Physical property measurement device for electrodes and / or separation membranes

Abstract

A measuring apparatus for electrodes and / or separator membranes for secondary batteries according to one embodiment of the present invention includes a container with a main body capable of housing a test piece and an electrolyte, and a measuring unit for measuring the physical properties of the test piece, wherein the test piece is at least one of an electrode and a separator membrane for secondary batteries, and the measurement is performed with the test piece impregnated in the electrolyte.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of priority based on Korean Patent Application No. 10 - 2023 - 0078300 filed on June 19, 2023 and Korean Patent Application No. 10 - 2024 - 0072521 filed on June 3, 2024, and all the contents disclosed in the documents of the Korean patent applications are included as part of this specification.

[0002] The present invention relates to an apparatus for measuring physical properties of an electrode and / or a separator membrane, and particularly to an apparatus for measuring physical properties of an electrode and / or a separator membrane for a secondary battery in a state where the electrode and / or the separator membrane for the secondary battery is impregnated with an electrolyte solution.

Background Art

[0003] A secondary battery is a battery capable of charging and discharging. Secondary batteries are used in portable small electronic devices such as mobile phones and laptop computers, or widely used as power sources for motor drives such as power tools and automobiles. The inside of a secondary battery may be composed of a positive electrode, a negative electrode, a separator membrane, an electrolyte, etc., and the case may be made of a metal plate or a pouch.

[0004] According to the prior art, in the case of tension, compression, punching, etc. of an electrode and / or a separator membrane, when measuring physical properties, test pieces of the electrode and / or the separator membrane were tested in a dry state. However, in the case of a secondary battery using a liquid electrolyte (electrolyte solution), the electrodes and separator membranes in an actual secondary battery exist in a state impregnated with the electrolyte solution. Therefore, the polymer (electrode binder, separator membrane) is softened by the electrolyte solution, and the physical properties (mechanical behavior properties) of the secondary battery change due to the penetration (impregnation) of the electrolyte solution into the pores of the electrode and the separator membrane.

[0005] Therefore, in order to more accurately evaluate the manufacturing processability and performance of secondary batteries, there is currently a need for technology that can create a model that closely resembles the actual conditions / environment of the electrodes and separator membrane of a secondary battery, and that can measure the physical properties of the electrodes and / or separator membrane. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention aims to provide an apparatus for measuring the physical properties of an electrode and / or separation membrane for a secondary battery while the electrode and / or separation membrane are impregnated in an electrolyte.

[0007] However, the problems that the embodiments of the present invention aim to solve are not limited to those described above, and can be broadly extended within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0008] A measuring apparatus for electrodes and / or separator membranes for secondary batteries according to one embodiment of the present invention includes a container with a main body capable of housing a test piece and an electrolyte, and a measuring unit for measuring the physical properties of the test piece, wherein the test piece is at least one of an electrode and a separator membrane for secondary batteries, and the measurement is performed with the test piece impregnated in the electrolyte.

[0009] The container may include at least one of an electrolyte inlet located at the top and an electrolyte outlet located at the bottom.

[0010] The container may include an observation window that allows the inside of the container to be viewed.

[0011] The container further includes a door that can open and close the main body, the door including an opening, and the opening may be provided with the observation window.

[0012] The container may further include a sealing member provided between the container body and the door to prevent leakage of the electrolyte.

[0013] The system may further include a locking device for securing the door to the main body of the container when the door is closed.

[0014] The container further includes a bar that penetrates the top surface and is movable toward or toward the test specimen, and the movement of the bar can pull or press the test specimen.

[0015] The end of the bar is provided with a pair of grippers that grip both ends of the test piece, and one of the pair of grippers may be detachably coupled to the end of the bar, while the other of the pair of grippers may be detachably coupled to the lower surface inside the body of the container.

[0016] The end of the bar is provided with a press-fit member that is detachably connected, and the lower surface inside the main body of the container is provided with a specimen mounting member that is detachably connected, the press-fit member includes a tip, and the specimen mounting member includes a specimen mounting portion in the shape of a recess provided in the center of the upper end, and the center of the specimen can be separated from the specimen mounting portion.

[0017] The end of the bar is provided with a compression member that is detachably connected, and the lower surface inside the main body of the container is provided with a test piece mounting member that is detachably connected, the compression member includes a flat compression portion, and the test piece mounting member includes a test piece mounting portion provided at its upper end, the test piece mounting portion may have a flat shape.

[0018] The measurement unit may be a load cell connected to the bar.

[0019] By moving the bar downward and measuring and converting the repulsive force transmitted from the test piece to the bar with the load cell, the tensile force radially generated from the central portion of the test piece can be measured.

[0020] The measurement unit may be a camera unit.

[0021] The displacement of the test piece can be measured by imaging the test piece with the camera unit.

[0022] The camera unit may be a DIC (digital image correlation) camera.

[0023] The image captured by the measurement unit further includes a correction image for correcting errors that may occur due to refraction or reflection of light by the electrolytic solution. The correction image includes a plurality of line segments on a base material as a reference image. Each of the plurality of line segments has the same length and different inclinations. The measurement unit can be corrected by imaging the correction image immersed in the electrolytic solution until all of the plurality of line segments have the same length.

[0024] Each of the plurality of line segments can have an inclination angle that sequentially increases with a peripheral edge of the base material as a reference line.

[0025] At least some of the plurality of line segments may be arranged at substantially equal angles to each other.

[0026] The starting points of at least some of the plurality of line segments may be different from each other, and the ending points of at least some of the plurality of line segments may be different from each other.

[0027] The test piece may be a laminated single cell in which the electrode and the separation membrane are laminated.

Advantages of the Invention

[0028] According to the present invention, in an apparatus for measuring physical properties of an electrode and / or a separator for a secondary battery, since the electrode and / or the separator are measured in a state impregnated with an electrolytic solution, it is possible to test in a state similar to the usage environment of an actual battery cell, and thus the physical properties of the electrode and / or the separator, and / or the battery cell can be evaluated more accurately.

[0029] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Brief Description of the Drawings

[0030] [Figure 1] It is a front view of a physical property measuring apparatus 100 for an electrode and / or a separator according to an embodiment of the present invention. [Figure 2] It shows that an electrolytic solution 20 is stored in the measuring apparatus 100 of FIG. 1. [Figure 3] It is a partially enlarged side view of the measuring apparatus 100 of FIG. 1. [Figure 4] It shows an example of a test piece 10 mounted on the measuring apparatus 100 of FIG. 1. [Figure 5] It shows a state where a camera unit for imaging and measuring the test piece 10 is mounted on the measuring apparatus 100 of FIG. 1. [Figure 6] It shows a camera correction image 310 for correction before measurement by the camera unit of FIG. 5 in the measuring apparatus 100 of FIG. 1. [Figure 7] It is a front view of a physical property measuring apparatus 100 for an electrode and / or a separator according to another embodiment of the present invention. [Figure 8] It shows a state where an electrolytic solution 20 is stored in the measuring apparatus 100 of FIG. 7. [Figure 9] It is an enlarged view of the press-fitting member 220 and the test piece mounting member 230 of FIG. 7. [Figure 10] It shows an example of a test piece 10 mounted on the measuring apparatus 100 of FIG. 7. [Figure 11]This is a front view of an electrode and / or separation membrane physical property measuring device 100 according to yet another embodiment of the present invention. [Figure 12] Figure 11 shows the measuring device 100 with the electrolyte 20 stored inside. [Figure 13] This is an enlarged view of the compression member 240 and the test specimen mounting member 250 shown in Figure 11. [Figure 14] Figure 13 is a front view of the compression member 240. [Figure 15] Figure 13 is a top view of the test specimen mounting member 250. [Figure 16] An example of a test piece 10 to be mounted on the measuring device 100 shown in Figure 11 is presented. [Figure 17] The table shows a comparison of the results when the negative electrode was tested using a dry method according to the comparative example and when it was tested using a wet method according to the embodiment of the present invention. [Figure 18] The table shows a comparison of the results when the positive electrode was tested using a dry method according to the comparative example and when it was tested using a wet method according to the embodiment of the present invention. [Figure 19] The table shows a comparison of the results when the separation membrane was tested using a dry method according to the comparative example and when it was tested using a wet method according to the embodiment of the present invention. [Figure 20] The graphs show comparative examples and examples at the cell level. [Figure 21] Figure 20 shows a table illustrating the maximum load values ​​in the graph. [Modes for carrying out the invention]

[0031] Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings, so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. The present invention can be realized in a variety of different forms and is not limited to the embodiments described herein.

[0032] To clearly explain the present invention, unnecessary explanatory parts have been omitted, and the same or similar reference numerals are used throughout the specification for identical or similar components.

[0033] Furthermore, the dimensions and thicknesses of each component shown in the drawings are arbitrary for illustrative purposes, and the present invention is not necessarily limited to those shown. The thicknesses are enlarged in the drawings to clearly represent various layers and regions. Additionally, the thicknesses of some layers and regions are exaggerated in the drawings for illustrative purposes.

[0034] Furthermore, when we say that a layer, membrane, region, plate, or other part is "on top" of another part, this includes not only the case where it is "directly above" the other part, but also the case where the other part is in between. Conversely, when we say that one part is "directly above" another part, it means that there is no other part in between. Moreover, being "on top" of a reference part means being located above or below the reference part, and does not necessarily mean being located "up" in the opposite direction of gravity.

[0035] Furthermore, when a specification states that a part of it "includes" a certain component, unless otherwise specified, this means that it can further encompass other components rather than excluding them.

[0036] In this specification, "on a plane" refers to the view of the subject from above, and "on a cross-section" refers to the view of a cross-section obtained by cutting the subject perpendicularly, viewed from the side.

[0037] The components of an electrode and / or separation membrane physical property measuring apparatus according to one embodiment of the present invention, and the measurements (tests) performed by the measuring apparatus, will be described below with reference to the drawings.

[0038] Uniaxial tensile test First, Figures 1 to 6 show that a uniaxial tensile test is performed using a physical property measurement device 100 for electrodes and / or separation membranes according to one embodiment of the present invention.

[0039] Figure 1 is a front view of an electrode and / or separation membrane physical property measuring device 100 according to one embodiment of the present invention. Figure 2 shows the measuring device 100 of Figure 1 with the electrolyte 20 contained within it. Figure 3 is a partially enlarged side view of the measuring device 100 of Figure 1. Figure 4 shows a test piece 10 mounted on the measuring device 100 of Figure 1.

[0040] An apparatus 100 for measuring the physical properties of an electrode and / or separation membrane according to one embodiment of the present invention includes a container in which a test piece 10 and an electrolyte 20 are housed. The container includes a main body 110 (hereinafter referred to as the "container body") in which the test piece 10 and the electrolyte 20 are housed, a door 120 located on one side of the body (e.g., the front) that can be opened and closed, a bar 130 that penetrates the top surface of the container body 110 and is movable in the direction toward the test piece 10 and in the opposite direction, an electrolyte inlet 140 provided at the top of the container body 110, and an electrolyte outlet 150 provided at the bottom of the container body 110.

[0041] Unlike conventional dry methods, the present invention is a wet method that allows for the measurement of the properties (such as physical properties) of the electrode and / or separation membrane test piece 10 while it is impregnated in the electrolyte 20. The container body 110 can accommodate not only the test piece 10 but also the electrolyte 20. The container body 110 may be made of, for example, metal or PVC (polyvinyl chloride), but the present invention is not limited thereto, and may be made of a rigid material that has low reactivity with the electrolyte solvent components.

[0042] Once the test specimen 10 is placed in the container body 110, the door 120 is closed. The container body 110 and the door 120 are equipped with a locking device 170 (see Figure 3 for details) that can firmly secure the container body 110 and the door 120 to each other. The door 120 is provided with an observation window 121 that allows the inside of the container body 110 to be viewed. Measurements can be performed while observing the state in which the test specimen 10 and electrolyte 20 are stored through the observation window 121. The door 120 may have an opening, and the observation window 121 may be attached to the opening. To prevent the electrolyte 20 from leaking, a sealing member (not shown) may be additionally included around the opening. The observation window 121 can be made of, for example, tempered glass, but the present invention is not limited thereto, and may be made of a material that has rigidity as a material with low reactivity with the electrolyte solvent components and allows the inside to be seen with the naked eye or camera.

[0043] On the other hand, the present invention is not limited to the illustrated version, and various modifications and changes are possible, such as the observation window 121 being provided on the container body 110 instead of the door 120.

[0044] The electrolyte inlet 140 is provided in the upper part of the container body 110 in the shape of a through-hole, and a pipe (not shown) for supplying the electrolyte 20 is connected to the inside of the container body 110 via the electrolyte inlet 140 to supply the electrolyte 20. The electrolyte outlet 150 is provided in the lower part of the container body 110 in the shape of a through-hole. A pipe 151 and an on / off valve 152 are connected to the electrolyte outlet 150.

[0045] After the test piece 10 is mounted and the door 120 is closed, the electrolyte 20 flows into the container body 110 with the on / off valve 152 closed before measurement. Therefore, the test can be performed on the test piece 10 with the electrolyte 20 inside the container body 110. After the measurement is completed in the wet test, the on / off valve 152 can be opened to discharge the electrolyte 20 to the outside of the container body 110. Alternatively, if a dry test is to be performed, the on / off valve 152 can be opened to discharge the electrolyte 20 to the outside of the container body 110 before the test can be performed.

[0046] An additional sealing member 160 is included between the container body 110 and the door 120. This prevents the electrolyte 20 from leaking into the gap between the container body 110 and the door 120. The sealing member 160 may be provided on the container body 110 as shown in Figure 1, but the present invention is not limited thereto, and various modifications are possible, such as providing it on the door 120.

[0047] The bar 130 is positioned to penetrate the top surface of the container body 110 and is movable toward the test specimen 10 and in the opposite direction. Various components for measurement are attached to the end of the bar 130.

[0048] In the embodiment shown in Figure 1, a uniaxial tensile test of the test specimen 10 is performed, and the ends of the bar 130 are equipped with a pair of grippers 210 capable of gripping both ends of the test specimen 10. One of the pair of grippers 210 is detachably coupled to the end of the bar 130, and the other of the pair of grippers 210 is detachably coupled to the lower interior surface of the container body 110. The test specimen 10 is placed between the pair of grippers 210, and the bar 130 is pulled while moving vertically from the bottom to the top of the container body 110. The displacement of the pulled test specimen 10 can be measured by a camera unit (see Figure 5), which will be described later.

[0049] Figure 3 is a partially enlarged side view of the measuring device 100 shown in Figure 1. A small observation window 180 is additionally provided on the side of the container body 110 to check whether the test piece 10 is properly mounted.

[0050] Figure 4 shows one embodiment of a test specimen 10 provided in the case of a uniaxial tensile test. The test specimen 10 is manufactured, for example, as shown in Figure 4, and can be mounted between a pair of grippers 210.

[0051] To prevent premature fracture of the test specimen 10, the ASTM E345 standard test specimen can be partially modified to have a curvature (e.g., R19mm, R10mm), as shown in Figure 4. However, the present invention is not limited to the illustrated version, and various modifications and changes are possible, such as modifying the dimensions of the entire or partial test specimen 10, or, in the case of uniaxial tensile testing, manufacturing the test specimen 10 in strip or band shape for testing.

[0052] Figure 5 shows the measurement device 100 in Figure 1 with a camera unit attached to image and measure the test piece 10. Figure 6 shows a camera correction image 310 used to correct the camera unit in Figure 5 before measurement in the measurement device 100 of Figure 1.

[0053] In this case, the camera unit corresponds to the measurement unit. The camera unit is positioned at the front of the container body 110. The camera unit may be, for example, a DIC (digital image correlation) camera, and it images the test piece 10 inside the body 110 to measure the displacement of the test piece 10. When the displacement data of the test piece 10 transmitted from the camera unit is input to the computer, the computer's processor converts the displacement value of the test piece 10 into various physical values ​​such as the deformation rate.

[0054] In wet testing, the degree of deformation (e.g., deformation rate) of the test specimen 10 can be difficult to measure with the desired accuracy due to the refraction and reflection of light by the electrolyte 20. Therefore, uniaxial tensile testing of the test specimen 10 impregnated in the electrolyte 20 can be performed using the 2D-DIC (2-dimension-digital image correlation) measurement method. In 2D-DIC measurement, the camera unit and the test specimen 10 are aligned in a straight line.

[0055] Before testing the test piece 10, it is first corrected with the correction image 310 shown in Figure 6 so that the image captured by the camera unit has the actual, accurate length value, not a value that is subject to errors due to the refraction and reflection of light by the electrolyte 20. Figure 6(a) is an example of the correction image 310, and Figure 6(b) shows the correction image 310 mounted between the pair of grippers 210 in Figure 1.

[0056] The correction image 310 is placed between the pair of grippers 210 shown in Figure 1, and the correction image 310 is positioned inside the container body 110. The inside of the container body 110 is filled with electrolyte 20. Subsequently, the camera position is adjusted until the length values ​​of all line segments placed on the correction image 310, which will serve as the reference image, are the same.

[0057] The correction image 310 in Figure 6 shows, for example, a square plate-shaped base material 311 with multiple line segments 312 arranged on it. First, each of the multiple line segments (312; 312-1, 312-2, 312-3, ..., 312-k, 312-k+1, ..., 312-n, where k is a natural number from 1 to n) has the same length. Also, each of the multiple line segments 312 has a different slope (the straight line formed by extending multiple line segments has a different slope).

[0058] In addition, each of the multiple line segments 312 can have an inclination angle that increases sequentially with respect to one periphery of the base material 311 (for example, a horizontal or vertical line). The example in Figure 6 shows an example of the inclination angle when the horizontal line (-x axis) is used as the reference line.

[0059] In this case, at least some of the multiple line segments 312 can have the same difference in the slope angles between adjacent line segments. Figure 6 shows, as an example, that the slope angle of line segment 312-1 is 0 degrees, the slope angle of line segment 312-2 is 15 degrees, the slope angle of line segment 312-3 is 30 degrees, the slope angle of line segment 312-k (k=4) is 45 degrees, and the slope angle of line segment 312-k+1 (k=4) is 60 degrees, increasing sequentially by 15 degrees each time.

[0060] In other words, at least some of the line segments 312 may be arranged at equal angles to each other. This may be more advantageous for correcting errors over a wider range if the difference in the angle of inclination between adjacent line segments 312 is the same (i.e., evenly spaced) than if the line segments 312 are densely spaced within a particular range.

[0061] However, the present invention is not limited to what has been described above. In environments where errors are likely to occur within a specific range of inclination angles, the invention can also be implemented by modifying or changing the method to arrange line segments more densely within that range of inclination angles.

[0062] Furthermore, the starting points of at least some of the line segments 312 may be the same, but they may also be different, as shown in Figure 6. Similarly, the ending points of at least some of the line segments 312 may be the same, but they may also be different, as shown in Figure 6.

[0063] Image correction can be performed over a wider area when the starting points of each of the multiple line segments 312 are all different, and the ending points of each of the multiple line segments 312 are all different. However, the present invention is not necessarily limited to this, and can be modified and implemented in various ways to suit the environment in which the present invention is applied.

[0064] By employing the correction image 310 according to the present invention, the image captured by the camera unit is not affected by the various angles of light incident on the electrolyte 20, enabling accurate measurement of the length value (i.e., displacement value) of the test piece 10.

[0065] Biaxial tensile test Figures 7 to 10 show a biaxial tensile test being performed in the physical property measurement device 100 for electrodes and / or separation membranes according to another embodiment of the present invention.

[0066] Figure 7 is a front view of an electrode and / or separation membrane physical property measuring device 100 according to another embodiment of the present invention. Figure 8 shows the measuring device 100 of Figure 7 with the electrolyte 20 contained within it. Figure 9 is an enlarged view of the press-fitting member 220 and the test piece mounting member 230 of Figure 7. Figure 10 shows a test piece 10 mounted on the measuring device 100 of Figure 7.

[0067] The embodiments shown in Figures 7 to 10 relate to biaxial tensile testing, and the differences from the measuring device 100 for uniaxial tensile testing described in Figure 1 and other figures will be explained in detail.

[0068] In the aforementioned uniaxial tensile test, the case was described in which the test specimen 10 is pulled directly in one axial direction (in the embodiment of Figure 1, the height direction of the container body 110 and the longitudinal direction of the bar 130). However, in the biaxial tensile test in the embodiments of Figures 7 to 10, the biaxial tensile test can be carried out indirectly without directly pulling the test specimen 10 in each of the two axial directions. The test specimen 10 can be measured by applying pressure (punching) to it with a tip and measuring and converting the rebound force of the test specimen 10. In this technical field, "punching" refers not to a method of striking the test specimen in a short time or punching a hole, but rather to applying pressure to the center of the test specimen with a tip in order to generate tensile force radially.

[0069] The test specimen 10 is prepared as a thin film, as shown in Figure 10. Next, it is placed on the test specimen mounting member 230 shown in Figures 7 to 9, and the center of the upper surface of the test specimen 10 is pressed with the press-fitting member 220.

[0070] The press-fit member 220 is detachably connected to the end of the bar 130, and the test piece mounting member 230 is detachably connected to the lower interior surface of the container body 110. In the embodiment of Figure 1, if a biaxial tensile test according to the embodiment of Figure 7 is to be performed after the uniaxial tensile test described above has been completed, the pair of grippers 210 can be removed from the container body 110, and then the press-fit member 220 and the test piece mounting member 230 can be attached.

[0071] The press-fit member 220 includes a connecting portion 222 that can be connected to the end of the bar 130, and a tip 221 which is a tip portion provided at the end of the connecting portion 222. The specimen mounting member 230 includes a main body 232 that can be connected to the lower interior surface of the container body 110, and a specimen mounting portion 231 provided at the center of the upper end of the main body 232. The specimen mounting portion 231 has a recess in its center. In other words, the peripheral edge of the lower surface of the specimen 10 is in contact with the peripheral edge of the specimen mounting portion 231, and the center of the lower surface of the specimen 10 is suspended in mid-air at a predetermined distance from the specimen mounting portion 231.

[0072] The test specimen 10 is placed on the test specimen mounting section 231, and the bar 130 is moved downward to pressurize the center of the upper surface of the test specimen 10 with the tip 221 of the press-fitting member 220. The tip 221 has a relatively pointed tip shape, but its purpose is not to pressurize the test specimen 10 and create a hole in it, but rather to generate tensile force radially from the tip 221 that is pressing the test specimen 10. The center of the lower surface of the test specimen 10 is separated from the test specimen mounting section 231 by a predetermined distance, so the center of the test specimen 10 bends downward along the direction of pressure from the tip 221. At this time, tensile force is generated radially from the tip 221 that is pressing the test specimen 10, so the biaxial tensile test can be carried out. In addition, a repulsive force is generated in the opposite direction to the direction in which the test specimen 10 is pressed from above by the tip 221. Instead of directly measuring the radially generated tensile force (biaxial tensile force), the biaxial tensile test can be carried out by measuring the repulsive force against the force applied by the tip 221 and converting it. A load cell 400 is attached to the upper end of the bar 130. Therefore, the repulsive force transmitted to the bar 130 can be measured. In this case, the load cell 400 corresponds to the measuring unit.

[0073] The press-fit member 220 may be made of, for example, Teflon® material to reduce the effects of frictional force, but the present invention is not limited thereto, and materials suitable for the environment in which the present invention is implemented can be used.

[0074] In the embodiments shown in Figures 7 to 10, which relate to biaxial tensile testing, the explanation of components that overlap with the components of the measuring device 100 for uniaxial tensile testing described in Figures 1 to 6 is omitted, and the above information is to be referenced.

[0075] Compression test Figures 11 to 16 show a compression test being performed in an electrode and / or separation membrane physical property measuring device 100 according to yet another embodiment of the present invention.

[0076] Figure 11 is a front view of an electrode and / or separation membrane physical property measuring device 100 according to yet another embodiment of the present invention. Figure 12 shows the measuring device 100 of Figure 11 with the electrolyte 20 contained within it. Figure 13 is an enlarged view of the compression member 240 and the test piece mounting member 250 of Figure 11. Figure 14 is a front view of the compression member 240 of Figure 13, and Figure 15 is a top view of the test piece mounting member 250 of Figure 13. Figure 16 shows a test piece 10 mounted in the measuring device 100 of Figure 11.

[0077] The embodiments shown in Figures 11 to 16 relate to compression testing, and the differences from the measuring device 100 for the uniaxial tensile and biaxial tensile tests described above will be emphasized.

[0078] In the embodiment of the compression test shown in Figures 11 to 16, the test piece 10 is placed on the test piece mounting member 250, and the entire upper surface of the test piece 10 is compressed with the compression member 240.

[0079] The compression member 240 is detachably connected to the end of the bar 130, and the specimen mounting member 250 is detachably connected to the lower interior surface of the container body 110. When performing a compression test according to this embodiment after completing the uniaxial tensile test described above in the embodiment of Figure 1, the pair of grippers 210 can be removed from the container body 110, and then the compression member 240 and the specimen mounting member 250 can be attached. Alternatively, after completing the biaxial tensile test described above in the embodiment of Figure 7, the press-fit member 220 and the specimen mounting member 230 can be removed, and then the compression member 240 and the specimen mounting member 250 can be attached.

[0080] The compression member 240 includes a connecting portion 242 that can be connected to the end of the bar 130, and a flat-shaped compression portion 241 provided at the end of the connecting portion 242.

[0081] In the measuring device 100 in the embodiment for the biaxial tensile test shown in Figure 7, the bar is moved downward to pressurize the test piece 10 with the press-fitting member 220, and in the measuring device 100 in the embodiment for the compression test shown in Figure 11, the bar is moved downward to pressurize the test piece 10 with the compression member 240. In the case of the biaxial tensile test in Figure 7, the tip 221 of the press-fitting member 220 has a relatively pointed tip shape (however, the end is rounded by a rounding process to prevent premature fracture of the test piece), so it is used to pressurize the center of the thin test piece 10 to generate tensile force radially including biaxially. However, the compression part 241 of the compression member 240 in Figure 11 has a flat shape, so it is possible to perform a compression test by pressing the entire upper surface of a test piece 10 that has volume, for example, a cylindrical test piece 10 (see Figure 16). The test specimen 10 used in the compression test can be manufactured in the shape shown in Figure 16, for example, using a mold making machine and testing machine such as the Instron 5943.

[0082] The specimen mounting member 250 includes a main body 252 that can be coupled to the lower interior surface of the container body 110, and a specimen mounting portion 251 provided at the center of the upper end of the main body 252. The upper surface of the specimen mounting portion 251 also has an overall flat structure. In other words, it differs from the specimen mounting portion 231 which has a recess in the center in the embodiment of the biaxial tensile test shown in Figure 7.

[0083] The upper surface of the test piece 10 is pressed by the flat surface of the compression section 241, and as a result, the lower surface of the test piece 10 is pressed by the flat surface of the test piece mounting section 251, so that the test piece 10 is compressed.

[0084] While the measuring device 100 according to the above-described embodiment of the present invention can also be used to test electrodes and / or separation membranes, various modifications and changes are possible, such as being able to test stacked cell units.

[0085] The following describes comparative examples and examples of the present invention for the anode, cathode, and separation membrane, respectively. The comparative examples are those in which the test specimen 10 is tested dry without impregnation with electrolyte according to the prior art, while the examples of the present invention are those in which the test specimen 10 is impregnated with electrolyte 20 for a predetermined time in the measuring apparatus 100 shown in Figures 1 to 16, and are tested wet.

[0086] negative electrode For uniaxial tensile testing, the test specimen 10 was prepared as shown in Figure 4. For biaxial tensile testing, the test specimen 10 was prepared as a thin section as shown in Figure 10. For compression testing, the test specimen 10 was prepared as shown in Figure 16 by drying a negative electrode active material slurry made of graphite material having a density similar to that of the negative electrode active material slurry coated on the current collector in a cylindrical mold at 120 degrees Celsius. In the wet test, the test specimen 10 was immersed in the electrolyte 20 for a minimum of 20 minutes prior to measurement.

[0087] Figure 17 shows a table comparing the results of a dry test performed on the negative electrode according to the comparative example and a wet test performed according to the embodiment of the present invention. Figures 17(a) and (b) show the results of the uniaxial tensile test, (c) and (d) show the results of the biaxial tensile test, and (e) show the results of the compression test.

[0088] Compared to a dry test, which is a comparative example of the conventional technology, the wet test according to the embodiment of the present invention shows that the tensile modulus of elasticity decreases by approximately 70%, the tensile yield strength decreases by 20-30%, and both the compressive modulus of elasticity and yield strength decrease by approximately 60-70%. In other words, it can be seen that the strength decreases when the test piece 10 is impregnated with the electrolyte 20.

[0089] positive electrode For uniaxial tensile testing, the test specimen 10 was prepared as shown in Figure 4. For biaxial tensile testing, the test specimen 10 was prepared as a thin slice as shown in Figure 10. For compression testing, the test specimen 10 was prepared as shown in Figure 16 by drying a positive electrode active material slurry of NCM material having a density similar to that of the positive electrode active material slurry coated on the current collector in a cylindrical mold at 120 degrees Celsius. In the wet test, the test specimen 10 was immersed in the electrolyte 20 for a minimum of 20 minutes prior to measurement.

[0090] Figure 18 shows a table comparing the results of a dry test performed on the positive electrode according to the comparative example and a wet test performed according to the embodiment of the present invention. Figures 18(a) and (b) show the results of the uniaxial tensile test, (c) shows the results of the biaxial tensile test, and (d) shows the results of the compression test. For reference, in the case of the uniaxial tensile test, MD is an abbreviation for machine direction and TD is an abbreviation for transverse direction.

[0091] Compared to a dry test, which is a comparative example of the conventional technology, the wet test according to the embodiment of the present invention shows that the tensile modulus decreases by approximately 50-60%, the tensile yield strength decreases by 20-30%, and both the compressive modulus and yield strength decrease by approximately 70%. In other words, it can be seen that impregnating the test piece 10 with the electrolyte 20 reduces its strength.

[0092] Separation membrane For uniaxial tensile testing, the test specimen 10 was prepared as shown in Figure 4. For biaxial tensile testing, the test specimen 10 was prepared as a thin section as shown in Figure 10. Polypropylene (PP) was used as the material for the separation membrane. In the wet test, the test specimen 10 was immersed in the electrolyte 20 for a minimum of 20 minutes before measurement.

[0093] Figure 19 shows a table comparing the results of a dry test performed on the separation membrane according to the comparative example and a wet test performed according to the embodiment of the present invention. Figures 19(a) and (b) show the results of the uniaxial tensile test, and (c) shows the results of the biaxial tensile test.

[0094] Figure 20 shows graphs of comparative examples and examples at the cell level. Figure 21 shows a table of maximum load values ​​in the graphs of Figure 20.

[0095] Measurements were taken by pressing multiple electrode stacked test pieces with a press-fitting member 220. Figure 20 is a graph showing the force measured by the load cell as displacement, and Figure 21 shows the peak values ​​in a table. As can be seen from Figure 21(b), in the case of the wet test according to the embodiment of the present invention, the maximum load error rate is about 11%, which is in good agreement with the simulation. If, as can be seen from Figure 21(c), in the case of the dry test, the error rate is about 90%.

[0096] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art that utilize the basic concepts of the present invention as defined in the following claims also fall within the scope of the present invention. [Explanation of symbols]

[0097] 100: Measuring device 110: Container body 120: Door 121: Observation window 130: Bar 140: Electrolyte inlet 150: Electrolyte outlet 160: Sealing components 210: Grippa 220: Press-fit member 230: Test specimen mounting member 240: Compression member 250: Test specimen mounting member 310: Correction image 400: Load cell

Claims

1. A container including a main body capable of housing test specimens and electrolyte, Includes a measuring unit for measuring the physical properties of the test specimen, The test specimen is at least one of an electrode and a separator membrane for a secondary battery, and the measurement is performed with the test specimen impregnated in the electrolyte.

2. The measuring device according to claim 1, wherein the container includes at least one of an electrolyte inlet provided at the top and an electrolyte outlet provided at the bottom.

3. The measuring device according to claim 1, wherein the container includes an observation window that allows the inside of the container to be viewed.

4. The container further includes a door that can open and close the main body, The aforementioned door includes an opening, The measuring device according to claim 3, wherein the opening is provided with the observation window.

5. The measuring device according to claim 4, further comprising a sealing member provided between the body of the container and the door to prevent leakage of the electrolyte.

6. The measuring device according to claim 4, further comprising a locking device for securing the door to the main body of the container when the door is closed.

7. The container further includes a bar that penetrates the top surface and is movable toward or toward the test specimen, The measuring device according to claim 1, wherein the test piece is pulled or compressed by the movement of the bar.

8. The ends of the bar are provided with a pair of grippers that grip both ends of the test piece, The measuring device according to claim 7, wherein one of the pair of grippers is detachably coupled to the end of the bar, and the other of the pair of grippers is detachably coupled to the lower surface inside the main body of the container.

9. The end of the bar is provided with a press-fit member that is detachably connected, The container is provided with a test piece mounting member that is detachably attached to the lower surface inside the main body of the container, The press-fitting member includes a tip, and the specimen mounting member includes a specimen mounting portion with a recessed shape provided at the center of the upper end. The measuring device according to claim 7, wherein the central part of the test specimen is separated from the test specimen mounting portion.

10. The end of the bar is provided with a compression member that is detachably connected, The container is provided with a test piece mounting member that is detachably attached to the lower surface inside the main body of the container, The compression member includes a flat compression portion, and the test piece mounting member includes a test piece mounting portion provided at its upper end. The measuring device according to claim 7, wherein the test piece mounting portion has a flat shape.

11. The measuring device according to claim 7, wherein the measuring unit is a load cell connected to the bar.

12. The measuring device according to claim 11, wherein the bar moves downward and the repulsive force transmitted from the test piece to the bar is measured and converted by the load cell, thereby measuring the tensile force generated radially from the center of the test piece.

13. The measuring device according to claim 1, wherein the measuring unit is a camera unit.

14. The measuring device according to claim 13, wherein the camera unit captures an image of the test piece and measures the displacement of the test piece.

15. The measuring device according to claim 13, wherein the camera unit is a DIC (Digital Image Correlation) camera.

16. The image captured by the measurement unit further includes a correction image for correcting errors that may occur due to the refraction and reflection of light by the electrolyte, The correction image includes a plurality of line segments on the substrate as a reference image, and each of the plurality of line segments has the same length and a different inclination. The measuring device according to claim 1, wherein the measuring unit captures the correction image immersed in the electrolyte, and corrects the measuring unit until all of the plurality of line segments have the same length.

17. The measuring device according to claim 16, wherein each of the plurality of line segments has an inclination angle that increases sequentially with respect to one periphery of the substrate as a reference line.

18. The measuring device according to claim 17, wherein at least some of the line segments are arranged at equal angles to each other.

19. The starting points of at least some of the line segments mentioned above are different. The measuring device according to claim 16, wherein the endpoints of at least some of the line segments are different.

20. The measuring device according to claim 1, wherein the test specimen is a stacked cell in which the electrodes and the separation membrane are stacked.

Images