CN115078064A - Testing device and testing method for tensile shrinkage rate of lithium battery diaphragm - Google Patents

Abstract

The invention belongs to the technical field of battery production and manufacture, and in particular relates to a testing device for the tensile retraction rate of a lithium battery diaphragm, comprising a tension machine, a crossbar and a platform; a first gripper and a second gripper, respectively Installed on the tensile machine; one end of the first clamp is connected to the cross bar, the other end of the first clamp clamps the upper end of the diaphragm to be measured, and one end of the second clamp clamps Hold the lower end of the diaphragm to be tested, and the other end of the second holder is connected to the platform; the fixing plate and the reference ruler, the first holder fixes the upper end of the fixing plate, and the fixing plate is located on the two sides. Between the first holder and the second holder, the reference ruler is arranged on one side of the fixing plate. The invention can test the change of the retraction rate of the separator, which helps to improve the quality of the battery. In addition, the invention also discloses a method for testing the tensile retraction rate of the lithium battery separator.

Description

A test device and test method for tensile retraction rate of lithium battery separator

technical field

The invention belongs to the technical field of battery production and manufacture, and particularly relates to a test device and a test method for the tensile shrinkage rate of a lithium battery separator.

Background technique

The main part of the lithium battery is composed of five parts: positive electrode, negative electrode, electrolyte, separator, and shell. Among them, the lithium battery separator is an important part of the lithium ion battery, which separates the positive and negative electrodes, prevents the internal short circuit of the battery, and allows the electrolyte Ions freely pass through and complete the electrochemical charging and discharging process; their performance determines the interface structure, internal resistance, etc. of the battery, which directly affects the capacity, cycle performance and safety performance of the battery. The excellent performance of the separator can improve the overall performance of the battery have an important role.

Under the premise that the thickness of the separator in the lithium battery is as thin as possible, it is necessary to ensure a certain physical and mechanical strength to meet the various environments during the production and use of the separator. In the battery production process, the separator needs to be curled together with the positive and negative electrode materials to form our common cylindrical or soft pack battery. Sufficient tensile strength can ensure that the separator does not break during the curling process and can be formed smoothly.

Due to the inconsistent tensile strength of the separator and the positive electrode or negative electrode, the tensile force is removed after the battery is wound, the separator retracts significantly, and the length of the separator does not match the positive or negative electrode, resulting in wrinkles on the positive or negative electrode. , which seriously affects the performance of lithium batteries.

SUMMARY OF THE INVENTION

One of the objectives of the present invention is to provide a test device for the tensile retraction rate of a lithium battery separator in view of the deficiencies of the prior art, which can test the change of the retraction rate of the separator and help improve the quality of the battery.

In order to achieve the above object, the present invention adopts the following technical solutions:

A testing device for the tensile retraction rate of a lithium battery diaphragm, comprising a tension machine, a crossbar and a platform are installed; a first gripper and a second gripper are respectively installed on the tension machine; the first clamp One end of the holder is connected to the cross bar, the other end of the first holder clamps the upper end of the diaphragm to be measured, one end of the second holder clamps the lower end of the diaphragm to be measured, and the first holder clamps the lower end of the diaphragm to be measured. The other ends of the two grippers are connected to the platform; a fixing plate and a reference ruler, the first gripper fixes the upper end of the fixing plate, and the fixing plate is located on the two first grippers and the second Between the two holders, the reference ruler is arranged on one side of the fixing plate.

Preferably, it also includes two uprights, the uprights are vertically installed on the platform, the crossbar is installed between the two uprights, and the crossbar is parallel to the platform.

Preferably, a control panel is also included, and both the first holder and the second holder are connected to the control panel.

Preferably, it also includes a host computer, and the host computer is connected to the control panel through a data cable for communication.

Preferably, a camera is also included, and the camera is installed on the side of the upright column facing the diaphragm to be measured.

Preferably, a lift motor is installed in the upright column, and the output end of the lift motor is connected to the cross bar.

The second purpose of the present invention is to provide a test method for the tensile retraction rate of a lithium battery separator, including:

Mark the first straight line and the second straight line on the surface of the diaphragm to be tested, and set the distance between the first straight line and the second straight line;

Presetting the initial distance and initial position between the first gripper and the second gripper;

Pull the diaphragm to be tested to stretch the preset distance and keep it for a preset time, and then quickly return the first gripper to the initial position;

Record the length L0 of the diaphragm to be tested before the mark is stretched, the length L1 of the diaphragm to be tested after stretching, and the length L2 of the diaphragm to be tested after the natural retraction;

According to the retraction ratio of the separator=(L1-L2)/L1*100%, the tensile retraction ratio of the battery separator is obtained.

The third object of the present invention is to provide a test method for the tensile retraction rate of a lithium battery separator, including:

Mark the first straight line and the second straight line on the surface of the diaphragm to be tested, and set the distance between the first straight line and the second straight line;

Presetting the initial distance and initial position between the first gripper and the second gripper;

Stretch the diaphragm to be tested, increase the tension to the preset pressure, then maintain a constant tension within a preset time, and then quickly return the first gripper to the initial position;

Record the length L0 of the diaphragm to be tested before the mark is stretched, the length L1 of the diaphragm to be tested after stretching, and the length L2 of the diaphragm to be tested after the natural retraction;

According to the retraction ratio of the separator=(L1-L2)/L1*100%, the tensile retraction ratio of the battery separator is obtained.

The fourth object of the present invention is to provide a method for testing the tensile retraction rate of a lithium battery separator, including:

Mark the first straight line and the second straight line on the surface of the diaphragm to be tested, and set the distance between the first straight line and the second straight line;

Presetting the initial distance and initial position between the first gripper and the second gripper;

Align the lower end of the first gripper with the first straight line, and then clamp the diaphragm to be measured, so that the zero mark of the reference ruler is aligned with the first straight line;

Pull the diaphragm to be tested to stretch the preset distance and keep it for a preset time, and then quickly return the first gripper to the initial position;

Record the scale X0 before the diaphragm to be tested is stretched, the scale X1 after the diaphragm to be tested is stretched, and the second straight line corresponding to the scale X2 after the diaphragm to be tested is naturally retracted;

According to the retraction ratio of the separator=(X1-X2)/X1*100%, the tensile retraction ratio of the battery separator is obtained.

The fifth object of the present invention is to provide a test method for the tensile retraction rate of a lithium battery separator, including:

Mark the first straight line and the second straight line on the surface of the diaphragm to be tested, and set the distance between the first straight line and the second straight line;

Presetting the initial distance and initial position between the first gripper and the second gripper;

Align the lower end of the first gripper with the first straight line, and then clamp the diaphragm to be measured, so that the zero mark of the reference ruler is aligned with the first straight line;

Stretch the diaphragm to be tested, increase the tension to the preset pressure, then maintain a constant tension within a preset time, and then quickly return the first gripper to the initial position;

Record the scale X0 before the diaphragm to be tested is stretched, the scale X1 after the diaphragm to be tested is stretched, and the second straight line corresponding to the scale X2 after the diaphragm to be tested is naturally retracted;

According to the retraction ratio of the separator=(X1-X2)/X1*100%, the tensile retraction ratio of the battery separator is obtained.

The beneficial effect of the present invention is that the first holder of the tensile machine of the present invention simultaneously clamps the fixing plate and the upper end of the diaphragm to be measured, and the second holder clamps the lower end of the diaphragm to be measured, so that constant stretching can be performed as required The test of the diaphragm retraction rate under the condition of distance or constant tension is used to evaluate the tensile retraction performance of the diaphragm. The reference ruler is fixed on the left side of the fixed plate, and the reference ruler is used to calibrate the measurement length to ensure the accuracy of the test results. The invention can test the change of the retraction rate of the separator, which is helpful to improve the quality of the battery.

Description of drawings

Features, advantages and technical effects of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram of Embodiment 1 of the present invention.

Among them, the reference numerals are described as follows:

1- Rally machine;

2 - crossbar;

3 - Platform;

4 - the first gripper;

5-Second gripper;

6- Diaphragm to be tested;

7-Fixed plate;

8- benchmark ruler;

9-column;

10 - control panel;

20 - camera;

30 - Zero tick mark.

Detailed ways

As used in the specification and claims, certain terms are used to refer to particular components. It should be understood by those skilled in the art that hardware manufacturers may refer to the same component by different nouns. The description and claims do not use the difference in name as a way to distinguish components, but use the difference in function of the components as a criterion for distinguishing. As mentioned in the entire specification and claims, "comprising" is an open-ended term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range, and basically achieve technical effects.

Furthermore, the terms "first," "second," etc. are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In the invention, unless otherwise expressly specified and limited, the terms "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection, Or integrally connected; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

The present invention will be described in further detail below with reference to FIG. 1, but it is not intended to limit the present invention.

Embodiment 1

Embodiment 1 will be described below in conjunction with FIG. 1

The test device for the tensile and retraction rate of lithium battery separator includes a tension machine 1, which is installed with a cross bar 2 and a platform 3; a first gripper 4 and a second gripper 5, which are respectively installed on the tension machine 1; the first clamp One end of the holder 4 is connected to the cross bar 2, the other end of the first holder 4 clamps the upper end of the diaphragm 6 to be measured, and one end of the second holder 5 clamps the lower end of the diaphragm 6 to be measured. The other end of 5 is connected to the platform 3; the fixed plate 7 and the reference ruler 8, the first holder 4 is fixed on the upper end of the fixed plate 7, and the fixed plate 7 is located between the two first holders 4 and the second holder 5, The reference ruler 8 is provided on one side of the fixing plate 7 .

Due to the inconsistent tensile strength of the separator and the positive electrode or negative electrode, the tensile force is removed after the battery is wound, the separator retracts significantly, and the length of the separator does not match the positive or negative electrode, resulting in wrinkles on the positive or negative electrode. , which seriously affects the performance of the lithium battery. Therefore, during the test, the first holder 4 of the tensile machine 1 clamps the upper end of the fixed plate 7 and the diaphragm 6 to be measured at the same time, and the second holder 5 clamps the diaphragm 6 to be measured. The lower end of the diaphragm can be tested for the retraction rate of the diaphragm under the condition of constant stretching distance or constant tension according to the requirements, so as to evaluate the tensile retraction performance of the diaphragm. Calibrate the measurement length to ensure the accuracy of the test results.

In this embodiment, the first gripper 4 and the second gripper 5 are both pneumatic grippers, and the surface of the diaphragm 6 to be measured can be marked with a fixed length, which is convenient for measuring the tension of the diaphragm 6 to be measured before stretching. The length of the rear and the natural retraction of the diaphragm.

The test device for the tensile and retraction ratio of the lithium battery separator according to the present invention further includes two uprights 9, the uprights 9 are vertically installed on the platform 3, the crossbar 2 is installed between the two uprights 9, and the crossbar 2 is connected to the platform. 3 parallel. Specifically, the cross bar 2 plays the role of fixing the position of the first gripper 4 above the platform 3 , and the position of the cross bar 2 can be adjusted according to actual production requirements.

The test device for the tensile-retraction rate of the lithium battery separator according to the present invention further includes a control panel 10 , and the first holder 4 and the second holder 5 are both connected to the control panel 10 . In some embodiments, the first gripper 4 and the second gripper 5 are controlled by a control panel 10, and the control panel 10 may have a built-in communication module, which facilitates remote monitoring of the testing device and helps improve user experience.

The device for testing the tensile and retraction ratio of the lithium battery separator according to the present invention further includes an upper computer, and the upper computer is connected to the control panel 10 for communication through a data cable. Specifically, the tension machine 1 is connected to the upper computer through a data cable, and the upper computer controls the tension machine 1 to stretch the diaphragm 6 to be tested through the control panel 10. After the stretching is completed, the first gripper 4 and the second gripper 5 return to At the initial position, the diaphragm retracts naturally, and the upper computer is a computer.

The device for testing the tensile-retraction rate of the lithium battery separator according to the present invention further includes a camera 20, and the camera 20 is installed on the side of the column 9 facing the separator 6 to be tested. In this embodiment, the camera 20 is fixed on the left column 9 of the tensile machine 1. The camera 20 monitors the change of the diaphragm length after the tensile force is removed in real time, and can accurately measure the change of the diaphragm retraction rate with retraction time.

In the test device for the tensile and retraction ratio of the lithium battery separator according to the present invention, a lift motor is installed in the upright column 9 , and the output end of the lift motor is connected to the cross bar 2 . In this embodiment, the lift motor can drive the cross bar 2 to ascend or descend, that is, to drive the first gripper 4 to ascend or descend. The lift motor can be a stepper motor or a servo motor.

The working principle of the present invention is:

During the test, the first clamp 4 of the tension machine 1 clamps the upper end of the fixed plate 7 and the diaphragm 6 to be tested at the same time, and the second clamp 5 clamps the lower end of the diaphragm 6 to be tested, which can perform constant stretching as required The test of the diaphragm retraction rate under the condition of distance or constant tension, so as to evaluate the tensile retraction performance of the diaphragm, wherein the reference ruler 8 is fixed on the left side of the fixing plate 7, and the reference ruler 8 is used to calibrate the measurement length to ensure the accuracy of the test results. .

Embodiment 2

A test method for the tensile retraction rate of a lithium battery separator, comprising:

Mark the first straight line and the second straight line on the surface of the diaphragm 6 to be tested, and set the distance between the first straight line and the second straight line;

Preset the initial distance and initial position between the first gripper 4 and the second gripper 5;

Pull the diaphragm 6 to be tested to stretch the preset distance and keep it for a preset time, and then quickly return the first gripper 4 to the initial position;

Record the length L0 of the diaphragm 6 to be measured before the mark is stretched, the length L1 of the diaphragm 6 to be measured after stretching, and the length L2 of the diaphragm 6 to be measured after the natural retraction;

According to the retraction ratio of the separator=(L1-L2)/L1*100%, the tensile retraction ratio of the battery separator is obtained.

It should be noted that: mark the first straight line A and the second straight line B on the surface of the diaphragm to be measured, the distance between AB and AB is L, and then set the distance between the first holder 4 and the second holder 5 as d; The steps of setting the tension machine stretching program in the computer are as follows: the first gripper 4 pulls the diaphragm 6 to be tested for a distance of ΔL and maintains the time t1, and then the gripper quickly returns to the initial position; in addition, it can be preset. Fix the interval shooting time of the camera 20, run the tension machine 1 and the camera 20 at the same time, and record the diaphragm before stretching (T=0), after stretching (T=t1) and after the diaphragm naturally retracts t2 (T=t1) +t2) image; in the computer, the length of the reference ruler in the above image can be established as a length measurement ruler, and then based on the established ruler, measure the surface of the diaphragm before stretching (T=0) and after stretching (T=t1). ) and the length of the diaphragm after the natural retraction of t2 (T=t1+t2), respectively denoted as L0, L1, and L2.

Embodiment 3

A test method for the tensile retraction rate of a lithium battery separator, comprising:

Mark the first straight line and the second straight line on the surface of the diaphragm 6 to be tested, and set the distance between the first straight line and the second straight line;

Preset the initial distance and initial position between the first gripper 4 and the second gripper 5;

Stretch the diaphragm 6 to be tested, increase the tension to the preset pressure, and then maintain a constant tension within a preset time, and then quickly return the first gripper 4 to the initial position;

Record the length L0 of the diaphragm 6 to be measured before the mark is stretched, the length L1 of the diaphragm 6 to be measured after stretching, and the length L2 of the diaphragm 6 to be measured after the natural retraction;

According to the retraction ratio of the separator=(L1-L2)/L1*100%, the tensile retraction ratio of the battery separator is obtained.

It should be noted that: mark the first straight line A and the second straight line B on the surface of the diaphragm to be measured, the distance between AB and AB is L, and then set the distance between the first holder 4 and the second holder 5 as d; The steps of setting the tension machine stretching program in the computer are: the first gripper 4 stretches the diaphragm 6 to be tested, the tension increases to F, and then the constant tension time is t1, and then the gripper quickly returns to the initial position, in addition , you can preset the interval shooting time of the camera 20, run the tension machine 1 and the camera 20 at the same time, and record the diaphragm before stretching (T=0), after stretching (T=t1) and the diaphragm naturally retracting t2. The image after (T=t1+t2); in the computer, the length of the reference ruler in the above image can be established as a length measurement ruler, and then based on the established ruler, the surface of the diaphragm is measured. Mark before stretching (T=0), stretching The lengths after (T=t1) and after the diaphragm naturally retracts t2 (T=t1+t2) are recorded as L0, L1, and L2, respectively.

Embodiment 4

A test method for the tensile retraction rate of a lithium battery separator, comprising:

Mark the first straight line and the second straight line on the surface of the diaphragm 6 to be tested, and set the distance between the first straight line and the second straight line;

Preset the initial distance and initial position between the first gripper 4 and the second gripper 5;

The lower end of the first holder 4 is coincident with the first straight line, and the diaphragm 6 to be measured is clamped, so that the zero mark 30 of the reference ruler 8 is aligned with the first straight line A;

Pull the diaphragm 6 to be tested to stretch the preset distance and keep it for a preset time, and then quickly return the first gripper 4 to the initial position;

Record the scale X0 before the diaphragm 6 to be measured is stretched, the scale X1 after the diaphragm 6 to be measured is stretched, and the second straight line B corresponding to the scale X2 after the diaphragm 6 to be measured is naturally retracted;

According to the retraction ratio of the separator=(X1-X2)/X1*100%, the tensile retraction ratio of the battery separator is obtained.

It should be noted that: mark the first straight line A and the second straight line B on the surface of the diaphragm to be measured, the distance between AB and AB is L, and then set the distance between the first holder 4 and the second holder 5 as d; The steps of setting the tension machine stretching program in the computer are as follows: the first gripper 4 pulls the diaphragm 6 to be tested for a distance of ΔL and maintains the time t1, and then the gripper quickly returns to the initial position; in addition, it can be preset. Fix the interval shooting time of the camera 20, run the tension machine 1 and the camera 20 at the same time, and record the diaphragm before stretching (T=0), after stretching (T=t1) and after the diaphragm naturally retracts t2 (T=t1) +t2) The image at the second straight line B; read in the image processing software before stretching (T=0), after stretching (T=t1) and after natural retraction of the diaphragm t2 (T=t1+t2) The second straight line B corresponding to the scale is marked as X0, X1 and X2 respectively.

Embodiment 5

Mark the first straight line and the second straight line on the surface of the diaphragm 6 to be tested, and set the distance between the first straight line and the second straight line;

Preset the initial distance and initial position between the first gripper 4 and the second gripper 5;

The lower end of the first holder 4 is coincident with the first straight line, and the diaphragm 6 to be measured is clamped, so that the zero mark 30 of the reference ruler 8 is aligned with the first straight line A;

Stretch the diaphragm 6 to be tested, increase the tension to the preset pressure, and then maintain a constant tension within a preset time, and then quickly return the first gripper 4 to the initial position;

Record the scale X0 before the diaphragm 6 to be measured is stretched, the scale X1 after the diaphragm 6 to be measured is stretched, and the second straight line B corresponding to the scale X2 after the diaphragm 6 to be measured is naturally retracted;

According to the retraction ratio of the separator=(X1-X2)/X1*100%, the tensile retraction ratio of the battery separator is obtained.

It should be noted that: mark the first straight line A and the second straight line B on the surface of the diaphragm to be measured, the distance between AB and AB is L, and then set the distance between the first holder 4 and the second holder 5 as d; The steps of setting the tension machine stretching program in the computer are: the first gripper 4 stretches the diaphragm 6 to be tested, the tension increases to F, and then the constant tension time is t1, and then the gripper quickly returns to the initial position, in addition , you can preset the interval shooting time of the camera 20, run the tension machine 1 and the camera 20 at the same time, and record the diaphragm before stretching (T=0), after stretching (T=t1) and the diaphragm naturally retracting t2. The image at the second straight line B after (T=t1+t2); read in the image processing software before stretching (T=0), after stretching (T=t1) and after natural retraction of the diaphragm t2 (T = t1+t2), the second straight line B corresponds to the scale, which are respectively denoted as X0, X1, and X2.

Based on the disclosure and teaching of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above-described embodiments. Therefore, the present invention is not limited to the above-mentioned specific embodiments, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention falls within the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims (10)

1. The utility model provides a testing arrangement of tensile retractility of lithium cell diaphragm which characterized in that includes:

the tensile machine (1) is provided with a cross rod (2) and a platform (3);

the first gripper (4) and the second gripper (5) are respectively arranged on the tensile machine (1);

one end of the first clamp holder (4) is connected with the cross rod (2), the other end of the first clamp holder (4) clamps the upper end of a diaphragm (6) to be tested, one end of the second clamp holder (5) clamps the lower end of the diaphragm (6) to be tested, and the other end of the second clamp holder (5) is connected with the platform (3);

fixed plate (7) and reference scale (8), first holder (4) are fixed plate (7) upper end, fixed plate (7) are located two first holder (4) with between second holder (5), reference scale (8) set up one side of fixed plate (7).

2. The device for testing the tensile shrinkage of the lithium battery diaphragm as claimed in claim 1, wherein: the platform is characterized by further comprising two stand columns (9), wherein the stand columns (9) are vertically arranged on the platform (3), the cross rod (2) is arranged between the two stand columns (9), and the cross rod (2) is parallel to the platform (3).

3. The device for testing the tensile shrinkage of the lithium battery diaphragm as set forth in claim 1, wherein: the clamping device further comprises a control panel (10), and the first clamp (4) and the second clamp (5) are connected to the control panel (10).

4. The device for testing the tensile shrinkage of the lithium battery diaphragm as claimed in claim 3, wherein: the device is characterized by further comprising an upper computer, wherein the upper computer is in communication connection with the control panel (10) through a data line.

5. The device for testing the tensile shrinkage of the lithium battery diaphragm as claimed in claim 2, wherein: the device is characterized by further comprising a camera (20), wherein the camera (20) is installed on one surface, facing the diaphragm (6) to be measured, of the stand column (9).

6. The device for testing the tensile shrinkage of the lithium battery diaphragm as claimed in claim 2, wherein: and a lifting motor is arranged in the upright post (9), and the output end of the lifting motor is connected with the cross rod (2).

7. A test method for tensile shrinkage of a lithium battery diaphragm is characterized by comprising the following steps:

marking a first straight line and a second straight line on the surface of the diaphragm (6) to be measured, and setting the distance between the first straight line and the second straight line;

presetting an initial distance and an initial position between a first clamp (4) and a second clamp (5);

drawing the diaphragm (6) to be measured to stretch for a preset distance and keeping for a preset time, and then quickly returning the first clamp (4) to the initial position;

recording the length L0 of the mark of the diaphragm (6) to be tested before stretching, the length L1 of the diaphragm (6) to be tested after stretching and the length L2 of the diaphragm (6) to be tested after natural retraction;

the battery separator stretch recovery was obtained from the separator recovery rate (L1-L2)/L1 × 100%.

8. A test method for tensile shrinkage of a lithium battery diaphragm is characterized by comprising the following steps:

marking a first straight line and a second straight line on the surface of the diaphragm (6) to be measured, and setting the distance between the first straight line and the second straight line;

presetting an initial distance and an initial position between a first clamp (4) and a second clamp (5);

stretching the diaphragm (6) to be tested, increasing the tension to a preset pressure, then keeping constant tension within a preset time, and then quickly returning the first clamp (4) to the initial position;

recording the length L0 of the mark of the diaphragm (6) to be tested before stretching, the length L1 of the diaphragm (6) to be tested after stretching and the length L2 of the diaphragm (6) to be tested after natural retraction;

the battery separator stretch recovery was obtained from the separator recovery rate (L1-L2)/L1 × 100%.

9. A test method for tensile shrinkage of a lithium battery diaphragm is characterized by comprising the following steps:

marking a first straight line and a second straight line on the surface of the diaphragm (6) to be measured, and setting the distance between the first straight line and the second straight line;

presetting an initial distance and an initial position between a first clamp (4) and a second clamp (5);

the lower end of the first clamp holder (4) is overlapped with the first straight line, and then the diaphragm (6) to be measured is clamped, so that a zero scribed line of the reference ruler (8) is aligned with the first straight line;

drawing the diaphragm (6) to be measured to stretch for a preset distance and keeping for a preset time, and then quickly returning the first clamp (4) to the initial position;

recording a scale X0 before the membrane (6) to be tested is stretched, a scale X1 after the membrane (6) to be tested is stretched, and a scale X2 corresponding to a second straight line after the membrane (6) to be tested is naturally retracted;

the battery separator stretch recovery was obtained from the separator recovery rate (X1-X2)/X1 × 100%.

10. A test method for tensile shrinkage of a lithium battery diaphragm is characterized by comprising the following steps:

marking a first straight line and a second straight line on the surface of the diaphragm (6) to be measured, and setting the distance between the first straight line and the second straight line;

presetting an initial distance and an initial position between a first clamp (4) and a second clamp (5);

the lower end of the first clamp holder (4) is overlapped with the first straight line, and then the diaphragm (6) to be measured is clamped, so that a zero scribed line of the reference ruler (8) is aligned with the first straight line;

stretching the diaphragm (6) to be tested, increasing the tension to a preset pressure, then keeping constant tension within a preset time, and then quickly returning the first clamp (4) to the initial position;

recording a scale X0 before the membrane (6) to be tested is stretched, a scale X1 after the membrane (6) to be tested is stretched, and a scale X2 corresponding to a second straight line after the membrane (6) to be tested is naturally retracted;

the battery separator stretch recovery was obtained from the separator recovery rate (X1-X2)/X1 × 100%.

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