Lithium battery diaphragm wettability testing device and testing method thereof

Abstract

The invention discloses a lithium battery diaphragm wettability testing device and a testing method thereof.The lithium battery diaphragm wettability testing device comprises a device body provided with a base and a detachable shell, an electrolyte tank is arranged above the base, and a vertical diaphragm clamping support used for fixing a diaphragm to be tested is placed in the electrolyte tank; two ends of the electrolyte tank are respectively provided with a measuring scale and a lifting rod, and the top of the lifting rod is provided with an infrared laser positioner used for assisting in measuring the climbing height of the electrolyte in the diaphragm to be measured. The climbing reading deviation of the diaphragm to be detected is reduced, and the wettability detection precision is improved.

Description

Technical Field

[0001] This application relates to the technical field of lithium batteries, and particularly to a testing device and method for the wetting performance of a lithium battery separator. Background Art

[0002] The wetting performance of a lithium battery separator is one of the key factors affecting battery performance and safety. By optimizing the electrolyte distribution and ion transport efficiency, it indirectly improves the battery's cycle life and reduces the wetting time and internal resistance during the liquid injection process. Placing the separator vertically, fixing one end, and contacting the other end with the electrolyte, and measuring the climbing height of the electrolyte after a certain period of time is an intuitive test method for measuring the climbing performance of the electrolyte. And compared with the horizontal diffusion test, this method is closer to the penetration process of the electrolyte under the action of gravity during the liquid injection of a cylindrical battery. It can be used to simply evaluate the pros and cons of the wetting performance of the separator in the longitudinal direction.

[0003] In traditional tests, the setting of fixing the upper end of the separator with a fixture and immersing the lower end in the electrolyte may cause baseline errors due to deviations in the immersion depth or uneven fixture pressure. In addition, manual visual inspection of the climbing height and the uncontrolled temperature and humidity environment (affecting the viscosity and volatilization of the electrolyte) easily result in poor data repeatability. It is necessary to reduce experimental errors by controlling temperature and humidity, improving the film clamping device, and stabilizing the measurement method. Summary of the Invention

[0004] The purpose of the present invention is to provide a testing device and method for the wetting performance of a lithium battery separator, which solves the problem that the final wetting performance accuracy is poor due to manual visual inspection of the climbing height of the electrolyte in the separator to be tested, reduces the climbing reading deviation of the separator to be tested, and improves the detection accuracy of the wetting performance.

[0005] To solve the above technical problems, the present invention adopts the following solutions:

[0006] A testing device for the wetting performance of a lithium battery separator, characterized in that it includes a device body with a base and a detachable outer shell. Above the base is provided an electrolyte pool. Inside the electrolyte pool is placed a vertical film clamping bracket for fixing the separator to be tested. At both ends of the electrolyte pool are respectively provided a measuring scale and a lifting rod. At the top of the lifting rod is provided an infrared laser locator for assisting in measuring the climbing height of the electrolyte in the separator to be tested.

[0007] Further, the vertical film clamping bracket includes a top plate, a bottom plate, and a connecting rod located between the top plate and the bottom plate. The top plate and the bottom plate are respectively provided with a corresponding long slot and a groove. The separator to be tested is cut and then sequentially passes through the two long slots and is fixed in the groove.

[0008] Further, it also includes a magnetic block for limiting. The magnetic block is located in the groove and on the surface of the separator to be tested.

[0009] Further, the top plate and the bottom plate are respectively made of metal materials.

[0010] Further, the number of the grooves is at least three.

[0011] Further, the electrolyte cell includes a liquid holding cell and fixing plates located on both sides of the liquid holding cell, and the zero scale line of the measuring ruler is flush with the fixing plates.

[0012] Further, the lifting rod drives the infrared laser locator to rise to the climbing height.

[0013] Further, it further includes a switch located at the end of the base, and the switch is electrically connected to the lifting rod.

[0014] Further, an installation groove for assembling with the bottom end of the outer shell is provided on the surface of the base, the front and two side surfaces of the outer shell are transparent plastic plates, and the back surface of the outer shell is a black plastic plate.

[0015] A method for testing the wetting performance of a lithium battery separator, using the above-mentioned device for testing the wetting performance of a lithium battery separator, includes the following steps:

[0016] S1, fixing the separator to be tested: After the separator to be tested is cut into regular strips, both ends of the separator to be tested are respectively passed through the long grooves of the top plate and the bottom plate in the vertical film clamping bracket and are parallel to the grooves; then both ends of the separator to be tested are respectively vertically bent into the grooves of the top plate or the bottom plate, and magnetic blocks are placed in the grooves for fixing;

[0017] S2, placing the vertical film clamping bracket loaded with the separator to be tested: Place the vertical film clamping bracket in the liquid holding cell, after the infrared laser locator, the measuring ruler and the separator to be tested are on the same horizontal line, inject the electrolyte;

[0018] S3, wetting performance test: Calculate the liquid absorption rate of the separator to be tested by the wetting climbing speed of the electrolyte in the separator to be tested per unit time, and use the liquid absorption rate to represent the wetting performance:

[0019] Liquid absorption rate = h / t;

[0020] Wherein, h represents the wetting climbing height of the electrolyte in the separator, and t represents the time.

[0021] The beneficial effects of the present invention are:

[0022] In the present invention, the separator to be tested is fixed by using magnets and grooves in the top plate and the bottom plate of the vertical film clamping bracket, which enhances the stability of the separator to be tested during the test process, prevents the separator to be tested from shifting, and improves the accuracy of the climbing height and wetting performance measured in the vertical direction of the separator to be tested.

[0023] The infrared rays generated by the infrared laser locator are used to synchronously mark the climbing height in the diaphragm to be measured and the measuring scale, enabling the climbing height of the electrolyte to be measured and read more conveniently and accurately, and avoiding the errors caused by visual measurement.

[0024] The back of the housing uses black as the background, enabling the climbing height of the electrolyte to be observed more clearly and reducing errors. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of the present invention;

[0026] Figure 2 It is a schematic structural diagram of the vertical film clamping rack of the present invention;

[0027] Figure 3 It is a top view structural diagram of the vertical film clamping rack of the present invention;

[0028] Figure 4 It is a top view structural diagram of the base of the present invention;

[0029] Figure 5 It is a physical diagram of the climbing height of the electrolyte when the diaphragm to be measured is tested for 30 minutes;

[0030] Figure 6 It is a trend diagram of the climbing height of the electrolyte within 15 hours when the diaphragm to be measured is tested.

[0031] Reference numerals: 1 - device body, 10 - base, 11 - housing, 12 - installation groove, 2 - electrolyte cell, 20 - liquid carrier cell, 21 - measuring scale, 22 - fixing plate, 3 - vertical film clamping bracket, 30 - top plate, 31 - bottom plate, 32 - groove, 33 - magnet, 34 - long slot, 35 - connecting rod, 4 - lifting rod, 5 - infrared laser locator, 6 - switch, 7 - diaphragm to be measured. Detailed Embodiments

[0032] 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 drawings of the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0033] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps described in these embodiments do not limit the scope of the present invention.

[0034] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0035] In addition, for the sake of clarity and conciseness, descriptions of well-known structures, functions, and configurations may be omitted. Those of ordinary skill in the art will recognize that various changes and modifications can be made to the examples described herein without departing from the spirit and scope of the present disclosure.

[0036] Technologies, methods, and devices known to those of ordinary skill in the relevant fields may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the authorization specification.

[0037] In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0038] Embodiment 1

[0039] Embodiment 1 provides a device for testing the wetting performance of a lithium battery separator, including a device body 1 provided with a base 10 and a detachable outer shell 11. An electrolyte pool 2 is arranged above the base 10. A vertical diaphragm clamping bracket 3 for fixing the separator 7 to be tested is placed inside the electrolyte pool 2. A measuring scale 21 and a lifting rod 4 are respectively arranged at both ends of the electrolyte pool 2. An infrared laser locator 5 for assisting in measuring the climbing height of the electrolyte in the separator 7 to be tested is arranged at the top of the lifting rod 4.

[0040] Referring to Figures 1 to 2 , the technical concept of this application is to arrange an electrolyte pool 2 and a vertical diaphragm clamping bracket 3 for fixing the separator 7 to be tested inside the device body 1 with a base 10 and a detachable outer shell 11. The vertical diaphragm clamping bracket 3 is erected inside the electrolyte pool 2. During the process of testing the wetting performance, the electrolyte in the electrolyte pool 2 will soak into the separator 7 to be tested for liquid absorption, resulting in the climbing of the electrolyte in the separator 7 from bottom to top. The climbing height of the electrolyte per unit time is calculated to represent the wetting performance of the separator 7 to be tested. The measurement of the climbing height is mainly through the measuring scale 21 arranged at one end of the electrolyte pool 2. By starting the lifting rod 4, the infrared laser locator 5 is raised to the climbing height of the electrolyte in the separator 7 to be tested at this time. At the same time, the infrared ray of the infrared laser locator 5 is turned on, so that this infrared ray is on the same horizontal line as the climbing height, and the infrared ray is also directly marked on the measuring scale 21 at the same time, so as to obtain the value of the climbing height at this time. After recording, the wetting performance is obtained through calculation. When reading the value of the climbing height, the numerical error caused by visual inspection is avoided, thereby improving the accuracy of the final wetting performance.

[0041] In some preferred embodiments, the vertical diaphragm holder 3 includes a top plate 30, a bottom plate 31, and a connecting rod 35 located between the top plate 30 and the bottom plate 31. The top plate 30 and the bottom plate 31 are respectively provided with a corresponding long slot 34 and a groove 32. The diaphragm 7 to be measured is successively passed through the two long slots 34 after being cut and fixed in the groove 32.

[0042] Specifically, referring to Figure 3 , the bottom plate 31, the top plate 30, and the connecting rod 35 form the overall framework of the vertical diaphragm holder 3, which are connected by welding to improve the stability during handling. At the same time, the diaphragm 7 to be measured is respectively passed through the two long slots 34, and the end portions of both ends are respectively located at the groove 32 for fixed limit. Since the top plate 30 and the bottom plate 31 are two identical plates, that is, the long slots 34 and the grooves 32 are of the same size and located on the same vertical axis, and they correspond to each other, so that the diaphragm 7 fixed by the two grooves 32 on the same vertical axis is in a vertical state, avoiding tilting when fixing the diaphragm 7 to be measured, resulting in a large deviation in the measured climbing height.

[0043] To facilitate the fixed limit of the diaphragm 7 to be measured in the groove 32, a magnetic block 33 for limit is further included. The magnetic block 33 is located in the groove 32 and on the surface of the diaphragm 7 to be measured. The top plate 30 and the bottom plate 31 are respectively made of a metal material.

[0044] It should be noted that the depth of the groove 32 is set according to actual needs. The height of the magnetic block 33 is greater than the depth of the groove 32, so that the magnetic block 33 can better play a fixing role and improve the limit firmness of the diaphragm 7 to be measured. At the same time, the top plate 30 and the bottom plate 31 made of a metal material are respectively limited by the magnetic attraction of the magnetic block 33 and are convenient for disassembly.

[0045] In some preferred embodiments, the number of the grooves 32 is at least three. In this application, the number of the grooves 32 is nine. The number of the grooves 32 provides repeated experiments for the diaphragm 7 to be measured under the same conditions during the test of the infiltration performance, so that the error of the finally obtained climbing height and infiltration performance is minimized and the test accuracy is improved.

[0046] In some preferred embodiments, the electrolyte cell 2 includes a liquid carrier cell 20 and fixing plates 22 located on both sides of the liquid carrier cell 20. The zero scale line of the measuring ruler 21 is flush with the fixing plate 22. Here, mainly the fixing plate 22 is used as a reference line during the test. During the injection of the electrolyte, the highest height of the electrolyte is the plane on the surface of the fixing plate 22, preventing the liquid level of the electrolyte from decreasing during the infiltration of the diaphragm 7 to be measured, resulting in an inaccurate reference line.

[0047] In some preferred embodiments, the lifting rod 4 drives the infrared laser locator 5 to rise to the climbing height. There is also a switch 6 located at the end of the base 10, and the switch 6 is electrically connected to the lifting rod 4. When measuring the climbing height within a certain unit time, the switch 6 and the external controller are turned on to turn on the infrared ray of the infrared laser locator 5, and the lifting rod 4 automatically performs a lifting activity, so that the infrared laser locator 5 successively marks the climbing height within the nine grooves 32 on the scale in the measuring ruler 21 through the infrared ray, and then reads the numbers in sequence. The infrared laser locator 5 provides a reference line for the readings in the measuring ruler 21, making the climbing height readings of each diaphragm 7 to be measured more accurate, thereby improving the accuracy of the final wetting performance and preventing deviations caused during reading.

[0048] Meanwhile, for the convenience of reading, an installation groove 12 for assembling with the bottom end of the outer shell 11 is arranged on the surface of the base 10. Refer to Figure 4 , the front and two side surfaces of the outer shell 11 are transparent plastic plates, and the back surface of the outer shell 11 is a black plastic plate. Using the back surface of the outer shell 11 to be black is convenient for the infrared laser locator 5 to mark on the diaphragm 7 to be measured and the measuring ruler 21, and speeds up the reading speed. The other side surfaces are transparent, which is beneficial to observing the lifting activity of the lifting rod 4. The base 10 is provided with an installation groove 12 adapted to the bottom end of the outer shell 11, improving the assembly firmness and convenient disassembly of the two, and preventing deviation during the test process.

[0049] Embodiment 2

[0050] This Embodiment 2 is a method for testing the wetting performance of a lithium battery diaphragm. Using the device for testing the wetting performance of a lithium battery diaphragm in Embodiment 1, it includes the following steps:

[0051] S1. Fix the diaphragm 7 to be measured: After the diaphragm 7 to be measured is cut into regular strips, both ends of the diaphragm 7 to be measured are respectively passed through the long slots 34 of the top plate 30 and the bottom plate 31 in the vertical film clamping bracket 3 and are parallel to the grooves 32; then both ends of the diaphragm 7 to be measured are respectively vertically bent into the grooves 32 of the top plate 30 or the bottom plate 31, and a magnetic block 33 is placed in the grooves 32 for fixation;

[0052] The angle during the bending process is 90°, and at the same time, it is bent along the side of the long slot 34 adjacent to the groove 32.

[0053] S2. Place the vertical film clamping bracket 3 loaded with the diaphragm 7 to be measured: Place the vertical film clamping bracket 3 in the liquid loading pool 20. After the infrared laser locator 5, the measuring ruler 21 and the diaphragm 7 to be measured are on the same horizontal line, inject the electrolyte;

[0054] Use the infrared rays emitted by the infrared laser locator 5 to make the forehead treasure measuring ruler 21 and the diaphragm to be measured be on the same horizontal line. Inject the electrolyte into the liquid carrier pool 20 until the height of the electrolyte reaches the surface of the fixed plate 22, and stop injecting the electrolyte when it just does not overflow. Place the bottom end of the outer shell 11 in the installation groove 12 to sleeve the vertical film clamping bracket 3 and the electrolyte pool 2. Control the infrared rays in the infrared laser locator 5 by turning on the switch 6 at the right end of the outer shell 11 to complete the measurement of the climbing height of the electrolyte. Record these climbing readings in sequence to obtain multiple h1, h2,... hn.

[0055] S3, Infiltration performance test: Calculate the liquid absorption rate of the diaphragm to be measured 7 by the infiltration climbing speed of the electrolyte in the diaphragm to be measured 7 per unit time, and use the liquid absorption rate to represent the infiltration performance:

[0056] Liquid absorption rate = h / t;

[0057] where h represents the infiltration climbing height of the electrolyte in the diaphragm, and t represents time.

[0058] Under the conditions of a test temperature of 20 °C and a humidity of 50%, fix the diaphragm to be measured 7 in the vertical film clamping bracket 3, and use the above-mentioned infiltration test device to test the infiltration performance. Test the infiltration performance of the electrolyte in the diaphragm to be measured 7 for 15 h. After the diaphragm to be measured 7 is soaked in the electrolyte for 30 min, the infiltration height rises. At this time, the climbing height of the electrolyte in 30 min is 42 mm, so the liquid absorption rate is 42 / 30 = 1.4 mm / min. Refer to Figure 5 And count the climbing heights of the diaphragm to be measured 7 at different times within 15 h, and draw a trend chart of the climbing height over a long time. Refer to Figure 6 .

[0059] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the technical solution scope of the present invention, can make some changes or modifications to the above-disclosed technical content to be equivalent embodiments with equivalent changes. However, as long as it does not depart from the technical solution content of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still belong to the scope of the technical solution of the present invention.

Claims

1. A lithium battery separator wetting performance testing device, characterized in that, It includes a device body (1) provided with a base (10) and a detachable housing (11). Above the base (10), an electrolyte bath (2) is provided. Inside the electrolyte bath (2), a vertical diaphragm clamping bracket (3) for fixing the diaphragm to be tested (7) is placed. At both ends of the electrolyte bath (2), a measuring scale (21) and a lifting rod (4) are respectively provided. At the top of the lifting rod (4), an infrared laser locator (5) for assisting in measuring the climbing height of the electrolyte in the diaphragm to be tested (7) is provided.

2. The lithium battery separator wetting performance testing device according to claim 1, characterized in that, The vertical diaphragm clamping bracket (3) includes a top plate (30), a bottom plate (31), and a connecting rod (35) located between the top plate (30) and the bottom plate (31). The top plate (30) and the bottom plate (31) are respectively provided with corresponding long slots (34) and grooves (32). After being cut, the diaphragm to be tested (7) sequentially passes through the two long slots (34) and is fixed in the grooves (32).

3. The lithium battery separator wetting performance testing device according to claim 2, wherein It further includes a magnetic block (33) for limiting, and the magnetic block (33) is located in the groove (32) and on the surface of the diaphragm to be tested (7).

4. The lithium battery separator wettability testing device according to claim 2, characterized in that, The top plate (30) and the bottom plate (31) are respectively made of metal materials.

5. A lithium battery diaphragm wetting performance testing device according to claim 2, wherein The number of the grooves (32) is at least three.

6. The lithium battery separator wetting performance testing device according to claim 2, wherein The electrolyte bath (2) includes a liquid carrier bath (20) and fixing plates (22) located on both sides of the liquid carrier bath (20). The zero scale line of the measuring scale (21) is flush with the fixing plate (22).

7. The lithium battery separator wetting performance testing device according to claim 2, wherein The lifting rod (4) drives the infrared laser locator (5) to rise to the climbing height.

8. The lithium battery separator wetting performance testing device according to claim 2, wherein, It further includes a switch (6) located at the end of the base (10), and the switch (6) is electrically connected to the lifting rod (4).

9. The lithium battery separator wettability test device according to claim 2, wherein The surface of the base (10) is provided with a mounting groove (12) for assembling with the bottom end of the housing (11). The front and two side surfaces of the housing (11) are transparent plastic plates, and the back surface of the housing (11) is a black plastic plate.

10. A method for testing the wetting performance of a lithium battery separator, characterized in that, Using a lithium battery diaphragm wetting performance testing device according to any one of claims 1 to 9, it includes the following steps: S1, fixing the diaphragm to be tested (7): After the diaphragm to be tested (7) is cut into regular strips, both ends of the diaphragm to be tested (7) respectively pass through the long slots (34) of the top plate (30) and the bottom plate (31) in the vertical diaphragm clamping bracket (3) and are parallel to the grooves (32); then both ends of the diaphragm to be tested (7) are respectively vertically bent into the grooves (32) of the top plate (30) or the bottom plate (31), and a magnetic block (33) is placed in the grooves (32) for fixing; S2, placing the vertical diaphragm clamping bracket (3) loaded with the diaphragm to be tested (7): Place the vertical diaphragm clamping bracket (3) in the liquid carrier bath (20). After the infrared laser locator (5), the measuring scale (21), and the diaphragm to be tested (7) are on the same horizontal line, inject the electrolyte; S3, wetting performance testing: Calculate the liquid absorption rate of the diaphragm to be tested (7) through the wetting climbing speed of the electrolyte in the diaphragm to be tested (7) per unit time, and use the liquid absorption rate to represent the wetting performance: Liquid absorption rate = h / t; Among them, h represents the infiltration and climbing height of the electrolyte in the separator, and t represents time.

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