Battery powder cohesiveness testing method

Abstract

The invention discloses a method for testing the internal cohesiveness of battery powder. The method comprises the following steps: determining a first bonding area and a first non-bonding area on a first stretching piece; bonding the first bonding area with a pole piece, and then stripping the first bonding area from the pole piece so as to transfer the battery powder on the pole piece to the first bonding area; determining a second bonding area and a second non-bonding area on the second stretching piece; the second bonding area is bonded with the first bonding area, and the battery powder is bonded between the first bonding area and the second bonding area; fixing and pulling the first non-adhesive area and the second non-adhesive area to tear the battery powder, and recording stripping parameters in the tearing process. According to the method for testing the internal cohesiveness of the battery powder, testing and evaluation of the cohesiveness between the powder can be achieved, and a new reference index is provided for testing the cohesiveness of a pole piece.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a method for testing the internal cohesion of battery powder. Background Art

[0002] Lithium-ion batteries have the advantages of high energy sealing, long life, and environmental friendliness, and are widely used in the field of secondary batteries. Existing lithium-ion battery materials mainly include positive electrode sheets, negative electrode sheets, separators, electrolytes, etc., among which the electrode sheets include current collectors, active materials, etc. In order to ensure the operating performance of lithium-ion batteries, lithium-ion batteries need to be subjected to adhesion tests of the electrode sheets. However, the adhesion tests in related technologies are mostly only tests of the adhesion between powder and current collector, and fail to characterize the adhesion performance between powder and powder. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, an embodiment of the present invention proposes a method for testing the internal adhesion of battery powders, which can test and evaluate the bonding performance between powders and provide a new reference indicator for the adhesion test of pole pieces.

[0005] The battery powder internal cohesion testing method of the embodiment of the present invention comprises the following steps:

[0006] Determining a first bonding area and a first non-bonding area on the first tensile member;

[0007] Bonding the first bonding area to the pole piece, and then peeling the first bonding area from the pole piece to transfer the battery powder on the pole piece to the first bonding area;

[0008] defining a second bonding area and a second non-bonding area on the second tensile member;

[0009] Bonding the second bonding area to the first bonding area, with the battery powder being bonded between the first bonding area and the second bonding area;

[0010] The first non-adhesive area and the second non-adhesive area are fixed and pulled to tear the battery powder, and the peeling parameters during the tearing process are recorded.

[0011] In some embodiments, the length dimension of the first bonding area is the same as the length dimension of the first non-bonding area;

[0012] And / or, the length dimension of the second bonding area is the same as the length dimension of the second non-bonding area.

[0013] In some embodiments, the length of the first bonding area and the second bonding area is not less than 50 mm;

[0014] And / or, the peeling parameter is peeling force.

[0015] In some embodiments, before peeling the first bonding area and the pole piece, the following steps are also included:

[0016] Rolling the first bonding area and the pole piece multiple times;

[0017] During the stripping process, the current collector of the pole piece and the battery powder are separated.

[0018] In some embodiments, after bonding the second bonding area to the first bonding area, the following steps are further included:

[0019] The first bonding area and the second bonding area are rolled multiple times to make the battery powder fully adhere to the first bonding area and the second bonding area.

[0020] In some embodiments, when the first non-adhesive area and the second non-adhesive area are pulled, the angle formed by the first non-adhesive area and the second non-adhesive area is 180 degrees, and the whole formed by the first adhesive area, the battery powder, and the second adhesive area is located on the same side of the first non-adhesive area and the second non-adhesive area.

[0021] In some embodiments, the first stretching member and the second stretching member are both double-sided tapes.

[0022] In some embodiments, a release paper is bonded to one side of the double-sided tape, the first non-bonding area and the second non-bonding area are formed by bending and bonding the double-sided tape, and the release paper is coated on the outside of the bent and bonded part of the double-sided tape.

[0023] In some embodiments, a release paper is bonded to one side of the double-sided tape, and before tearing the battery powder, the release paper on the first bonding area and the second bonding area is removed.

[0024] In some embodiments, before tearing the battery powder, the whole formed by the first stretching member and the second stretching member is cut so that the width dimension of the whole formed by the first bonding area and the second bonding area is within a set threshold.

[0025] Beneficial effects: The battery powder internal adhesion testing method of the embodiment of the present invention can test and evaluate the adhesion performance between powders, and provides a new reference index for the adhesion test of pole pieces. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of the first tensile member according to an embodiment of the present invention.

[0027] Figure 2 It is a schematic diagram of the battery powder bonding to the first tensile member according to an embodiment of the present invention.

[0028] Figure 3 It is a schematic diagram of the overall structure formed by the first stretching member, battery powder, and the second stretching member of an embodiment of the present invention.

[0029] Figure 4 Schematic diagram of stretching a first tensile member and a second tensile member by a tensile machine according to an embodiment of the present invention.

[0030] Figure 5 Schematic diagram of a double-sided tape according to an embodiment of the present invention.

[0031] Reference numerals:

[0032] 1-first stretching member; 11-first bonding area; 12-first non-bonding area;

[0033] 2-Battery powder;

[0034] 3-second stretching member; 31-second bonding area; 32-second non-bonding area;

[0035] 4- Upper clamp;

[0036] 5-Lower clamp;

[0037] 6-double-sided tape; 61-first zone; 62-second zone; 63-third zone. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0039] The battery powder internal cohesion testing method of the embodiment of the present invention comprises the following steps:

[0040] S1: Determine a first bonding area 11 and a first non-bonding area 12 on the first stretchable member 1. For example, Figure 1 As shown, the first stretching member 1 can be a long strip as a whole. Along the extension direction of the first stretching member 1, the first stretching member 1 can be divided into two areas. Both areas can be rectangular. The two areas are respectively a first bonding area 11 and a first non-bonding area 12.

[0041] The first adhesive region 11 may be provided with adhesives, etc., so that the first adhesive region 11 can be bonded to other objects. The first non-adhesive region 12 exhibits non-adhesive properties, and is mainly used for clamping and fixing.

[0042] S2: Bonding the first bonding area 11 to the pole piece, and then peeling the first bonding area 11 from the pole piece to transfer the battery powder 2 on the pole piece to the first bonding area 11 .

[0043] For example, the pole piece may include a current collector and a battery powder 2, and the battery powder 2 may be bonded to the current collector. Specifically, the battery powder 2 may be an active material of a battery. The first bonding area 11 of the first stretching member 1 may be directly bonded to the pole piece, thereby achieving adhesion between the battery powder 2 and the first bonding area 11. Then, part or all of the battery powder 2 may be separated from the current collector by manual peeling or the like, thereby achieving transfer of the battery powder 2 from the pole piece to the first stretching member 1. Specifically, Figure 2 shown.

[0044] S3: Determine the second adhesive area 31 and the second non-adhesive area 32 on the second stretching member 3. For example, the second stretching member 3 may also be in the shape of a long strip, and along the extension direction of the second stretching member 3, the second stretching member 3 may also be divided into two areas, both of which may also be rectangular, namely the second adhesive area 31 and the second non-adhesive area 32.

[0045] S4: Bonding the second bonding area 31 to the first bonding area 11 , so that the battery powder 2 is bonded between the first bonding area 11 and the second bonding area 31 .

[0046] For example, Figure 3 As shown, the second bonding area 31 can be arranged opposite to the first bonding area 11 in the up-down direction, the battery powder 2 can be bonded to the upper side of the first bonding area 11, and the second bonding area 31 can be bonded to the upper side of the battery powder 2. The first bonding area 11, the battery powder 2, and the second bonding area 31 form a sandwich structure as a whole.

[0047] S5: Fix and pull the first non-adhesive area 12 and the second non-adhesive area 32 to tear the battery powder 2, and record the peeling parameters during the tearing process.

[0048] For example, Figure 4 As shown, the tensile test can be implemented with the help of a tensile machine, which can include an upper clamp 4 and a lower clamp 5, and the upper clamp 4 can be located directly above the lower clamp 5. During operation, the first non-bonding area 12 can be clamped and fixed by the upper clamp 4, and the second non-bonding area 32 can be clamped and fixed by the lower clamp 5.

[0049] Then the upper clamp 4 and the lower clamp 5 can be driven away. As the upper clamp 4 and the lower clamp 5 continue to move away, the battery powder 2 can be gradually torn apart. The peeling parameter can be the peeling force. According to the action force and the reaction force, it can be concluded that the peeling force of tearing the battery powder 2 is roughly consistent with the action force applied to the upper clamp 4 and the lower clamp 5. Therefore, the real-time recording of the peeling parameters can be achieved by recording the size of the action force applied to the upper clamp 4 or the lower clamp 5.

[0050] In some other embodiments, the stripping parameter may also be pressure, etc. In this case, the stripping force obtained above can be obtained by dividing the width dimension of the battery powder 2 in the front-to-back direction, thereby reducing the influence of other factors on the size of the obtained stripping parameter.

[0051] The method for testing the internal adhesion of battery powders in an embodiment of the present invention can test and evaluate the adhesion performance between powders, thereby providing a new reference index for the adhesion test of pole pieces, and facilitating the overall judgment of the adhesion performance of pole pieces, etc. through various indicators, thereby facilitating the setting and improvement of the processing technology during battery production, and ensuring the good operation of the processed finished batteries.

[0052] In some embodiments, the length dimension of the first bonding area 11 is the same as the length dimension of the first non-bonding area 12. Figure 3 As shown, the length dimension of the first bonding area 11 may be the dimension of the first bonding area 11 in the left-right direction, and the length dimension of the first non-bonding area may be the dimension of the first non-bonding area in the up-down direction, and the two dimensions may be substantially the same.

[0053] Therefore, the lengths of the first bonding area 11 and the first non-bonding area 12 can be adapted to each other, which not only facilitates the clamping and fixing of the non-bonding area, but also enables the length of the bonding area to fully meet the tearing requirements of the test.

[0054] In some embodiments, the length dimension of the second bonding area 31 is the same as the length dimension of the second non-bonding area 32. Figure 3 As shown, the length dimension of the second bonding area 31 may be the dimension of the second bonding area 31 in the left-right direction, and the length dimension of the second non-bonding area may be the dimension of the second non-bonding area in the up-down direction, and the two dimensions may be substantially the same.

[0055] Therefore, the lengths of the first bonding area 11 and the first non-bonding area 12 can be adapted to each other, which not only facilitates the clamping and fixing of the non-bonding area, but also enables the length of the bonding area to fully meet the tearing requirements of the test.

[0056] In some embodiments, the length dimensions of the first bonding area 11 and the second bonding area 31 are not less than 50 mm. This length dimension can also be regarded as the length dimension of the battery powder 2, that is, the length dimension of the battery powder 2 is not less than 50 mm. Specifically, during the tearing process of the battery powder 2, within the first 25 mm of the torn length, the peeling force usually has a large fluctuation, and by limiting the length dimension of the battery powder 2 to not less than 50 mm, the accuracy of the test results can be fully guaranteed.

[0057] In some embodiments, in the above step S2, and before the first bonding area 11 and the pole piece are peeled off, the following steps are also included:

[0058] S21: Rolling the first bonding area 11 and the pole piece multiple times. For example, the first bonding area 11 and the pole piece may be rolled back and forth by a roller for more than three times, thereby ensuring that the first bonding area 11 and the battery powder 2 on the pole piece are fully bonded.

[0059] S22: Separate the current collector of the electrode from the battery powder 2 during the peeling process. It should be noted that the structural strength of the adhesion between the first bonding area 11 and the battery powder 2 may be greater than the bonding strength between the current collector and the battery powder 2. During the peeling process, the current collector may be peeled off from the battery powder 2 manually.

[0060] In some embodiments, in step S4, after the second bonding area 31 is bonded to the first bonding area 11, the following steps are further included:

[0061] S41: Roll the first bonding area 11 and the second bonding area 31 multiple times to fully bond the battery powder 2 to the first bonding area 11 and the second bonding area 31. For example, the first bonding area 11, the battery powder 2, and the second bonding area 31 may be rolled back and forth by a pressure roller multiple times, specifically three times, four times, etc., to ensure that the first bonding area 11, the battery powder 2, and the second bonding area 31 are fully bonded.

[0062] In some embodiments, when the first non-adhesive area 12 and the second non-adhesive area 32 are pulled, the angle formed by the first non-adhesive area 12 and the second non-adhesive area 32 is 180 degrees, and the whole formed by the first adhesive area 11, the battery powder 2, and the second adhesive area 31 is located on the same side of the first non-adhesive area 12 and the second non-adhesive area 32.

[0063] For example, Figure 4As shown, during the pull test, the first non-bonding area 12 can be clamped and fixed by the upper clamp 4, and the second non-bonding area 32 can be clamped and fixed by the lower clamp 5. The first non-bonding area 12 and the second non-bonding area 32 are generally located in the same vertical plane, that is, the angle formed by the first non-bonding area 12 and the second non-bonding area 32 is generally 180 degrees. The sandwich structure formed by the first bonding area 11, the battery powder 2, and the second bonding area 31 can be located on the right side of the first non-bonding area 12 and the second non-bonding area 32.

[0064] In some embodiments, the first stretching member 1 and the second stretching member 3 are both double-sided adhesive tapes 6. This facilitates material acquisition and fully meets the use requirements of the strength of bonding with the battery powder 2.

[0065] In some embodiments, a release paper is bonded to one side of the double-sided tape 6, and the first non-bonding area 12 and the second non-bonding area 32 are both formed by bending and bonding the double-sided tape 6, and the release paper is coated on the outside of the bent and bonded part of the double-sided tape 6.

[0066] For example, Figure 5 As shown, the double-sided adhesive tape 6 can be in the shape of a long strip, and the double-sided adhesive tape 6 can be divided into three zones along the length direction, namely the first zone 61, the second zone 62 and the third zone 63, wherein the second zone 62 is connected between the first zone 61 and the third zone 63, and the length dimensions of the first zone 61, the second zone 62 and the third zone 63 are substantially the same.

[0067] The release paper can be pasted only on one side of the double-sided adhesive tape 6. During processing, the third area 63 can be folded toward the second area 62 and bonded to the second area 62. The second area 62 and the third area 63 after bonding form the first non-bonding area 12 or the second non-bonding area 32. At this time, the release paper can be located outside the second area 62 and the third area 63, so that the first non-bonding area 12 and the second non-bonding area 32 are non-bonding. The first area 61 that has not been processed constitutes the first bonding area 11 or the second bonding area 31, thereby meeting the use requirements of bonding with the battery powder 2.

[0068] In some embodiments, a release paper is bonded to one side of the double-sided adhesive tape 6, and before tearing the battery powder 2, the release paper of the first bonding area 11 and the second bonding area 31 is removed. Specifically, the release paper itself has a high structural strength, and removing the release paper of the first bonding area 11 and the second bonding area 31 can eliminate the influence of the release paper on the test, thereby improving the accuracy of the test results.

[0069] In some embodiments, before tearing the battery powder 2 , the whole formed by the first stretching member 1 and the second stretching member 3 is cut so that the width dimension of the whole formed by the first bonding area 11 and the second bonding area 31 is within a set threshold.

[0070] For example, the overall width of the double-sided tape 6 can be 50 mm, etc. During processing, it can be cut along the center line of the whole formed by the first tensile member 1 and the second tensile member 3 (along the length direction of the tensile member), so that two tensile test samples with a width of approximately 25 mm can be processed, which is conducive to achieving the unification of various indicators of different tensile tests.

[0071] A specific example of a method for testing the internal cohesion of battery powder according to an embodiment of the present invention is described below.

[0072] (1) Fold the double-sided adhesive tape X (which can be regarded as the first stretching member) at 1 / 3 (retain the release paper) so that the third area of ​​the double-sided adhesive tape is adhered to the second area of ​​the double-sided adhesive tape X, and leave 1 / 3 (the first area) of the double-sided adhesive tape X unadhered. The length of the double-sided adhesive tape X after bonding must be greater than 100 mm, that is, the lengths of the first area and the second area must both be greater than 50 mm.

[0073] (2) The first area of ​​the double-sided adhesive X is adhered to the electrode, and the electrode adhered to the double-sided adhesive is rolled back and forth with a pressure roller for three times to peel off the double-sided adhesive, so that the current collector and the battery powder are separated, and the double-sided adhesive X with the battery powder is retained.

[0074] (3) Prepare a double-sided tape Y of the same size and type, fold the double-sided tape Y at 1 / 3 (keep the release paper), so that the third area of ​​the double-sided tape Y is glued to the second area of ​​the double-sided tape Y, and leave 1 / 3 of the double-sided tape Y (the first area) unbonded. The length of the double-sided tape Y after bonding must be greater than 100 mm, that is, the lengths of the first and second areas must both be greater than 50 mm.

[0075] (4) Stick the first area of ​​double-sided tape Y to the side of double-sided tape X with battery powder (first area), and use a pressure roller to naturally roll the double-sided tape (X+Y) back and forth 3 times.

[0076] (5) The double-sided adhesive tape (X+Y) is cut into samples with a width of 25 mm, and the release paper of the double-sided adhesive tape (X+Y) with the battery powder is cut off. The other section is folded into 180° and clamped on the upper and lower clamps of the tensile machine respectively. Then the peeling and stretching speed is set, and the stretching is performed, and the peeling force N is recorded. The peeling force N is the bonding performance value between the powders. After testing, the values ​​of the bonding performance values ​​(peeling force N) between the powders recorded in this embodiment are 0.466N, 0.445N, and 0.453N. This meets the actual needs of evaluating the intrinsic bonding performance between the powders.

[0077] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0078] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0079] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0080] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0081] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0082] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for testing the internal cohesion of battery powder, characterized in that: The following steps are involved: Determining a first bonding area and a first non-bonding area on the first tensile member; Bonding the first bonding area to the pole piece, and then peeling the first bonding area from the pole piece to transfer the battery powder on the pole piece to the first bonding area; defining a second bonding area and a second non-bonding area on the second tensile member; Bonding the second bonding area to the first bonding area, with the battery powder being bonded between the first bonding area and the second bonding area; The first non-adhesive area and the second non-adhesive area are fixed and pulled to tear the battery powder, and the peeling parameters during the tearing process are recorded.

2. The method for testing internal cohesion of battery powder according to claim 1, characterized in that: The length dimension of the first bonding area is the same as the length dimension of the first non-bonding area; And / or, the length dimension of the second bonding area is the same as the length dimension of the second non-bonding area.

3. The method for testing internal cohesion of battery powder according to claim 1, characterized in that: The lengths of the first bonding area and the second bonding area are not less than 50 mm; And / or, the peeling parameter is peeling force.

4. The method for testing internal cohesion of battery powder according to claim 1, characterized in that: Before peeling the first bonding area and the pole piece, the method further includes the following steps: Rolling the first bonding area and the pole piece multiple times; During the stripping process, the current collector of the pole piece and the battery powder are separated.

5. The method for testing internal cohesion of battery powder according to claim 1, characterized in that: After bonding the second bonding area to the first bonding area, the following steps are also included: The first bonding area and the second bonding area are rolled multiple times to make the battery powder fully adhere to the first bonding area and the second bonding area.

6. The method for testing internal cohesion of battery powder according to claim 1, characterized in that: When the first non-adhesive area and the second non-adhesive area are pulled, the angle formed by the first non-adhesive area and the second non-adhesive area is 180 degrees, and the whole formed by the first adhesive area, the battery powder, and the second adhesive area is located on the same side of the first non-adhesive area and the second non-adhesive area.

7. The method for testing internal cohesion of battery powder according to any one of claims 1 to 6, characterized in that: The first stretching member and the second stretching member are both double-sided adhesive tapes.

8. The method for testing internal cohesion of battery powder according to claim 7, characterized in that: A release paper is bonded to one side of the double-sided tape, the first non-bonding area and the second non-bonding area are both formed by bending and bonding the double-sided tape, and the release paper is coated on the outside of the bent and bonded part of the double-sided tape.

9. The method for testing internal cohesion of battery powder according to claim 7, characterized in that: One side of the double-sided adhesive tape is bonded with release paper, and before tearing the battery powder, the release paper on the first bonding area and the second bonding area is removed.

10. The method for testing internal cohesion of battery powder according to claim 7, characterized in that: Before tearing the battery powder, the whole formed by the first stretching member and the second stretching member is cut so that the width dimension of the whole formed by the first bonding area and the second bonding area is within a set threshold.

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