A method and device for detecting diaphragm powder loss

Abstract

The present invention discloses a method for detecting diaphragm powder loss. The method comprises the following steps: laying a coated diaphragm flat and fixed on a loading platform; irradiating a coated side of the coated diaphragm with a laser with a light intensity of I0 through a laser transmitter; and receiving a laser with a light intensity of I1 that passes through the other side of the coated diaphragm through a laser receiver; blowing an airflow through a blowing device to impact the coating and remove powder attached to the diaphragm; irradiating the coating after the airflow impact with a laser with a light intensity of I0; and receiving a laser with a light intensity of I2 that passes through the other side of the powder loss diaphragm through a laser receiver; irradiating a side of an uncoated diaphragm with a laser with a light intensity of I0; and receiving a laser with a light intensity of I3 that passes through the other side of the uncoated diaphragm through a laser receiver; and calculating a powder loss rate of the diaphragm through the formula (I2-I1) / (I3-I1)*100%. The present invention adopts a laser testing method to measure the diaphragm powder loss rate, which has small error and high precision and can be used to formulate a diaphragm powder loss detection standard. The present invention also discloses a diaphragm powder loss detection device.

Description

Technical Field

[0001] The present invention relates to the technical field of diaphragm production, and in particular to a diaphragm powder loss detection method and a detection device thereof. Background Art

[0002] In the lithium-ion battery industry, separators are a crucial component. Slurry coating plays a crucial role in producing functional separators. However, different slurry formulations exhibit significant variations in their adhesion to the separator. Poor coating quality results in powder shedding. Large particles can puncture the separator during the hot pressing phase of the battery cell, causing a direct short circuit between the positive and negative electrodes. Therefore, the quality of the separator surface coating directly impacts the production quality of lithium-ion battery cells.

[0003] At present, the diaphragm industry has not clearly established a standard for diaphragm powder loss detection. The conventional detection method is to use fingers to wipe the diaphragm surface with a certain pressure, and judge the degree of diaphragm powder loss based on the color depth of the powder sticking on the fingers. This has the following problems: 1. Different people use different forces, and the judgment results are different; 2. The roughness of different people's fingers is different, and the possibility of touching white powder is different, and the judgment results are different; 3. The degree of powder loss is judged by the depth of color, which has a large subjective human error; the diaphragm powder loss detection disclosed in the prior art adopts a weighing method, which characterizes the degree of diaphragm powder loss by weighing the mass difference before and after the friction between the diaphragm and the friction block; however, the fluctuation deviation of this mass difference is large, and there is a large measurement error. Summary of the Invention

[0004] In response to the deficiencies in the prior art, the present invention provides a diaphragm powder loss detection method and a detection device thereof, which adopts a laser testing method to measure the diaphragm powder loss rate. The method measures the light transmittance of coated diaphragms, powder loss diaphragms and uncoated diaphragms, and calculates the powder loss rate using the light transmittance. The test error is small and the accuracy is high, and the method can be used to formulate standards for diaphragm powder loss detection.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for detecting diaphragm powder loss comprises the following steps:

[0007] Step 1: Measure the light transmittance of the coated membrane. The coated membrane is laid flat and fixed on a loading platform. A laser transmitter connected to a laser tester is used to irradiate the coated side of the membrane with a laser of light intensity I0. After the laser is absorbed by the coated membrane, a laser receiver connected to the laser tester receives the laser with light intensity I1 on the other side of the membrane.

[0008] Step 2: Measure the light transmittance of the powder-shedding membrane. Use an air blower to blow air onto the coating and remove the powder attached to the membrane. Use a laser transmitter to irradiate the coating with a light intensity of I0. After the laser is absorbed by the powder-shedding membrane, the laser is received by a laser receiver with a light intensity of I2 on the other side of the powder-shedding membrane.

[0009] Step 3: Measure the light transmittance of the uncoated diaphragm. The uncoated diaphragm is laid flat and fixed on a loading platform. A laser transmitter connected to a laser tester is used to irradiate one side of the uncoated diaphragm with a laser light intensity of I0. After the laser light is absorbed by the uncoated diaphragm, a laser receiver connected to the laser tester receives the laser light with a light intensity of I3 on the other side of the uncoated diaphragm.

[0010] Step 4: Calculate the powder loss rate of the diaphragm using the formula (I2-I1) / (I3-I1)*100%. Use the laser testing method to measure the powder loss rate of the diaphragm. This method first measures the light transmittance of the coated diaphragm, then tests the light transmittance of the powdered diaphragm after blowing the coated diaphragm, and then measures the light transmittance of the uncoated diaphragm. Finally, the powder loss rate is calculated. The test error is small and the accuracy is high, which can be used to formulate standards for diaphragm powder loss detection.

[0011] As a preferred solution, in step 1 and step 2, the position of the coating membrane on the loading platform remains unchanged before and after the blowing device blows air, and the test point position of the coating irradiated by the laser emitter is the same.

[0012] As a preferred solution, in step one and step three, before testing, a marking line is set on the side of the diaphragm to be tested facing the laser emitter, and the marking line includes a horizontal marking line and a vertical marking line, and the intersection of the horizontal marking line and the vertical marking line is the test point.

[0013] As a preferred solution, in step 1, step 2 and step 3, multiple test points are used to measure the average light transmittance of the diaphragm.

[0014] As a preferred solution, the laser emitted by the laser emitter is a short-wave laser.

[0015] As a preferred solution, in step 1, a diaphragm placement position is provided on the object-carrying platform, and the diaphragm placement position is provided with a positioning structure for fixing the diaphragm to be tested laid flat on the diaphragm placement position.

[0016] As a preferred solution, the positioning structure is a plurality of suction cups distributed at the diaphragm placement position, and the openings of the suction cups face upward.

[0017] As a preferred solution, in step 2, the angle between the blowing direction of the air nozzle on the blowing device and the diaphragm is 30° to 60°, and the distance between the air nozzle and the diaphragm is 2 cm to 20 cm.

[0018] A diaphragm powder drop detection device includes a loading platform and a laser tester. A diaphragm placement position is provided on the loading platform. The laser tester is connected to a laser emitter and a laser receiver corresponding to the laser emitter. The laser receiver is provided at the diaphragm placement position. A blowing device for blowing air to the diaphragm placed on the laser receiver is provided above the diaphragm placement position.

[0019] As a preferred solution, it further includes a laser emitter mounting plate, on one side of which multiple laser emitters are distributed, and all of the multiple laser emitters are connected to the laser tester.

[0020] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, a laser testing method is used to measure the powder loss rate of the diaphragm. The method first measures the light transmittance of the coated diaphragm, then tests the light transmittance of the powder loss diaphragm after blowing the coated diaphragm, then measures the light transmittance of the uncoated diaphragm, and finally uses the light transmittance to calculate the powder loss rate. The test error is small and the accuracy is high, and it can be used to formulate standards for diaphragm powder loss detection; the air flow is directly hit by the diaphragm coating in the form of blowing with a nozzle to replace the friction action of the traditional friction block, which can effectively avoid the influence of the friction block material, wear degree, etc. on the friction effect; the diaphragm is kept in a taut state by setting a positioning structure, so that the test data is more valid; the short-wave laser has good stability and strong anti-interference ability, which can improve the test quality.

[0021] In order to more clearly illustrate the structural features, technical means and specific objectives and functions achieved by the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the method steps of an embodiment of the present invention;

[0023] Figure 2 1 is a schematic structural diagram of a detection device according to an embodiment of the present invention;

[0024] Figure 3 1 is a schematic structural diagram of a laser tester according to an embodiment of the present invention;

[0025] Figure 4 is a top view schematically showing a diaphragm to be tested placed on a stage according to an embodiment of the present invention;

[0026] Figure 5 1. It is a schematic diagram of the assembly of the nozzle, mounting slide, lifting seat and connecting shaft according to an embodiment of the present invention;

[0027] Figure 6 It is a schematic diagram of the air blowing of the air nozzle according to an embodiment of the present invention.

[0028] Description of the accompanying drawings:

[0029] 10-carrying platform; 11-diaphragm placement position; 12-suction cup;

[0030] 13-blowing device; 14-nozzle mounting bracket; 15-nozzle;

[0031] 16-guide rail; 17-connecting shaft; 18-mounting slide;

[0032] 19-Adjusting screw; 20-Lifting seat; 30-Laser tester;

[0033] 31-laser receiver; 32-laser transmitter mounting plate; 33-laser transmitter;

[0034] 40-diaphragm; 41-test point; 42-horizontal marking line. DETAILED DESCRIPTION

[0035] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the position or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0036] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0037] like Figure 1-6 As shown, the present invention discloses a method for detecting diaphragm powder loss, comprising the following steps:

[0038] Step 1: Measure the light transmittance of the coated membrane 40. The coated membrane 40 is laid flat and fixed on the loading platform 10. A laser emitter 33 connected to a laser tester 30 irradiates the coated side of the coated membrane 40 with a laser beam having a light intensity of I0. After the laser beam is absorbed by the coated membrane 40, the laser beam having a light intensity of I1 is received by a laser receiver 31 connected to the laser tester 30.

[0039] Step 2: Measure the light transmittance of the powder removal membrane 40. The air blower 13 blows air to hit the coating and remove the powder attached to the membrane 40. The laser emitter 33 irradiates the coating after the air flow hits the coating. After the laser is absorbed by the powder removal membrane 40, the laser is received by the laser receiver 31 with a light intensity of I2 on the other side of the powder removal membrane 40.

[0040] Step 3: Measure the light transmittance of the uncoated diaphragm 40. The uncoated diaphragm 40 is laid flat and fixed on the loading platform 10. A laser emitter 33 connected to a laser tester 30 irradiates one side of the uncoated diaphragm 40 with a laser beam having a light intensity of I0. After the laser beam is absorbed by the uncoated diaphragm 40, a laser beam having a light intensity of I3 is received by a laser receiver 31 connected to the laser tester 30.

[0041] Step 4: Calculate the powder rate of the diaphragm 40 by using the formula (I2-I1) / (I3-I1)*100%.

[0042] In step 1 and step 2, the position of the coating membrane 40 on the loading platform 10 remains unchanged before and after the blowing device 13 blows air, and the test point 41 of the coating irradiated by the laser emitter 33 is the same.

[0043] In step one and step three, before testing, marking lines are set on the side of the diaphragm 40 to be tested facing the laser emitter 33. The marking lines include multiple transverse marking lines 42 and multiple longitudinal marking lines. The intersection of the transverse marking lines 42 and the longitudinal marking lines is the test point 41, and the distance between two adjacent test points 41 is 0.5 cm to 2.5 cm.

[0044] In step 1, step 2, and step 3, a plurality of test points 41 are used to measure the average light transmittance of the diaphragm 40 .

[0045] The laser emitted by the laser emitter 33 is a short-wave laser, which is an X-ray laser.

[0046] In step one, a diaphragm placement position 11 is provided on the loading platform 10, and the diaphragm placement position 11 is provided with a positioning structure for fixing the diaphragm 40 to be tested laid flat on the diaphragm placement position 11. The positioning structure is a plurality of suction cups 12 distributed on the diaphragm placement position 11, and the openings of the suction cups 12 face upward.

[0047] In step 2, the angle θ between the blowing direction of the nozzle 15 on the blowing device 13 and the diaphragm 40 is 30° to 60°, the distance h between the nozzle 15 and the diaphragm 40 is 2cm to 20cm, and the air supply volume of the nozzle 15 is 0.025m 3 / s~0.25m 3 / s, corresponding to a wind speed of 0.5m / s to 50m / s, and a moving speed of the air nozzle 15 of 0.01m / s to 0.5m / s.

[0048] like Figure 2-6 As shown, the present invention also discloses a diaphragm 40 powder loss detection device, including a loading platform 10 and a laser tester 30, wherein a diaphragm placement position 11 is provided on the loading platform 10, and the laser tester 30 is connected to a laser emitter 33 and a laser receiver 31 corresponding to the laser emitter 33, and the laser receiver 31 is provided at the diaphragm placement position 11, and a blowing device 13 for blowing air to the diaphragm 40 placed on the laser receiver 31 is provided above the diaphragm placement position 11. During the test, the diaphragm 40 to be tested is laid flat on the diaphragm placement position 11 and the diaphragm 40 is placed between the laser emitter 33 and the laser receiver 31. The laser emitted by the laser emitter 33 passes through the diaphragm 40 and is received by the laser receiver 31.

[0049] It also includes a laser emitter mounting plate 32, and a plurality of laser emitters 33 are distributed on one side of the laser emitter mounting plate 32. The plurality of laser emitters 33 are all connected to the laser tester 30. The plurality of laser emitters 33 are distributed in a matrix on the laser emitter mounting plate 32, and each laser emitter 33 corresponds one-to-one to a test point 41. By setting up a plurality of laser emitters 33 and adopting a matrix distribution arrangement, the transmittance of multiple diaphragms 40 can be measured at one time during the test, and the average transmittance can be quickly calculated, which makes the test convenient and efficient.

[0050] The blowing device 13 includes a nozzle mounting frame 14 provided on the loading platform 10, and a nozzle 15 and a nozzle 15 driving assembly (not shown) for driving the nozzle 15 to move back and forth are movably provided on the nozzle mounting frame 14. The nozzle 15 is connected to an air supply unit (not shown), and the blowing direction of the nozzle 15 is horizontally and perpendicularly to the movement direction of the nozzle 15.

[0051] A mounting slide 18 is movably provided on the nozzle mounting frame 14. The nozzle 15 driving assembly includes a screw (not shown) and a motor (not shown) for controlling the rotation of the screw. The screw extends in the front-to-back direction and is rotatably connected to the mounting slide 18. The nozzle 15 is provided on the mounting slide 18 and can move in the front-to-back direction with the mounting slide 18. By arranging the screw and the motor, the nozzle 15 can automatically blow air on the coating with good uniformity, thereby improving the accuracy of the test data.

[0052] The left and right sides of the mounting slide 18 are provided with a lifting seat 20 and an adjusting screw 19. The lifting seat 20 is movably connected to the mounting slide 18 up and down, and the adjusting screw 19 extends vertically and is screwed into the lifting seat 20. The two ends of the air nozzle 15 are rotatably connected to the corresponding lifting seat 20 through a connecting shaft 17. The connecting shaft 17 allows the air nozzle 15 to stay at any position. When adjusting, the air nozzle 15 can be manually rotated to rotate around the connecting shaft 17 to adjust the angle of the air nozzle 15. Rotating the adjusting screw drives the lifting seat 20 to move up and down to adjust the height of the air nozzle 15, thereby achieving different blowing requirements and effects. In addition, the blowing intensity of the air nozzle 15 can be controlled by adjusting the air supply volume of the air supply unit to achieve different blowing effects.

[0053] The nozzle mounting frame 14 is provided with a guide rail 16 extending in the front-to-back direction, and the mounting slide 18 is slidably connected to the guide rail 16 via a slider.

[0054] The powder loss rate of the diaphragm 40 is tested according to the above steps:

[0055] A 7μm PE diaphragm 40 was used as the uncoated diaphragm 40, and a slurry A that is easy to shed powder and a slurry B that is not easy to shed powder were selected as the coating. Laser test conditions: the air supply volume during the test was 0.1m 3 / s, the distance between the nozzle 15 and the diaphragm 40 is 4 cm, the moving speed of the nozzle 15 is 0.02 m / s, and the angle between the blowing direction and the diaphragm 40 is 45 degrees. The test results are shown in Table 1:

[0056] Table 1:

[0057]

[0058] Powder loss rate qualification standard: the powder loss rate of the diaphragm 40 is less than 15% to be qualified. As can be seen from Table 1, the powder loss rate of the coated diaphragm 40 using slurry A in Scheme 1 is greater than 15%, and the powder loss rate of the coated diaphragm 40 using slurry B in Scheme 2 is less than 15%. This test method can accurately reflect that slurry A is easy to shed powder, while slurry B is not easy to shed powder. Therefore, this test method can accurately measure the powder loss rate of the diaphragm 40.

[0059] In summary, the present invention adopts a laser testing method to measure the powder loss rate of the diaphragm. The method first measures the light transmittance of the coated diaphragm, then tests the light transmittance of the powder loss diaphragm after blowing the coated diaphragm, and then measures the light transmittance of the uncoated diaphragm. Finally, the powder loss rate is calculated using the light transmittance. The test error is small and the accuracy is high, which can be used to formulate standards for diaphragm powder loss detection; the air flow is directly hit by the diaphragm coating in the form of blowing with a nozzle instead of the friction action of the traditional friction block, which can effectively avoid the influence of the friction block material, wear degree, etc. on the friction effect; the diaphragm is kept in a taut state by setting a positioning structure, so that the test data is more valid; the short-wave laser has good stability and strong anti-interference ability, which can improve the test quality.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical practice of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for detecting diaphragm powder loss, characterized in that: The following steps are involved: Step 1: Measure the light transmittance of the coated membrane. The coated membrane is laid flat and fixed on a loading platform. A laser transmitter connected to a laser tester is used to irradiate the coated side of the membrane with a laser of light intensity I0. After the laser is absorbed by the coated membrane, a laser receiver connected to the laser tester receives the laser with light intensity I1 on the other side of the membrane. Step 2: Measure the light transmittance of the powder-shedding membrane. Use an air blower to blow air onto the coating and remove the powder attached to the membrane. Use a laser transmitter to irradiate the coating with a light intensity of I0. After the laser is absorbed by the powder-shedding membrane, the laser is received by a laser receiver with a light intensity of I2 on the other side of the powder-shedding membrane. Step 3: Measure the light transmittance of the uncoated diaphragm. The uncoated diaphragm is laid flat and fixed on a loading platform. A laser transmitter connected to a laser tester is used to irradiate one side of the uncoated diaphragm with a laser light intensity of I0. After the laser light is absorbed by the uncoated diaphragm, a laser receiver connected to the laser tester receives the laser light with a light intensity of I3 on the other side of the uncoated diaphragm. Step 4: Calculate the powder loss rate of the diaphragm by using the formula (I2-I1) / (I3-I1)*100%.

2. A method for detecting diaphragm powder loss according to claim 1, characterized in that: In step 1 and step 2, the position of the coating membrane on the loading platform remains unchanged before and after the blowing device blows air, and the test point position of the coating irradiated by the laser emitter is the same.

3. A method for detecting diaphragm powder loss according to claim 1 or 2, characterized in that: In step 1 and step 3, before testing, marking lines are set on the side of the diaphragm to be tested facing the laser emitter. The marking lines include a horizontal marking line and a vertical marking line, and the intersection of the horizontal marking line and the vertical marking line is the test point.

4. A method for detecting diaphragm powder loss according to claim 1, characterized in that: In steps 1, 2, and 3, the average light transmittance of the diaphragm is measured using multiple test points.

5. A method for detecting diaphragm powder loss according to claim 1, characterized in that: The laser emitted by the laser emitter is a short-wave laser.

6. A method for detecting diaphragm powder loss according to claim 1, characterized in that: In step 1, a diaphragm placement position is provided on the object-carrying platform, and the diaphragm placement position is provided with a positioning structure for fixing the diaphragm to be tested laid flat on the diaphragm placement position.

7. A method for detecting diaphragm powder loss according to claim 6, characterized in that: The positioning structure is a plurality of suction cups distributed at the diaphragm placement position, and the openings of the suction cups face upward.

8. A method for detecting diaphragm powder loss according to claim 1, characterized in that: In step 2, the angle between the blowing direction of the air nozzle on the blowing device and the diaphragm is 30° to 60°, and the distance between the air nozzle and the diaphragm is 2cm to 20cm. The air supply volume of the air nozzle is adjusted to remove the powder attached to the diaphragm.

9. A diaphragm powder drop detection device, characterized in that: The device comprises a loading platform and a laser tester, wherein the loading platform is provided with a diaphragm placement position, the laser tester is connected to a laser emitter and a laser receiver corresponding to the laser emitter, the laser receiver is provided at the diaphragm placement position, and a blowing device for blowing air to the diaphragm placed on the laser receiver is provided above the diaphragm placement position; The diaphragm placement position is provided with a positioning structure for fixing the diaphragm to be tested laid flat on the diaphragm placement position, and the blowing device includes a nozzle mounting frame arranged on the loading platform, and the nozzle mounting frame is movably provided with a nozzle and a nozzle driving assembly for driving the nozzle to move back and forth, the nozzle is connected to an air supply unit, and the blowing direction of the nozzle is horizontally perpendicular to the movement direction of the nozzle.

10. The diaphragm powder loss detection device according to claim 9, characterized in that: It also includes a laser emitter mounting plate, on one side of which a plurality of laser emitters are distributed, and the plurality of laser emitters are all connected to the laser tester.

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