection method of the present application, and the detection time is reduced.

Description

Technical Field

[0001] This invention relates to the field of battery testing technology, specifically to a method, apparatus, and cell clamp adjustment method for detecting the distribution of battery expansion force. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] The expansion force of lithium-ion batteries during charge-discharge cycles has a crucial impact on their cycle performance. To avoid the adverse effects of gas generation and electrode expansion during charge-discharge cycles, clamps are typically applied to both sides of the battery for pressure fixation. To ensure uniform stress on the entire cell, the same torque is usually applied to the fixing bolts of the clamps. Current technology uses pressure sensors to measure the expansion force of the cell, but this method can only measure the overall expansion force of the cell and cannot accurately measure the expansion force at a specific location. Furthermore, the device structure is very complex and costly.

[0004] Chinese patent application CN118882876A discloses a battery module expansion force measuring device and expansion force distribution testing method. Utilizing the special properties of fluorescent materials, a fluorescent solution is uniformly coated on the surface of the battery cell in the battery module. When the battery cell in the battery module expands, the film of fluorescent material will emit light under the excitation of a specific light source when subjected to force. The fluorescent image is acquired and recorded by a CCD camera system, thus obtaining the distribution of expansion force on the surface of the module.

[0005] However, in the technical solutions of the above patent applications, if the expansion force distribution test is performed on multiple cells, each cell needs to be coated with fluorescent material and wait for film formation, which greatly consumes the test time and reduces work efficiency. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method, apparatus, and cell clamp adjustment method for detecting the distribution of battery expansion force, which greatly shortens the testing time and improves testing efficiency when testing the expansion force of multiple cells.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] In a first aspect, embodiments of the present invention provide a method for detecting the distribution of battery expansion force, comprising the following steps:

[0009] The battery cell to be tested is clamped by two pre-prepared clamps, and then the clamping component between the two clamps is used to apply clamping force to the battery cell. The clamps are made of a mixture of mechanoluminescent material and epoxy resin material in a set mass ratio.

[0010] The luminous intensity of multiple regions divided by the corresponding clamping plate of the battery cell is tested, and the distribution of the battery cell expansion force is obtained from the luminous intensity test results.

[0011] Optionally, the preparation method of the clamp is as follows: mix and stir a set mass ratio of mechanoluminescent material and transparent epoxy resin, then pour it into a mold for high-temperature curing, and obtain the clamp after demolding.

[0012] Optionally, the curing temperature of the high-temperature curing is 120℃-160℃, and the curing time is greater than 24 hours.

[0013] Optional: The mass ratio between the metronic material and the epoxy resin is set to 1:5-1:10.

[0014] Optionally, the mesophilic material is SrAl2O4:Ce 3+ Or SrAl2O4:Eu 2+ Or BaSi2O2N2: Eu 2+ Or ZnS:Cu 2+ Or CaAl2Si2O8:Eu 2+ Or tetraphenylethylene derivatives or organometallic complexes.

[0015] Optionally, the locking component uses bolts and nuts. The four corners of the two clamping plates are provided with through holes that match the bolt shank. After the bolt passes through the through holes of the two clamping plates, the nut is threaded on and tightened. The head of the bolt and the nut together use the clamping plates to apply clamping force to the battery cell.

[0016] Optionally, a fiber optic spectrometer can be used to test the luminescence intensity of multiple areas of the clamp.

[0017] Secondly, embodiments of the present invention provide an apparatus for detecting the distribution of battery expansion force, including multiple locking components, two clamping plates, and a light intensity testing device. The clamping plates are prepared by mixing a mechanoluminescent material and an epoxy resin material in a set mass ratio. The locking components can cooperate with the clamping plates to apply a clamping force to the battery cell between the two clamping plates.

[0018] Optionally, the locking component uses bolts and nuts. The four corners of the two clamping plates are provided with through holes that match the bolt shank. After the bolt passes through the through holes of the two clamping plates, the nut is threaded on and tightened. The head of the bolt and the nut together use the clamping plates to apply clamping force to the battery cell.

[0019] Thirdly, embodiments of the present invention provide a method for adjusting a battery cell clamp, comprising the following steps:

[0020] The method for detecting the distribution of battery expansion force described in the first aspect is used to detect the distribution of expansion force in the battery cell;

[0021] If the difference in luminous intensity between any two regions divided by the clamping plate is not greater than the set value, the original torque force is applied to the actual clamp to fix the battery. If there are two regions where the difference in luminous intensity is greater than the set value, the locking component between the two clamping plates is adjusted until the difference in luminous intensity between any two regions obtained by the method for detecting the distribution of battery expansion force as described in the first aspect is not greater than the set value. The new torque force applied to the locking component is recorded, and the new torque force is applied to the actual clamp to fix the battery.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. The present invention provides a method for detecting the distribution of battery expansion force. The expansion force of the battery is detected by measuring the light intensity in various regions of a clamp containing a luminescent material. This method can obtain the distribution of battery expansion force in different regions. The clamp is prefabricated and can be reused for testing different battery cells. Compared to the requirement of coating each battery cell with fluorescent material for testing multiple battery cells, this method greatly shortens the testing time and improves the testing efficiency.

[0024] 2. The method for detecting the distribution of battery expansion force in this invention uses a fiber optic spectrometer to detect light intensity, which can obtain quantitative detection results of light intensity. This allows for an accurate assessment of the uniformity of the battery expansion force distribution, facilitating subsequent adjustment of the battery clamps and extending the battery's service life.

[0025] 3. The method for detecting the distribution of battery expansion force in this invention uses a clamping plate with a locking component to perform the detection, which is consistent with the actual fixing conditions of the battery. It can completely simulate the fixing of the battery under actual working conditions and has better guiding significance for the subsequent adjustment of the battery clamp. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0027] Figure 1 This is a flowchart of the method in Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of Embodiment 2 of the present invention;

[0029] Figure 3 This is a curve showing the fitting relationship between force and luminescence intensity in the verification test of this invention;

[0030] Figure 4This is a schematic diagram of the cell division area in the verification test of this invention;

[0031] Figure 5 This is a graph of cell cycle data from the verification test of this invention;

[0032] Among them, 1. battery cell, 2. clamp, 3. fiber optic spectrometer, 4. signal display;

[0033] 21. Clamping plate, 22. Bolt, 23. Nut. Detailed Implementation

[0034] Example 1

[0035] This embodiment provides a method for detecting the distribution of battery expansion force, such as... Figure 1 As shown, it includes the following steps:

[0036] Step 1: Prepare the test fixture in advance. The fixture includes two clamping plates and multiple locking components.

[0037] In this embodiment, the shape and size of the clamping plate match the battery cell, which has dimensions of 52*148*110mm. Therefore, the clamping plate has a length of 160mm, a height of 120mm, and a thickness of 20mm. The locking components use bolts and nuts, with bolts having a diameter of 10mm. Correspondingly, each of the four corners of the two clamping plates has through holes for the bolt shanks to pass through. The clamping plate is prepared by mixing a mechanoluminescent material and an epoxy resin material in a predetermined mass ratio. The preparation method is as follows:

[0038] The specific preparation method of the clamping plate is as follows:

[0039] Step 1.1: Mix the metronome material and transparent epoxy resin in the specified mass ratio until homogeneous.

[0040] The mass ratio of the mechanoluminescent material to the epoxy resin is 1:5 to 1:10. In this embodiment, the mass ratio of the mechanoluminescent material to the epoxy resin is 1:5.

[0041] The mechanoluminescent material is SrAl2O4:Ce 3+ Or SrAl2O4:Eu 2+ Or BaSi2O2N2: Eu 2+ Or ZnS:Cu 2+ Or CaAl2Si2O8:Eu 2+ Alternatively, tetraphenylethylene derivatives or organometallic complexes may be used. In this embodiment, the metheluminescent material is CaAl2Si2O8:Eu 2+ .

[0042] CaAl2Si2O8:Eu2+ Mix the metronic material with epoxy resin at a mass ratio of 1:5 and stir for 30-60 minutes to ensure that the metronic material is evenly dispersed in the epoxy resin.

[0043] Step 1.2: Pour the liquid obtained in Step 1.1 into the mold and cure it at high temperature in an oven to form a fixture of a specific shape.

[0044] The curing temperature for high-temperature curing is 120℃-160℃, and the curing time is greater than 24 hours. In this embodiment, curing is carried out in an oven at 150℃ for 36 hours.

[0045] Step 1.3: After curing, demold to obtain a clamping plate. Then, according to the bolt diameter, drill holes at the four corners of the clamping plate using machining to obtain through holes for the bolts to pass through.

[0046] Step 2: Place the battery cell to be tested between the two clamping plates, then pass bolts through the four corners of the clamping plates and tighten the nuts. By controlling the torque force, the two clamping plates apply a clamping force of 150±10 kgf to the battery cell. At this time, the CaAl2Si2O8:Eu dispersed in the epoxy resin... 2+ When subjected to pressure, it emits blue light. The intensity of the light emission can be observed with the naked eye at various points on the clamp. The stronger the light emission, the greater the pressure.

[0047] Step 3: Divide the clamping plate part corresponding to the battery cell into multiple regions, and use a fiber optic spectrometer to further test the light intensity of each region. Point the signal receiver of the fiber optic spectrometer at the corresponding region, receive the light signal of the corresponding region and test the light intensity, and record it to obtain the distribution of the battery cell expansion force for evaluation.

[0048] In this embodiment, if the difference in luminous intensity obtained from testing any two regions is not greater than a set value, the expansion force of the battery cell is considered to be uniformly distributed.

[0049] Furthermore, the set value is 50, and it is understood that those skilled in the art can set the size of the set value according to actual needs.

[0050] After the test is completed, the bolts and nuts are removed, and the clamping plate is relieved of the compressive force, returning it to its initial state, so that the next test on the distribution of cell expansion force can be carried out.

[0051] The detection method of this embodiment detects the expansion force of the battery by measuring the light intensity in various regions of a clamp containing a luminescent material. This allows for the acquisition of the distribution of the battery expansion force in different regions. Furthermore, the clamp is prefabricated and can be reused for testing different battery cells. Compared to the requirement of coating each cell with fluorescent material for testing multiple cells, this method significantly shortens the testing time and improves efficiency. The method uses bolts and nuts to clamp the battery cells, which is consistent with the actual fixing conditions of the battery and can completely simulate the fixing of the battery under actual working conditions. This provides better guidance for the subsequent adjustment of the battery clamp.

[0052] In this embodiment, a fiber optic spectrometer is used to reflect the expansion force of the battery cell through the light intensity, which can obtain the detection results of light intensity quantification. This allows for an accurate assessment of the uniformity of the battery expansion force distribution, which is convenient for subsequent adjustment of the battery clamps. This ensures that the battery cell is subjected to uniform force at the initial stage of cycling, avoids the problem of rapid cycle failure caused by uneven force, and extends the battery's service life.

[0053] Example 2

[0054] This embodiment provides a device for detecting the distribution of battery expansion force, such as... Figure 2 As shown, the device includes a clamp 2 and a luminous intensity detection device. The clamp 2 is used to apply clamping force to the battery cell, and the luminous intensity detection device is used to detect the luminous intensity of each area of ​​the clamp. The clamp includes two clamping plates 21 and four sets of locking components. The clamping plates 21 are rectangular plates with a length of 160mm, a height of 120mm, and a thickness of 20mm. The locking components are bolts 22 and nuts 23. Preferably, the bolts 22 are bolts with a diameter of 10mm. Correspondingly, the four corners of the clamping plates 21 are provided with through holes that match the spiral.

[0055] The clamping plate 21 is prepared by mixing a mechanoluminescent material and an epoxy resin material in a predetermined mass ratio, and the preparation method is as follows:

[0056] Step 1.1: Mix the metronome material and epoxy resin in the specified mass ratio until homogeneous.

[0057] The mass ratio of the mechanoluminescent material to the epoxy resin is 1:5 to 1:10. In this embodiment, the mass ratio of the mechanoluminescent material to the epoxy resin is 1:5.

[0058] The mechanoluminescent material is SrAl2O4:Ce 3+ Or SrAl2O4:Eu 2+ Or BaSi2O2N2: Eu 2+ Or ZnS:Cu 2+Or CaAl2Si2O8:Eu 2+ Alternatively, tetraphenylethylene derivatives or organometallic complexes may be used. Existing mechanoluminescent materials can be employed; in this embodiment, the mechanoluminescent material is CaAl₂Si₂O₈:Eu. 2+ .

[0059] CaAl2Si2O8:Eu 2+ Mix the metronic material with epoxy resin at a mass ratio of 1:5 and stir for 30-60 minutes to ensure that the metronic material is evenly dispersed in the epoxy resin.

[0060] Step 1.2: Pour the liquid obtained in Step 1.1 into the mold and cure it at high temperature in an oven.

[0061] The high-temperature curing process involves a curing temperature of 120℃-160℃ and a curing time greater than 24 hours. In this embodiment, curing is carried out in an oven at 150℃ for 36 hours. The mold can be designed according to the shape and size of the clamping plate, using existing technology, and will not be described in detail here.

[0062] Step 1.3: After curing, demold to obtain clamping plate 21. Then, according to the diameter of bolt 22, drill holes at the four corners of clamping plate 21 using mechanical processing to obtain through holes for bolt 22 to pass through.

[0063] It also includes a luminous intensity testing device, which is a fiber optic spectrometer 3. The fiber optic spectrometer 3 is connected to a signal display 4 and can display the collected luminous intensity information on the signal display 4.

[0064] The fiber optic spectrometer 3 and the signal display 4 can be based on existing equipment and will not be described in detail here.

[0065] Example 3

[0066] This embodiment provides a method for adjusting a battery cell clamp, including the following steps:

[0067] During the battery cycle, the expansion force distribution of the battery cell is detected using the method described in Example 1.

[0068] If the difference in luminous intensity between any two regions divided by the clamping plate is not greater than the set value, the original torque force is applied to the actual clamp to fix the battery. If there are two regions where the difference in luminous intensity is greater than the set value, the locking component between the two clamping plates is adjusted until the difference in luminous intensity between any two regions obtained by the battery expansion force distribution detection method described in Example 1 is not greater than the set value. The new torque applied to the locking component is recorded, and the new torque force is applied to the actual clamp to fix the battery.

[0069] Furthermore, the set value is 50, and it is understood that those skilled in the art can set the size of the set value according to actual needs.

[0070] In this embodiment, the distribution of cell expansion force is detected every 200 cycles. Uneven stress on the cells can be detected in time and the clamps can be adjusted, which can extend the cycle life of the battery.

[0071] Furthermore, in this embodiment, different forces can be applied to the clamp in advance, and the corresponding luminous intensity can be obtained by testing under different forces, thereby obtaining a relationship model between force and luminous intensity. When performing expansion force distribution detection, the magnitude of the expansion force on each area of ​​the clamp can be obtained based on the luminous intensity. When the expansion force is too large, the clamp needs to be adjusted as soon as possible to release the internal stress of the battery in time and avoid uneven stress leading to loss of internal battery capacity.

[0072] In a verification experiment of Examples 1, 2, and 3, the following comparative experiments were set up: Group A cell cycle test used a common fixture, and Group B cell cycle test used the fixture provided in Example 2. The difference was that the mechanoluminescent material used was SrAl2O4:Eu. 2+ All other test conditions remained the same. The experimental steps for Group B were as follows: First, a mold was designed based on the size of the battery cell to be tested, and the mechanoluminescent material SrAl2O4:Eu was placed inside. 2+ The mixture was thoroughly mixed with epoxy resin and cured to obtain the splice. Different forces were applied to the splice while simultaneously measuring the luminescence intensity; the data are shown in Table 1.

[0073]

[0074] like Figure 3 As shown, based on the force and luminous intensity, the relationship between the two is fitted: I = 0.4094F + 836.9, where F represents the applied pressure and I represents the luminous intensity. Figure 4As shown, the large surface of the battery cell under test in group B is evenly divided into 15 areas, and the clamp is fixed to both sides of the battery cell with bolts and nuts. The battery cells in groups A and B start the cyclic test simultaneously. The clamp for group A remains unchanged from the beginning to the end of the cycle and is not adjusted. Before the cyclic test of group B begins, the luminescence intensity at the clamp corresponding to the larger plane of the battery cell is tested using a fiber optic spectrometer, and the initial pressure on the larger plane of the battery cell is calculated based on the luminescence intensity. This pressure is defined as the initial pressure, and the initial pressure at all locations should be consistent. Meanwhile, the luminous intensity at each location is tested again every 200 cycles. If the difference in luminous intensity at each location is less than 50, the cell is considered to be under uniform stress. Otherwise, the bolts and nuts of the clamping plate need to be adjusted until the difference in luminous intensity at each location is less than 50. In addition, the pressure on each part of the cell can be calculated based on the relationship between luminous intensity and pressure. As the number of cycles increases, the cell will inevitably expand, and the pressure on the clamping plate will continue to increase. When the measured pressure is greater than or equal to 1.2 times the initial pressure, the bolts and nuts need to be adjusted to release the internal stress of the battery in time and avoid uneven stress leading to loss of internal capacity of the battery. Figure 5 The cycling curves for Group A and Group B cells show that, after 1200 cycles, the capacity retention rate of Group B is significantly higher than that of Group A. This demonstrates that the expansion force testing method and device provided by this invention can effectively adjust the expansion force during battery cycling, avoiding uneven stress distribution throughout the cell core and extending cycle life.

[0075] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for detecting the distribution of battery expansion force, characterized in that, Includes the following steps: The battery cell to be tested is clamped by two pre-prepared clamps, and then the clamping component between the two clamps is used to apply clamping force to the battery cell. The clamps are made of a mixture of mechanoluminescent material and transparent epoxy resin material in a set mass ratio. The luminous intensity of multiple regions divided by the clamping part corresponding to the battery cell is tested, and the distribution of the battery cell expansion force is obtained through the luminous intensity test results. The preparation method of the clamp is as follows: mix and stir the mechanoluminescent material and transparent epoxy resin in a set mass ratio, then pour the mixture into a mold for high-temperature curing, and obtain the clamp after demolding; The curing temperature of the high-temperature curing process is 120℃-160℃, and the curing time is greater than 24 hours.

2. The method for detecting battery expansion force distribution as described in claim 1, characterized in that, The set mass ratio between the mesophilic material and the epoxy resin is 1:5 to 1:

10.

3. The method for detecting battery expansion force distribution as described in claim 1, characterized in that, Methluminescent materials use SrAl2O4:Ce 3+ Or SrAl2O4:Eu 2+ Or BaSi2O2N2: Eu 2+ Or ZnS:Cu 2+ Or CaAl2Si2O8:Eu 2+ Or tetraphenylethylene derivatives or organometallic complexes.

4. The method for detecting battery expansion force distribution as described in claim 1, characterized in that, The locking component uses bolts and nuts. The four corners of the two clamping plates are provided with through holes that match the bolt shank. After the bolt passes through the through holes of the two clamping plates, the nut is threaded on and tightened. The head of the bolt and the nut together use the clamping plates to apply clamping force to the battery cell.

5. The method for detecting battery expansion force distribution as described in claim 1, characterized in that, The luminescence intensity of multiple areas of the clamp was tested using a fiber optic spectrometer.

6. A device for detecting the distribution of battery expansion force, characterized in that, It includes multiple locking components, two clamping plates, and a light intensity testing device. The clamping plates are made of a mixture of mechanoluminescent material and epoxy resin material in a set mass ratio. The locking components can cooperate with the clamping plates to apply clamping force to the battery cell between the two clamping plates.

7. The apparatus for detecting the distribution of battery expansion force as described in claim 6, characterized in that, The locking component uses bolts and nuts. The four corners of the two clamping plates are provided with through holes that match the bolt shank. After the bolt passes through the through holes of the two clamping plates, the nut is threaded on and tightened. The head of the bolt and the nut together use the clamping plates to apply clamping force to the battery cell.

8. A method for adjusting a battery cell clamp, characterized in that, Includes the following steps: The method for detecting the expansion force distribution of a battery cell as described in any one of claims 1-5 is used to detect the expansion force distribution of the battery cell. If the difference in luminous intensity between any two regions divided by the clamping plate is not greater than the set value, the original torque force is applied to the actual clamp to fix the battery. If there are two regions where the difference in luminous intensity is greater than the set value, the locking component between the two clamping plates is adjusted until the difference in luminous intensity between any two regions obtained by the method for detecting the distribution of battery expansion force is not greater than the set value. The new torque force applied to the locking component is recorded, and the new torque force is applied to the actual clamp to fix the battery.

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