Apparatus and method for evaluating heat shrinkage rate of separation membrane

Abstract

The present invention relates to an apparatus and method for evaluating the heat shrinkage rate of a separation membrane, which can easily evaluate the heat shrinkage rate of a separation membrane.

Description

[Technical field]

[0001] This invention claims the benefit of the filing date of Korean Patent Application No. 10-2022-0119715, filed with the Korean Intellectual Property Office on September 22, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an apparatus and method for evaluating the heat shrinkage rate of a separator, which is one of the basic materials for a battery, and which can easily evaluate the heat shrinkage rate of the separator. [Background technology]

[0003] Generally speaking, a separator is one of the basic materials in a battery that stores battery energy. This separator is located between the positive and negative electrodes and physically blocks the contact between the two electrodes, allowing only small lithium ions to pass through selectively, making it essential for the safe use of electrical energy.

[0004] Recently, there have been cases of fires occurring in vehicles and facilities using large-capacity batteries, making their stability even more important, and safety standards for separators are being strengthened.

[0005] The heat shrinkage evaluation item of the separation membrane, which is one of the items for evaluating the stability of the separation membrane, is a method for evaluating the degree to which the separation membrane shrinks due to heat.

[0006] Specifically, in the conventional method for measuring the thermal shrinkage rate, a separator sample is shrunk at a specific temperature for a specific time, and then an operator directly measures the degree of shrinkage using a ruler.

[0007] However, the conventional heat shrinkage evaluation method as described above is based on the concept of simply measuring the length of a separator sample, and has the disadvantages of low accuracy and reliability and a very slow evaluation speed. In particular, if the separator sample cannot maintain a rectangular shape with an internal angle of 90° after shrinkage, it is difficult to measure the shrinkage rate. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention is intended to solve the above problems, and has an object to provide an apparatus and method for evaluating the heat shrinkage rate of a separation membrane, which can easily evaluate the heat shrinkage rate of a separation membrane. [Means for solving the problem]

[0009] To achieve the above object, the apparatus for evaluating the thermal shrinkage rate of a separation membrane according to the present invention includes a mounting stage on which a separation membrane sample to be evaluated is placed, an illumination unit that irradiates light toward at least one of the top and bottom surfaces of the separation membrane sample, an imaging unit that images the separation membrane sample, and an evaluation unit that determines the degree of shrinkage of the separation membrane sample by comparing measured values ​​of lengths of the separation membrane sample in first and second directions through the image captured by the imaging unit with reference values ​​before thermal shrinkage.

[0010] In this case, the separation membrane sample may include at least four reference points forming a rectangle among a plurality of points indicating a frame boundary of the separation membrane sample.

[0011] The separation membrane sample may be formed in a quadrangular shape, and the reference point may be a vertex of the separation membrane sample.

[0012] The evaluation unit may determine the degree of shrinkage of the separation membrane sample in a first measurement range, which is set by selecting two reference points from the four reference points that are closest to a center of the separation membrane sample in the second direction, that is, a Y-axis direction, forming parallel imaginary horizontal lines passing through the two selected reference points, and measuring the length of the separation membrane sample in the first direction, that is, an X-axis direction, in a range between the imaginary horizontal lines, and a second measurement range, which is set by selecting two reference points from the four reference points that are closest to a center of the separation membrane sample in the X-axis direction, forming parallel imaginary vertical lines passing through the two selected reference points, and measuring the length of the separation membrane sample in the Y-axis direction in a range between the imaginary vertical lines.

[0013] Moreover, the evaluation section can select, as a measurement value, the shortest length among a plurality of lengths measured within the first measurement range and the second measurement range.

[0014] Also, the evaluation unit may recognize the separation membrane sample using a difference in brightness or grayscale of the captured image.

[0015] The illumination unit may further include a first illumination unit provided below the mounting table and irradiating light toward a bottom surface of the separation membrane sample, and a second illumination unit provided above the mounting table and irradiating light toward an upper surface of the separation membrane sample.

[0016] Also, the first illumination unit can be integrally inserted inside the base and can irradiate light toward the entire area of ​​the base.

[0017] The photographing unit is provided above the stand.

[0018] Meanwhile, the method for evaluating the heat shrinkage rate of a separator according to the present invention includes a first step of cutting a separator sample to be evaluated to a predetermined reference value, and setting at least four reference points on an upper surface of the cut separator sample; a second step of shrinking the separator sample by applying heat at a predetermined temperature for a predetermined time; a third step of placing the shrunken separator sample on an upper surface of a mounting table and taking an image of the separator sample; and a third step of selecting two of the four reference points that are disposed closest to the center of the plane of the separator sample in the Y-axis direction based on the taken image, and drawing a plane that passes through each of the two selected reference points. a fourth step of forming a virtual horizontal line and measuring a length of the separation membrane sample in the X-axis direction in a range between the virtual horizontal lines; a fifth step of selecting two of the four reference points that are disposed closest to a center of the separation membrane sample in the X-axis direction from a plane center of the separation membrane sample based on the captured image, forming parallel virtual vertical lines passing through the two selected reference points, and measuring a length of the separation membrane sample in the Y-axis direction in a range between the virtual vertical lines; and a sixth step of comparing the measured length measurements in the X-axis and Y-axis directions with reference values ​​to calculate a thermal shrinkage rate.

[0019] In this case, in the fourth step and the fifth step, the shortest length among the measured lengths in the X-axis and Y-axis directions can be selected as the measured value. Effect of the Invention

[0020] The apparatus and method for evaluating the heat shrinkage rate of a separator according to the present invention, preferably configured as described above, set first and second measurement ranges in the X- and Y-axis directions based on four reference points set on a rectangular separation membrane sample, measure the shortest length of the separation membrane sample within each measurement range, and compare the measured value with a reference value, thereby measuring the heat shrinkage rate, which has the advantage of being able to obtain more accurate data. [Brief description of the drawings]

[0021] [Figure 1]1 is an overall schematic diagram showing an apparatus for evaluating the heat shrinkage rate of a separation membrane according to the present invention. [Diagram 2] FIG. 2 is a schematic perspective view of an apparatus for evaluating the heat shrinkage rate of a separation membrane according to the present invention. [Diagram 3] FIG. 2 is a plan view showing a separator sample before and after heat shrinking according to the present invention. [Figure 4] FIG. 4 is a diagram showing the principle of measuring the shrinkage rate in the X-axis direction of a separation membrane sample using an evaluation unit according to the present invention. [Diagram 5] FIG. 4 is a diagram showing the principle of measuring the shrinkage rate in the X-axis direction of a separation membrane sample using an evaluation unit according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the configuration and operation of specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0023] Here, when assigning reference symbols to the components in each drawing, it should be noted that, as far as possible, identical components are represented by the same symbols even if they are shown in different drawings.

[0024] FIG. 1 is an overall schematic diagram showing an apparatus for evaluating the heat shrinkage rate of a separator according to the present invention, and FIG. 2 is a schematic perspective view of the apparatus for evaluating the heat shrinkage rate of a separator according to the present invention.

[0025] 1 and 2, a separator heat shrinkage evaluation device 100 according to a preferred embodiment of the present invention may include a mounting table 110, an illumination unit 120, an imaging unit 140, and an evaluation unit 150.

[0026] The configuration of the present invention will be specifically described as follows.

[0027] First, the mounting table 110 is formed as a plate on which the separation membrane sample 1 to be evaluated is placed. The mounting table 110 is made of a transparent or semi-transparent material so that the boundary of the separation membrane sample 1 can be easily identified by the illumination unit 120 described below. Of course, the present invention is not limited to this and can be modified and applied in various ways.

[0028] Referring to FIG. 3, the separation membrane sample 1 placed on the mounting table 110 is formed in a rectangular shape (5 cm x 5 cm), for example, so that the degree of shrinkage can be easily measured, and the separation membrane sample 1 in a heat-shrunk state is placed on the upper surface of the mounting table 110.

[0029] That is, the reference value R of the size of the separation membrane sample 1 before shrinkage may be a standardized rectangular shape, and the degree of shrinkage can be evaluated by measuring the length of the separation membrane sample 1 in a specific direction after shrinkage using the heat shrinkage evaluation device 100. A more specific shrinkage evaluation method will be described later.

[0030] Furthermore, at least four reference points P1 to P4 constituting a rectangle among a plurality of points indicating the frame boundary of the sample are set on the upper surface of the separation membrane sample 1. In this case, for the sake of convenience of explanation, the present invention illustrates and describes an example in which the reference points P1 to P4 are formed at the same positions (vertices) before and after the separation membrane sample 1 is thermally shrunk. Of course, this is not limited to this, and the reference points P1 to P4 may be displayed in the form of marks at predetermined positions formed on the upper surface of the separation membrane sample 1 in various shapes other than the vertices of a rectangle.

[0031] The illumination unit 120 can irradiate light toward at least one of the top and bottom surfaces of the separation membrane sample 1 .

[0032] For example, referring to FIG. 2, the illumination unit 120 may include a first illumination unit 121 provided under the mounting table 110 and irradiating light toward the bottom surface of the separation membrane sample 1 .

[0033] Preferably, the first lighting unit 121 is integrally inserted into the base 110 so as to irradiate light toward the entire area of ​​the base 110 .

[0034] As another example, the illumination unit 120 may include a second illumination unit 122 disposed above the mounting table 110 and irradiating light toward the upper surface of the separation membrane sample 1 .

[0035] In this case, at least one second illumination unit 122 may be provided immediately above the mounting table 110, or a pair of second illumination units 122 may be provided symmetrically on both sides of the upper portion of the mounting table 110, and may obliquely irradiate light toward the separation membrane sample 1. In this case, the present invention does not limit the specific arrangement structure of the second illumination unit 122.

[0036] The photographing unit 140 photographs the separation membrane sample 1, and as an example, the photographing unit 140 is disposed at a distance directly above the separation membrane sample 1 placed on the upper surface of the mounting table 110. The photographing unit 140 can photograph the separation membrane sample 1 irradiated with light by the first illumination unit 121 and the second illumination unit 122.

[0037] The evaluation unit 150 measures the thermal shrinkage rate of the separation membrane sample 1 through the image captured by the photographing unit 140. The evaluation unit 150 can determine the degree of shrinkage by comparing the measured values ​​L1 and L2, which are lengths of the separation membrane sample 1 in the first and second directions based on reference points P1 to P4 set on the upper surface of the separation membrane sample 1, with a reference value R (see FIG. 3) before thermal shrinkage.

[0038] In this case, the evaluation unit 150 can recognize the separation membrane sample 1 using the difference in brightness or gray scale of the captured image.

[0039] In addition, the evaluation unit 150 can set a first measurement range d1 (see FIG. 4) for measuring the length of the separation membrane sample 1 in the X-axis direction, which is a first direction, and a second measurement range d2 (see FIG. 5) for measuring the length of the separation membrane sample 1 in the Y-axis direction, which is a second direction.

[0040] 4, the first measurement range d1 may be determined by selecting two reference points P1 and P3 that are closest to the center of the plane of the separation membrane sample 1 in the Y-axis direction from among four reference points set on the upper surface of the separation membrane sample 1, and forming parallel imaginary horizontal lines h1 and h2 that pass through the two selected reference points P1 and P3. Then, the length L1 of the separation membrane sample 1 in the X-axis direction may be measured in the first measurement range d1 between the imaginary horizontal lines h1 and h2. In this case, the evaluation unit 150 may select the shortest length L1 among the multiple lengths L1 measured within the first measurement range d1 as the measured value L1.

[0041] 5, the second measurement range d2 may be determined by selecting two reference points P2 and P4 that are closest to the center of the plane of the separation membrane sample 1 in the X-axis direction from among the four reference points P1 to P4 set on the upper surface of the separation membrane sample 1, and forming parallel imaginary vertical lines v1 and v2 that pass through the two selected reference points P2 and P4, respectively. Then, the length L2 of the separation membrane sample 1 in the Y-axis direction may be measured in the second measurement range d2 between the imaginary vertical lines v1 and v2. In this case, the evaluation unit 150 may select the shortest length among the multiple lengths L2 measured within the second measurement range d2 as the measured value L2, as in the case of the first measurement range d1. EXAMPLES

[0042] Hereinafter, a process for evaluating the heat shrinkage rate of a separator using the separator heat shrinkage rate evaluation device 100 according to the present invention will be described.

[0043] First, a separation membrane sample to be evaluated is cut to a predetermined dimension of reference value R, and at least four reference points P1 to P4 are set on the upper surface of the cut separation membrane sample 1 (see FIG. 3).

[0044] Then, the cut separation membrane sample 1 is heated at a predetermined temperature for a predetermined period of time to shrink it.

[0045] Thereafter, the shrunken separation membrane sample 1 is placed on the upper surface of the mounting table 110, and then an image of the separation membrane sample 1 is taken by the photographing unit 140 (see FIG. 2).

[0046] The evaluation unit 150 selects two reference points P1 and P3 that are located closest in the Y-axis direction from the center of the plane of the separation membrane sample 1 among the four reference points P1 to P4 based on the captured image, and then forms parallel imaginary horizontal lines h1 and h2 that pass through the two selected reference points P1 and P3, respectively, and measures the length L1 of the separation membrane sample 1 in the X-axis direction within a first measurement range d1 between the imaginary horizontal lines h1 and h2 (see FIG. 4).

[0047] Additionally, the evaluation unit 150 selects two reference points P2 and P4 that are located closest in the X-axis direction from the center of the plane of the separation membrane sample 1 among the four reference points P1 to P4 based on the captured image, and forms parallel imaginary vertical lines v1 and v2 that pass through the two selected reference points P2 and P4, respectively, and measures the length L2 of the separation membrane sample in the Y-axis direction within a second measurement range d2 between the imaginary vertical lines v1 and v2 (see FIG. 5).

[0048] In this case, the evaluation section 150 can select the shortest lengths among the lengths measured in the first measurement range d1 and the second measurement range d2 as the measurement values ​​L1 and L2 in the X- and Y-axis directions, respectively.

[0049] Finally, the measured length values ​​L1 and L2 in the X- and Y-axis directions are compared with a reference value R (see FIG. 3) to calculate the thermal shrinkage rate.

[0050] The separation membrane heat shrinkage evaluation device 100 according to the present invention, configured as described above, sets first and second measurement ranges d1 and d2 in the X- and Y-axis directions based on four reference points P1 to P4 set on the separation membrane sample 1 forming a rectangular shape, and measures the shortest lengths of the separation membrane sample 1 within those measurement ranges, L1 and L2, respectively, and compares them with a reference value R, thereby measuring the heat shrinkage rate and obtaining more accurate data.

[0051] Although the present invention has been illustrated and described above by way of specific examples, it is of course possible to change and modify the present invention in various ways without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0052] 1: Separation membrane sample, L1, L2: Measured values P1~P4: Reference points, R: Reference value d1: First measurement range, d2: Second measurement range h1, h2: virtual horizontal lines, v1, v2: virtual vertical lines 100: heat shrinkage evaluation device, 110: mounting stand 120: lighting section, 121: first lighting section 122: Second lighting section, 140: Photography section 150: Evaluation section

Claims

1. A stand on which a separation membrane sample to be evaluated is placed; An illumination unit that irradiates light toward at least one of the top surface and the bottom surface of the separation membrane sample; An imaging unit for imaging the separation membrane sample; and an evaluation unit that measures the length of the separation membrane sample in each of the first and second directions through the image captured by the photographing unit, and compares the measured values ​​with reference values ​​before thermal shrinkage to determine the degree of shrinkage of the separation membrane sample.

2. The separation membrane sample is The apparatus for evaluating a thermal shrinkage rate of a separation membrane according to claim 1 , further comprising: setting at least four reference points constituting a rectangle among a plurality of points indicating a frame boundary of the separation membrane sample.

3. The separation membrane sample is formed in a rectangular shape, The apparatus for evaluating the thermal shrinkage rate of a separation membrane according to claim 2 , wherein the reference point is a vertex of the separation membrane sample.

4. The evaluation unit is a first measurement range that is set by selecting two reference points that are disposed closest to a center of a plane of the separation membrane sample in the second direction, i.e., the Y-axis direction, from the four reference points, forming parallel imaginary horizontal lines that pass through the two selected reference points, and measuring the length of the separation membrane sample in the first direction, i.e., the X-axis direction, within a range between the imaginary horizontal lines; a second measurement range in which two reference points that are disposed closest to a center of the plane of the separation membrane sample in the X-axis direction are selected from the four reference points, parallel imaginary vertical lines are formed passing through the two selected reference points, and the length of the separation membrane sample in the Y-axis direction is measured within a range between the imaginary vertical lines; 3. The separation membrane heat shrinkage rate evaluation device according to claim 2, which judges the degree of shrinkage of the separation membrane sample.

5. The evaluation unit is The device for evaluating a thermal shrinkage rate of a separation membrane according to claim 4 , wherein the shortest length among a plurality of lengths measured within the first measurement range and the second measurement range is selected as the measured value.

6. The evaluation unit is The apparatus for evaluating the thermal shrinkage rate of a separation membrane according to claim 1 , wherein the separation membrane sample is recognized by utilizing a difference in brightness or gray scale of the captured image.

7. The illumination unit includes: A first illumination unit is provided under the mounting table and irradiates light toward a bottom surface of the separation membrane sample; 2 . The device for evaluating a thermal shrinkage rate of a separation membrane according to claim 1 , further comprising: a second illumination unit provided above the mounting table and configured to irradiate light toward an upper surface of the separation membrane sample.

8. The first illumination unit is The separator heat shrinkage evaluation device according to claim 7 , which is inserted into the mounting table as a unit and irradiates light toward the entire area of ​​the mounting table.

9. The imaging unit includes: The separator heat shrinkage evaluation device according to claim 1 , further comprising an upper side of the mounting table.

10. A first step of cutting a separation membrane sample to be evaluated to a predetermined reference value and setting at least four reference points on an upper surface of the cut separation membrane sample; A second step of shrinking the separation membrane sample by applying heat at a predetermined temperature for a predetermined time; a third step of placing the shrunken separation membrane sample on an upper surface of a mounting table and then taking an image of the separation membrane sample; a fourth step of selecting two of the four reference points that are located closest to a center of the plane of the separation membrane sample in a Y-axis direction from the center of the plane of the separation membrane sample based on the captured image, forming parallel imaginary horizontal lines that pass through the two selected reference points, and measuring a length of the separation membrane sample in the X-axis direction within a range between the imaginary horizontal lines; a fifth step of selecting two of the four reference points that are located closest to a center of the plane of the separation membrane sample in the X-axis direction from the center of the plane of the separation membrane sample based on the captured image, forming parallel imaginary vertical lines that pass through the two selected reference points, and measuring a length of the separation membrane sample in the Y-axis direction within a range between the imaginary vertical lines; and a sixth step of calculating a thermal shrinkage rate by comparing the measured length values ​​in the X-axis and Y-axis directions with reference values.

11. In the fourth step and the fifth step, The method for evaluating a heat shrinkage rate of a separator according to claim 10, wherein the shortest length among the lengths measured in the X-axis and Y-axis directions is selected as the measured value.

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