Method and device for detecting expansion force distribution of battery and cell clamp adjusting method

Abstract

The invention relates to a method and device for detecting expansion force distribution of a battery and a battery cell clamp adjusting method, and the method comprises the following steps: clamping a to-be-detected battery cell by using two clamping plates prepared in advance, and enabling the two clamping plates to apply clamping force to the battery cell by using a locking part between the two clamping plates, the clamping plate is prepared by mixing a mechanoluminescent material and a transparent epoxy resin material according to a set mass ratio; according to the detection method, the luminous intensity of the multiple areas divided by the clamping plate part corresponding to the battery cell is tested, the battery cell expansion force distribution condition is obtained through the luminous intensity test result, the detection efficiency is improved by adopting the detection method, and the detection time consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of battery detection, and in particular to a method and device for detecting battery expansion force distribution, and a battery cell clamp adjustment method. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The expansion force of lithium-ion batteries during the charge and discharge cycle has a crucial impact on their cycle performance. In order to avoid the adverse effects of gas production and pole piece expansion during the charge and discharge cycle, splints are usually applied to both sides of the battery and fixed by pressure. In order to ensure that the overall force of the battery cell is uniform, the same torque force is generally applied to the fixing bolts of the clamp. In the prior art, the expansion force of the battery cell is measured by a pressure sensor, but this method can only measure the overall expansion force of the battery cell, and cannot accurately test the expansion force of a specified position. In addition, the device structure is very complex and the cost is high.

[0004] A Chinese patent application with application publication number CN118882876A discloses a battery module expansion force measuring device and an expansion force distribution testing method. By utilizing the particularity of fluorescent materials, a fluorescent solution is evenly coated on the surface of the battery cells in the battery module. When the battery cells in the battery module expand, the film-forming fluorescent material will emit light under the action of a specific light source under the stimulation of the force. The fluorescent photos are acquired and recorded by a CCD camera system, so the surface distribution of the expansion force on the module can be obtained.

[0005] However, in the technical solution of the above patent application, if the expansion force distribution test is performed on multiple battery cells, each battery 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] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method and device for detecting the distribution of battery expansion force and a battery cell clamp adjustment method, which can greatly shorten the test time and improve the test work efficiency when testing the expansion force of multiple battery cells.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

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

[0009] Using two pre-prepared clamps to clamp the battery cell to be tested, and then using a locking component between the two clamps to make the two clamps apply a clamping force to the battery cell, wherein the clamps are prepared by mixing a mesoluminescent material and an epoxy resin material in a set mass ratio;

[0010] The luminous intensity of multiple areas divided by the clamping plate 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.

[0011] Optionally, the preparation method of the splint is: mixing a force-induced luminescent material and a transparent epoxy resin in a set mass ratio, and then introducing the mixture into a mold for high-temperature curing, and then demolding to obtain the splint.

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

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

[0014] Optionally, the mechanoluminescent 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 metal organic complexes.

[0015] Optionally, the locking components are bolts and nuts, and through holes matching the bolt rods are provided at the four corners of the two clamps. The bolts pass through the through holes of the two clamps and are threadedly connected to the nuts. The nuts are tightened, and the bolt heads and nuts jointly use the clamps to apply clamping force to the battery cells.

[0016] Optionally, a fiber optic spectrometer is used to test the luminous intensity of multiple areas of the splint.

[0017] In the second aspect, an embodiment of the present invention provides a device for detecting the distribution of battery expansion force, including multiple locking components, two clamps and light intensity testing equipment, the clamps are prepared by mixing a force-induced luminescent material and an epoxy resin material in a set mass ratio, and the locking components can cooperate with the clamps to apply a clamping force to the battery cells between the two clamps through the clamps.

[0018] Optionally, the locking components are bolts and nuts, and through holes matching the bolt rods are provided at the four corners of the two clamps. The bolts pass through the through holes of the two clamps and are threadedly connected to the nuts. The nuts are tightened, and the bolt heads and nuts jointly use the clamps to apply clamping force to the battery cells.

[0019] In a third aspect, an embodiment of the present invention provides a method for adjusting a battery cell fixture, comprising the following steps:

[0020] The expansion force distribution of the battery cell is detected by using the method for detecting the expansion force distribution of the battery described in the first aspect;

[0021] If the difference in luminous intensity between any two areas divided by the splint 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 areas with a difference in luminous intensity greater than the set value, the locking part between the two splints is adjusted until the difference in luminous intensity between any two areas obtained by the method for detecting the battery expansion force distribution described in the first aspect is not greater than the set value, and the new torque force applied to the locking part is recorded, and the new torque force is applied to the actual clamp to fix the battery.

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

[0023] 1. The method for detecting the expansion force distribution of a battery of the present invention detects the expansion force of the battery by measuring the light intensity of each area of ​​a splint containing electroluminescent material, so as to obtain the distribution of the expansion force of the battery in different areas. The splint is prefabricated and can be repeatedly used for different battery cells when testing different battery cells. Compared with the method that each battery cell test of multiple battery cells needs to be coated with fluorescent material, the time consumption of the test is greatly shortened and the detection efficiency is improved.

[0024] 2. The method for detecting the battery expansion force distribution of the present invention uses a fiber optic spectrometer to detect the light intensity, and can obtain a quantitative detection result of the light intensity, thereby accurately evaluating the uniformity of the battery expansion force distribution, facilitating the subsequent adjustment of the battery fixture, and extending the battery life.

[0025] 3. The method for detecting the expansion force distribution of the battery of the present invention uses a clamping plate to clamp the battery cell for detection through a locking component, which is consistent with the actual fixing condition of the battery and can completely simulate the fixation of the battery under actual working conditions, and has better guiding significance for the subsequent adjustment of the battery clamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] Figure 1 is a flow chart of the method of embodiment 1 of the present invention;

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

[0029] Figure 3 is a force and luminous intensity fitting curve diagram in the verification test of the present invention;

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

[0031] Figure 5 It is a graph of battery cell cycle data in the verification test of the present invention;

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

[0033] 2-1. Clamp, 2-2. Bolt, 2-3. Nut. DETAILED DESCRIPTION

[0034] Example 1

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

[0036] Step 1: Prepare a 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 core, and the size of the battery core is 52*148*110mm, so the length of the clamping plate is 160mm, the height is 120mm, and the thickness is 20mm. The locking component adopts a bolt and a nut, and the diameter of the bolt is 10mm. Accordingly, through holes for the bolt rod to pass through are provided at the four corners of the two clamping plates. The clamping plate is prepared by mixing a force-induced luminescent material and an epoxy resin material with a set mass ratio, and the preparation method thereof is as follows:

[0038] The specific preparation method of the splint is:

[0039] Step 1.1: Mix the mechanoluminescent material and transparent epoxy resin in a set mass ratio and mix them evenly.

[0040] The mass ratio of the mechanoluminescent material to the epoxy resin is 1:5-1:10. 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+ Or tetraphenylethylene derivatives or metal organic complexes. In this embodiment, the mechanoluminescent material is CaAl2Si2O8:Eu 2+

[0042] CaAl2Si2O8:Eu2+ Mix with epoxy resin in a mass ratio of 1:5 and stir for 30-60 minutes to make the force-induced luminescent material evenly dispersed in the epoxy resin.

[0043] Step 1.2: The liquid obtained in step 1.1 is introduced into the mold and cured at high temperature in an oven to form a fixture of a specific shape.

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

[0045] Step 1.3: After curing is completed, demoulding is performed to obtain a splint, and then according to the diameter of the bolt, drilling is performed at the four corners of the splint by mechanical processing to obtain through holes for passing the bolts.

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

[0047] Step 3: Divide the splint part corresponding to the battery cell into multiple areas, use a fiber optic spectrometer to further test the light intensity of each area, aim the signal receiver of the fiber optic spectrometer at the corresponding area, receive the light signal of the corresponding area and test the luminous intensity, and keep records, so as to obtain the distribution of the battery cell expansion force for evaluation.

[0048] In this embodiment, when the difference in luminous intensity between any two regions tested is not greater than a set value, it is considered that the expansion force of the battery cell is evenly distributed.

[0049] Furthermore, the set value is 50. It is understandable that those skilled in the art can set the set value according to actual needs.

[0050] After the test is completed, the bolts and nuts are removed, and the clamp is restored to its original state after the extrusion force is removed, and the next battery cell expansion force distribution test can be carried out.

[0051] By adopting the detection method of this embodiment, the expansion force of the battery is detected by measuring the light intensity of each area of ​​a splint containing electroluminescent material, so that the distribution of the battery expansion force in different areas can be obtained. The splint is prefabricated and can be reused for different battery cells when detecting different battery cells. Compared with multiple battery cells, each battery cell test needs to be coated with fluorescent material, which greatly shortens the detection time and improves the detection efficiency. The battery cell is clamped by bolts and nuts using the splint for detection, which is consistent with the actual fixing condition of the battery and can completely simulate the fixation of the battery under actual working conditions, which has better guiding significance 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 luminous intensity, and a quantitative detection result of the light intensity can be obtained, so that an accurate assessment of the uniformity of the distribution of the battery expansion force can be achieved, which is convenient for subsequent adjustment of the battery fixture, ensuring that the battery cell is uniformly stressed at all locations in the initial state of the cycle, avoiding the problem of rapid failure of the cycle due to uneven force, and extending the service life of the battery.

[0053] Example 2

[0054] This embodiment provides a device for detecting the expansion force distribution of a battery, such as Figure 2 As shown, it includes a clamp 2 and a luminous intensity detection device, the clamp 2 is used to apply a 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 clamps 21 and four groups of locking components. The clamp 21 is a rectangular plate 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. Accordingly, the four corners of the clamp 21 are provided with through holes matching the spiral.

[0055] The clamping plate 221 is prepared by mixing a mechanoluminescent material and an epoxy resin material in a set mass ratio, and the preparation method thereof is as follows:

[0056] Step 1.1: Mix the mechanoluminescent material and epoxy resin in a set mass ratio and mix them evenly.

[0057] The mass ratio of the mechanoluminescent material to the epoxy resin is 1:5-1:10. 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+ Or tetraphenylethylene derivatives or metal organic complexes. Existing mesoluminescent materials can be used. In this embodiment, the mesoluminescent material is CaAl2Si2O8:Eu 2+ .

[0059] CaAl2Si2O8:Eu 2+ Mix with epoxy resin in a mass ratio of 1:5 and stir for 30-60 minutes to make the force-induced luminescent material evenly dispersed in the epoxy resin.

[0060] Step 1.2: The liquid obtained in step 1.1 is introduced into a mold and cured at high temperature in an oven.

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

[0062] Step 1.3: After curing is completed, demoulding is performed to obtain the splint 21 , and then according to the diameter of the bolt 22 , drilling is performed at the four corners of the splint 21 by a machining method to obtain through holes for passing the bolt 22 .

[0063] It also includes a luminous intensity testing device, which uses 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 may be existing devices, and will not be described in detail here.

[0065] Example 3

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

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

[0068] If the difference in luminous intensity between any two areas divided by the splint 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 areas with a difference in luminous intensity greater than the set value, the locking part between the two splints is adjusted until the difference in luminous intensity between any two areas obtained by the method for detecting the battery expansion force distribution described in Example 1 is not greater than the set value, and the new torque applied to the locking part is recorded, and the new torque force is applied to the actual clamp to fix the battery.

[0069] Furthermore, the set value is 50. It is understandable that those skilled in the art can set the set value according to actual needs.

[0070] In this embodiment, the expansion force distribution of the battery cell is detected every 200 cycles, and uneven force on the battery cell is discovered in time and the clamp is adjusted, which can extend the cycle life of the battery.

[0071] Furthermore, in this embodiment, different forces can be applied to the splint in advance, and the corresponding luminous intensities can be tested under different forces to obtain a relationship model between force and luminous intensity. When the expansion force distribution test is performed, the expansion force applied to each area of ​​the splint can be obtained according to 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 to avoid loss of internal battery capacity due to uneven stress.

[0072] In a verification test of the present embodiment 1, embodiment 2 and embodiment 3, a comparative experiment is set up as follows: the A group battery cell cycle test adopts a common fixture, and the B group battery cell cycle test adopts the fixture provided in embodiment 2. The difference is that the mechanoluminescent material adopts SrAl2O4:Eu 2+ The other test conditions remain the same. The experimental steps of group B are as follows: first, the mold is designed according to the size of the battery cell to be tested, and the mechanoluminescent material SrAl2O4:Eu 2+ Mix evenly with epoxy resin and cure to obtain a splint. Apply different forces to the splint and measure the luminous intensity at the same time. The data are shown in Table 1.

[0073] Table 1 Pressure and luminous intensity

[0074] Serial number Pressure / Pa Luminous intensity 1 100 950 2 2000 1500 3 4000 2600 4 8000 4000 5 10000 5000

[0075] like Figure 3 As shown in FIG. 1 , according to the force value and the 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 to be tested in group B is evenly divided into 15 areas, and the fixture is fixed on both sides of the battery cell by bolts and nuts. The battery cells in groups A and B start the cycle test at the same time. The fixture of the battery cell in group A remains unchanged from the beginning to the end of the cycle without adjustment. Before the battery cell in group B starts the cycle test, the luminous intensity at the corresponding clamping plate at the larger flat surface of the battery cell is tested by the optical fiber spectrometer, and the pressure of the larger flat surface of the battery cell in the initial state is calculated based on the luminous intensity. This pressure is defined as the initial pressure, and the initial pressure at each location should be kept consistent. At the same time, the luminous intensity of each location is tested again every 200 cycles. If the difference in luminous intensity at each location is less than 50, it is considered that the battery cell is evenly stressed. Otherwise, the bolts and nuts of the splint need to be adjusted until the difference in luminous intensity at each location is less than 50. In addition, the pressure at each location on the large surface of the battery cell can be calculated based on the functional relationship between luminous intensity and pressure. As the number of cycles increases, the battery cell will inevitably expand, and the pressure on the splint 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 to avoid loss of internal battery capacity due to uneven stress. Figure 5 The figure shows the cycle curves of group A and group B battery cells. When the cycle reaches 1200 cycles, it can be clearly seen that the capacity retention rate of group B is higher than that of group A. This shows that the expansion force testing method and device provided by the present invention can effectively adjust the expansion force in the battery cycle process in a timely manner to avoid uneven force on the internal winding core of the battery cell, thereby extending the cycle life.

[0076] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for detecting battery expansion force distribution, characterized in that: The following steps are involved: Using two pre-prepared clamps to clamp the battery cell to be tested, and then using a locking component between the two clamps to make the two clamps apply a clamping force to the battery cell, wherein the clamps are prepared by mixing a mesoluminescent material and a transparent epoxy resin material in a set mass ratio; The luminous intensity of multiple areas divided by the clamping plate 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.

2. The method for detecting battery expansion force distribution according to claim 1, characterized in that: The preparation method of the splint is as follows: a mechanoluminescent material and a transparent epoxy resin in a set mass ratio are mixed and stirred, and then introduced into a mold for high-temperature curing, and the splint is obtained after demoulding.

3. The method for detecting battery expansion force distribution according to claim 2, characterized in that: The curing temperature of the high temperature curing is 120° C.-160° C., and the curing time is greater than 24 hours.

4. The method for detecting battery expansion force distribution according to claim 1, characterized in that: The set mass ratio between the mesoluminescent material and the epoxy resin is 1:5-1:

10.

5. The method for detecting battery expansion force distribution according to claim 1, characterized in that: The mechanoluminescent 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 metal organic complexes.

6. The method for detecting battery expansion force distribution according to claim 1, characterized in that: The locking components are bolts and nuts. Through holes matching the bolt rods are provided at the four corners of the two clamps. The bolts pass through the through holes of the two clamps and are threadedly connected to the nuts. The nuts are tightened, and the bolt heads and nuts jointly use the clamps to apply clamping force to the battery cells.

7. The method for detecting battery expansion force distribution according to claim 1, characterized in that: A fiber optic spectrometer was used to test the luminous intensity of multiple areas of the splint.

8. A device for detecting battery expansion force distribution, characterized in that: It includes multiple locking components, two clamps and light intensity testing equipment. The clamps are made by mixing a force-induced luminescent material and an epoxy resin material in a set mass ratio. The locking components can cooperate with the clamps to apply a clamping force to the battery cell between the two clamps through the clamps.

9. The device for detecting battery expansion force distribution according to claim 8, characterized in that: The locking components are bolts and nuts. Through holes matching the bolt rods are provided at the four corners of the two clamps. The bolts pass through the through holes of the two clamps and are threadedly connected to the nuts. The nuts are tightened, and the bolt heads and nuts jointly use the clamps to apply clamping force to the battery cells.

10. A method for adjusting a battery cell fixture, characterized in that: The following steps are involved: The expansion force distribution of the battery cell is detected by using the method for detecting the expansion force distribution of the battery as described in any one of claims 1 to 7; If the difference in luminous intensity between any two areas divided by the splint 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 areas with a difference in luminous intensity greater than the set value, the locking part between the two splints is adjusted until the difference in luminous intensity between any two areas obtained by the method for detecting the battery expansion force distribution is not greater than the set value, and the new torque force applied to the locking part is recorded, and the new torque force is applied to the actual clamp to fix the battery.

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