阅读说明：本技术 批量测试锂电池隔膜热闭孔温度和破膜温度的方法 (Method for testing thermal closed hole temperature and film breaking temperature of lithium battery diaphragm in batch ) 是由 程跃 匡吴奇 庄志 鲍晋珍 于 2019-11-27 设计创作，主要内容包括：本发明涉及一种批量测试锂电池隔膜热闭孔温度和破膜温度的测试方法,其特征在于,本测试的模具包含CR2016纽扣电池,T型热电偶,聚四氟乙烯螺母；上螺丝接线柱及下螺丝接线柱通过电焊连接在上螺丝和下螺丝的螺帽上,上螺丝和下螺丝通过螺纹旋进聚四氟乙烯螺母中,聚四氟乙烯螺母中心处开有小孔,将T型热电偶穿过小孔,固定在下螺丝的凹槽中,CR2016纽扣电池的负极面朝下螺丝侧放置于聚四氟乙烯螺母中,在聚四氟乙烯螺母中放置弹簧,使其与纽扣电池呈现自由接触状态。本申请通过将多个测试模具连接在多通道数据采集仪上,大批量、快速、准确测试隔膜的热闭孔温度和破膜温度,能够有效指导隔膜产品的开发和生产。(The invention relates to a test method for batch testing of the thermal closed hole temperature and the film breaking temperature of lithium battery diaphragms, which is characterized in that a test die comprises a CR2016 button battery, a T-shaped thermocouple and a polytetrafluoroethylene nut; go up screw terminal and screw terminal down and pass through the electric welding and connect on the nut of last screw and screw down, go up the screw and screw precession polytetrafluoroethylene nut down through the screw thread, polytetrafluoroethylene nut center department opens has the aperture, passes the aperture with T type thermocouple, fixes in the recess of screw down, and CR2016 button cell's negative pole face down screw side is placed in polytetrafluoroethylene nut, places the spring in polytetrafluoroethylene nut, makes it and button cell present free contact state. This application is through connecting a plurality of test mould on multichannel data acquisition appearance, and the development and the production of diaphragm product can effectively be instructed to the hot hole temperature of closing and the rupture of membranes temperature of big batch, quick, accurate test diaphragm.)

1. A method for testing the thermal closed pore temperature and the film breaking temperature of lithium battery diaphragms in batches is characterized by comprising the following specific steps,

1) firstly, the testing method needs to use a die cutting machine to cut the diaphragm into a circular sample wafer with the thickness of 15.8mm, and the sample wafer is soaked in 10mL of electrolyte for 2h so that the diaphragm can be fully soaked;

2) assembling the diaphragm sample wafer according to the assembling sequence of the positive electrode shell, the stainless steel gasket, the diaphragm, the stainless steel gasket, the elastic sheet and the negative electrode shell, and packaging the diaphragm sample wafer into a CR2016 type button battery by a button battery sealing machine, wherein the packaging pressure is 1000 PSI;

3) placing the packaged button battery with the negative electrode surface facing downwards and the side of the screw in a testing mold, placing the spring on the button battery, screwing the upper screw into the testing mold, and ensuring the stable connection of the whole testing mold;

4) simultaneously assembling 5 batches of test dies, and respectively connecting an upper screw binding post, a lower screw binding post and a thermocouple of the test dies to a resistance acquisition module connecting line and a temperature acquisition module connecting line of a multi-channel data acquisition instrument so as to acquire internal resistance and temperature data of the diaphragm;

5) putting the whole test mould into an oven for heating, and simultaneously, starting to record resistance and temperature data of the diaphragm by a multi-channel data acquisition instrument;

6) when the temperature of the diaphragm reaches 180 ℃, stopping heating the oven, and moving out the test mold;

7) making a curve of the resistance data and the temperature data of the diaphragm, deriving the curve, and taking the maximum value of the derivative of the whole curve as the thermal closed hole temperature of the diaphragm, wherein the value means the point at which the resistance value of the diaphragm increases fastest along with the temperature, namely the temperature at which the diaphragm starts to close the hole; and taking the minimum value of the derivative of the whole curve as the rupture temperature of the diaphragm.

2. A test device for batch test of the thermal closed hole temperature and the film breaking temperature of a lithium battery diaphragm is characterized in that a test die comprises a CR2016 button battery, a T-shaped thermocouple and a polytetrafluoroethylene nut; go up screw terminal and screw terminal down and pass through the electric welding and connect on the nut of last screw and screw down, go up the screw and screw precession polytetrafluoroethylene nut down through the screw thread, polytetrafluoroethylene nut center department opens has the aperture, passes the aperture with T type thermocouple, fixes in the recess of screw down, and CR2016 button cell's negative pole face down screw side is placed in polytetrafluoroethylene nut, places the spring in polytetrafluoroethylene nut, makes it and button cell present free contact state.

3. The apparatus as claimed in claim 2, wherein the CR2016 button cell is packaged by assembling a sample piece of the membrane in the order of positive casing, stainless steel gasket, membrane, stainless steel gasket, spring plate, and negative casing, and then packaging the sample piece of the membrane into the CR2016 button cell with a sealing pressure of 1000PSI by a button cell sealing machine.

4. The apparatus as claimed in claim 2, wherein the T-type thermocouple has a temperature measuring range of 0-350 ℃ and a temperature accuracy of 0.5 ℃.

5. The apparatus for batch testing of thermal shutdown temperature and rupture temperature of lithium battery separator as claimed in claim 2, wherein a plurality of said test dies are connected in parallel to a test device for batch testing of thermal shutdown temperature and rupture temperature of separator.

6. The apparatus for batch testing of thermal shutdown temperature and rupture temperature of lithium battery separator as claimed in claim 2, wherein 5 said test dies are connected in parallel to the test equipment.

7. The device for batch testing of the thermal shutdown temperature and the rupture temperature of the lithium battery diaphragm as claimed in claim 6, wherein the testing equipment comprises five testing dies, a conducting wire, a temperature data acquisition module, a resistance data acquisition module, a multi-channel data acquisition instrument; the upper and lower screw binding posts of the 5 testing dies are respectively connected to the resistance data testing module through leads, the thermocouples of the dies are connected to the temperature data testing module through leads, and the resistance data acquisition module and the temperature data acquisition module are welded on the multi-channel data acquisition instrument.

Technical Field

The invention relates to the technical field of diaphragm test equipment, in particular to a method for testing the thermal closed pore temperature and the rupture temperature of lithium battery diaphragms in batches.

Background

With the development of science and technology, lithium ion batteries have been widely applied to 3C electronic devices and power automobiles, which rapidly drives the production of diaphragms, which are important constituent materials of lithium ion batteries. However, in recent years, the safety accidents of the lithium battery frequently occur, which causes a great amount of property loss and even threatens the personal safety, so that the improvement of the safety performance of the lithium battery in all aspects is not slow to the development of the whole industry, and the diaphragm serving as one of four core materials in the lithium battery is of great importance to the safety performance of the lithium battery.

As is well known, the separator has the function of separating the positive electrode and the negative electrode of the battery to prevent the contact between the positive electrode and the negative electrode from causing safety problems, and the microporous structure of the separator can allow electrolyte ions to pass through. The performance of the battery directly determines the interface structure, internal resistance and heat resistance of the battery, and further directly influences the electrical performance and safety performance of the battery. When the diaphragm reaches a certain temperature, the internal micropores of the diaphragm are closed to a certain degree, so that the flow channel of lithium ions is cut off, the temperature of the battery is prevented from rising continuously, and the safety of the lithium ion battery is guaranteed; if the temperature continues to rise, the membrane can be fused, so that the whole membrane is broken, the action of isolating the positive electrode and the negative electrode disappears, and the lithium ion battery is easy to lose control. Therefore, the two critical temperatures have very important influence on the safety performance of the lithium ion battery, and how to test the thermal closed pore temperature and the membrane breaking temperature of the diaphragm quickly, accurately and in batch is a continuously pursued target in the whole industry.

At present, the thermal pore-closing temperature and the rupture temperature of the diaphragm also have partial testing methods, including a method for testing the change of the internal resistance value of the diaphragm along with the temperature and a method for testing the change of the gas throughput of the diaphragm along with the temperature, however, the methods are all faced with a method with single testing times, if the diaphragm is simultaneously tested in a large batch, additional testing equipment is required, and the cost is increased. In order to solve the difficulty of quickly, accurately and massively testing the thermal closed pore temperature of the diaphragm of the lithium ion battery required in the diaphragm industry, the invention develops a testing device for testing the thermal closed pore temperature and the rupture temperature of the diaphragm of the lithium ion battery in batches.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for testing the thermal closed pore temperature and the rupture temperature of a lithium battery diaphragm in batches.

The purpose of the invention is realized by the following technical scheme:

a method for testing the thermal closed hole temperature and the film breaking temperature of lithium battery diaphragms in batches comprises the following specific steps:

1) firstly, the testing method needs to use a die cutting machine to cut the diaphragm into a circular sample wafer with the thickness of 15.8mm, and the sample wafer is soaked in 10mL of electrolyte for 2h so that the diaphragm can be fully soaked;

2) assembling the diaphragm sample wafer according to the assembling sequence of the positive electrode shell, the stainless steel gasket, the diaphragm, the stainless steel gasket, the elastic sheet and the negative electrode shell, and packaging the diaphragm sample wafer into a CR2016 type button battery by a button battery sealing machine, wherein the packaging pressure is 1000 PSI;

3) placing the packaged button battery with the negative electrode surface facing downwards into a testing mold, placing a spring on the button battery, screwing the upper screw into the testing mold, enabling the spring to apply a certain pressure to the battery, and ensuring the stable connection of the whole testing mold;

4) simultaneously assembling 5 batches of test moulds, and respectively connecting an upper screw wiring terminal, a lower screw wiring terminal and a thermocouple of the test moulds to a resistance acquisition module connecting line and a temperature acquisition module connecting line of a multi-channel data acquisition instrument so as to acquire internal resistance and temperature data of the diaphragm;

5) putting the whole test mould into an oven for heating, and simultaneously, starting to record resistance and temperature data of the diaphragm by a multi-channel data acquisition instrument;

6) with the temperature rise, the resistance value of the diaphragm can also show the condition of increasing firstly and then reducing, when the temperature of the diaphragm reaches 180 ℃, the oven stops heating, and the test mould is moved out;

7) making a curve of the resistance data and the temperature data of the diaphragm, deriving the curve, and taking the maximum value of the derivative of the whole curve as the hot closed hole temperature of the diaphragm, wherein the value means the point at which the resistance value of the diaphragm is increased fastest along with the temperature, namely the temperature at which the diaphragm starts to close the hole; and taking the minimum value of the derivative of the whole curve as the membrane breaking temperature of the membrane, wherein the meaning of the value is the point at which the resistance of the membrane is reduced fastest along with the temperature, namely the temperature at which the membrane starts to break.

A test device for batch testing of the thermal closed hole temperature and the membrane rupture temperature of a lithium battery diaphragm comprises a CR2016 button battery, a T-shaped thermocouple and a polytetrafluoroethylene nut; the upper screw wiring terminal and the lower screw wiring terminal are connected to nuts of the upper screw and the lower screw through electric welding, the upper screw and the lower screw are screwed into the polytetrafluoroethylene nut through threads, a small hole is formed in the center of the polytetrafluoroethylene nut, the T-shaped thermocouple penetrates through the small hole and is fixed in a groove of the lower screw, the negative electrode surface of the CR2016 button battery faces downwards, the screw is placed in the polytetrafluoroethylene nut, and the spring is placed in the polytetrafluoroethylene nut to enable the CR button battery and the button battery to be in a free contact state.

The button cell needs to be packaged, the diaphragm sample is assembled according to the assembly sequence of the positive electrode shell, the stainless steel gasket, the diaphragm, the stainless steel gasket, the elastic sheet and the negative electrode shell, the diaphragm sample is packaged into a CR2016 type button cell through a button cell sealing machine, and the packaging pressure of the button cell is 1000 PSI.

The temperature measuring range of the T-shaped thermocouple is 0-350 ℃, and the temperature precision is 0.5 ℃.

And connecting a plurality of test dies on test equipment in parallel, and testing the thermal closed hole temperature and the rupture temperature of the diaphragm in batches.

And 5 test dies are connected in parallel on the test equipment.

The test equipment comprises five test dies, a lead, a temperature data acquisition module, a resistance data acquisition module and a multi-channel data acquisition instrument; the upper and lower screw binding posts of the 5 testing dies are respectively connected to the resistance data testing module through leads, the thermocouples of the dies are connected to the temperature data testing module through leads, and the resistance data acquisition module and the temperature data acquisition module are welded on the multi-channel data acquisition instrument.

Compared with the prior art, the invention has the following positive effects:

by designing a convenient and practical test die, the packaged button cell is placed in the die, and the obtained data is accurate, stable and reliable; and a plurality of testing dies can be connected on the multi-channel data acquisition instrument to test the hot closed hole temperature and the film breaking temperature of the diaphragm in batches, so that the testing efficiency of the hot closed hole temperature and the film breaking temperature of the diaphragm is greatly improved.

Drawings

FIG. 1a is a block diagram of a test fixture of the present application;

FIG. 1b is a top view of an upper screw in the test fixture of the present application;

FIG. 1c is a top view of a Teflon nut in the test fixture of the present application;

FIG. 1d is a top view of the lower screw and the lower screw groove in the test fixture of the present application;

FIG. 2 is a connection diagram of the test equipment of the present application;

FIG. 3 is a process flow diagram of the present application;

the labels in the figures are:

1, a screw binding post is arranged on the screw,

2, the screw is arranged on the screw rod,

3, a polytetrafluoroethylene nut is arranged on the outer side of the nut,

4, a spring is arranged in the groove,

a 5CR2016 type button cell battery,

a type 6T thermocouple is arranged on the base,

7 a lower screw is arranged on the lower part of the screw,

8, a lower screw wiring terminal is arranged on the lower screw,

9 the top view of the upper screw is that,

10 the polytetrafluoroethylene nut is shown in a top view,

11 the top view of the groove of the lower screw,

12 a top view of the lower screw of the screw,

13 a first test mould to be tested,

14 a second test mould to be tested,

15 a third test mould to be used in the method,

16 a first conductive line of a first type,

17 a fourth test mould to be used in the method,

18 a fifth one of the test dies is,

19 a second conducting line (S) of a second conducting line,

20 a temperature data acquisition module for acquiring temperature data,

21 a resistance data acquisition module for the resistance data acquisition module,

22 multichannel data acquisition instrument.

Detailed Description

The following provides a specific embodiment of a test device for batch testing of the thermal closed pore temperature and the membrane rupture temperature of the lithium battery diaphragm.

Example 1

Referring to the attached drawings 1 and 2, a test device for batch test of the thermal closed hole temperature and the membrane rupture temperature of a lithium battery diaphragm comprises a CR2016 button battery 5, a T-shaped thermocouple 6 and a polytetrafluoroethylene nut 3; the upper screw terminal 1 and the lower screw terminal 8 are connected to nuts of the upper screw 2 and the lower screw 7 through electric welding, the upper screw 2 and the lower screw 7 are screwed into the polytetrafluoroethylene nut 3 through threads, a small hole 3 is formed in the center of the polytetrafluoroethylene nut, the T-shaped thermocouple 6 penetrates through the small hole and is fixed in a groove 11 of the lower screw, the negative electrode surface of the CR2016 button cell 5 is placed in the polytetrafluoroethylene nut towards the lower screw side, and the spring 4 is placed in the polytetrafluoroethylene nut to enable the CR2016 button cell to be in a free contact state; reference numeral 9 is a top view of the upper screw, 10 is a top view of the teflon nut, and 12 is a top view of the lower screw.

The button cell 5 needs to be packaged, the diaphragm sample wafer is assembled according to the assembly sequence of the positive electrode shell, the stainless steel gasket, the diaphragm, the stainless steel gasket, the elastic sheet and the negative electrode shell, the diaphragm is packaged into a CR2016 type button cell through a button cell sealing machine, and the packaging pressure of the button cell is 1000 PSI.

The temperature measuring range of the T-shaped thermocouple 6 is 0-350 ℃, and the temperature precision is 0.5 ℃.

And connecting 5 test dies on the test equipment in parallel, and testing the hot closed hole temperature and the membrane rupture temperature of the diaphragm in batches.

The test equipment comprises a first test die 13, a second test die 14, a third test die 15, a fourth test die 17, a fifth test die 18, a first lead 16, a second lead 19, a temperature data acquisition module 20, a resistance data acquisition module 21 and a multi-channel data acquisition instrument 22; the upper and lower screw terminals of the first testing mold 13, the second testing mold 14, the third testing mold 15, the fourth testing mold 17 and the fifth testing mold 18 are connected to the resistance data testing module 17 through the first lead 16, the thermocouple of the mold is connected to the temperature data acquisition module 21 through the second lead 19, and the resistance data acquisition module 20 and the temperature data acquisition module 21 are welded on the multi-channel data acquisition instrument 22.

The flow chart of the test method of the application is shown in FIG. 3:

the test method comprises the following specific steps:

1) firstly, the testing method needs to use a die cutter to cut the diaphragm into a circular sample piece with the thickness of 15.8mm, and soak the sample piece in 10mL of electrolyte for 2h to enable the diaphragm to be fully soaked.

2) And then assembling the diaphragm sample wafer according to the assembling sequence of the positive electrode shell, the stainless steel gasket, the diaphragm, the stainless steel gasket, the elastic sheet and the negative electrode shell, and packaging the diaphragm sample wafer into the CR2016 type button battery by using a button battery sealing machine, wherein the packaging pressure is 1000 PSI.

3) And placing the packaged button battery with the negative electrode surface facing downwards into a testing mold, placing a spring on the button battery, screwing the upper screw into the testing mold, enabling the spring to apply certain pressure to the battery, and ensuring the stable connection of the whole testing mold.

4) And simultaneously assembling 5 batches of test dies, and respectively connecting an upper screw wiring terminal, a lower screw wiring terminal and a thermocouple of the test dies to a resistance acquisition module connecting line and a temperature acquisition module connecting line of the multichannel data acquisition instrument so as to acquire internal resistance and temperature data of the diaphragm.

5) And (3) putting the whole testing mold into an oven for heating, and simultaneously, starting to record the resistance and temperature data of the diaphragm by the multi-channel data acquisition instrument.

6) And when the temperature of the diaphragm reaches 180 ℃, the oven stops heating, and the test mold is removed.

7) Making a curve of the resistance data and the temperature data of the diaphragm, deriving the curve, and taking the maximum value of the derivative of the whole curve as the hot closed hole temperature of the diaphragm, wherein the value means the point at which the resistance value of the diaphragm is increased fastest along with the temperature, namely the temperature at which the diaphragm starts to close the hole; and taking the minimum value of the derivative of the whole curve as the membrane breaking temperature of the membrane, wherein the meaning of the value is the point at which the resistance of the membrane is reduced fastest along with the temperature, namely the temperature at which the membrane starts to break.

The test method takes five groups of data as a reliability judgment basis, if the temperature range of the five groups of data tested at the same time is within 1 ℃, the test result data can be considered to be reliable, and the average value of the five groups of test data is taken as the diaphragm thermal-closing hole temperature and the diaphragm rupture temperature.

Table 1: the hot closed pore temperature and the rupture temperature of a certain polyethylene-based wet diaphragm and a ceramic coating film are obtained by one-time measurement through the test method;

TABLE 1

According to the testing method, the temperature range of the testing data is basically within 1 ℃ in the same test, and the standard deviation 3 delta value of the diaphragm closed pore temperature and the diaphragm rupture temperature is within 1, so that the testing method is accurate, stable and reliable.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and decorations can be made without departing from the concept of the present invention, and these modifications and decorations should also be regarded as being within the protection scope of the present invention.