A lithium battery separator film breakage temperature measurement system and its usage method

Abstract

The present invention discloses a lithium battery separator film breakage temperature measurement system and a usage method. The system includes: a heating device, a puncturing device, a separator film, a measuring device, and a control and data acquisition and processing device. The heating device, the puncturing device, the measuring device, and the control and data acquisition and processing device are interconnected through electrical signals. The present invention can achieve monitoring of the dynamic temperature, measuring the relationship between the puncturing strength of the separator film and the temperature change, and accurately reflecting the breakage temperature of the separator film through the change in the puncturing strength, thereby improving the accuracy of measuring the breakage temperature of the separator film.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery separators, and particularly relates to a system for measuring the membrane breakage temperature of a lithium battery separator. Background Art

[0002] The main function of a lithium battery separator is to separate the positive and negative electrodes to prevent the direct contact between the positive and negative electrodes from causing battery short circuit. At the same time, it allows ions in the electrolyte to freely shuttle between the positive and negative electrodes. When the battery is in use and its local temperature rises due to short circuit, and the temperature rises close to the melting point of the separator, the micropores in the separator are self-closed, the battery internal resistance increases, and the current decreases, which plays a certain protective role for the battery. The temperature at this time is called the separator closing temperature. However, if the heating rate is very fast, resulting in the melting and rupture of the separator, the temperature at this time is called the separator breakage temperature. If the separator ruptures prematurely, causing the direct contact between the positive and negative electrodes, it will trigger safety accidents such as battery combustion and explosion. Therefore, for lithium batteries pursuing high safety performance, the greater the difference between the breakage temperature and the closing temperature of the separator, the better.

[0003] Currently, on the market, the breakage temperature of the separator is mainly measured by soaking the separator in the electrolyte and raising the temperature, and observing the change in the internal resistance of the separator. However, the electrolyte is prone to decomposition when exposed to air and at high temperatures, resulting in deviation in the measured value. Summary of the Invention

[0004] In view of the above technical defects, the present invention provides a system for measuring the membrane breakage temperature of a lithium battery separator and its usage method. This system can accurately measure the membrane breakage temperature of the separator, evaluate the safety performance of the separator, and thus enhance the market competitiveness.

[0005] To solve the above technical problems, the present invention provides a system for measuring the membrane breakage temperature of a lithium battery separator, which mainly includes: a heating device, a puncturing device, a separator, a measuring device, and a control and data acquisition and processing device. The puncturing device consists of a separator clamp and a puncturing needle. The separator clamp is located inside the heating device. The separator is clamped inside the separator clamp. The puncturing needle is fixed above the separator clamp and is located inside the heating device. The top is connected to the measuring device and the control and data acquisition and processing device through an electrical signal. The measuring device consists of a temperature detection device and a puncturing strength detection device. The temperature detection device is located inside the heating device. The puncturing strength detection device is used to measure the puncturing strength of the separator as the puncturing needle descends. The control and data acquisition and processing device consists of a control module and a data acquisition and processing module. The control module can control and adjust the temperature of the heating device and control the movement of the puncturing needle. The heating device and the puncturing device are connected to the control module through an electrical signal, and the measuring device is connected to the data acquisition and processing module through an electrical signal.

[0006] As a preferred solution of the present invention, the heating device is one of an oven and an electric furnace.

[0007] As a preferred embodiment of the present invention, the heating rate of the oven or heating furnace is 0.2 - 10 °C / min.

[0008] As a preferred embodiment of the present invention, the diaphragm clamp consists of two parts: an upper diaphragm clamp and a lower diaphragm clamp, and the shape of the diaphragm clamp is a cuboid or a cylinder.

[0009] As a preferred embodiment of the present invention, there are at least two cylindrical pinholes with the same shape in the diaphragm clamp, and the diameter of the cylindrical pinhole is 10 - 20 mm.

[0010] As a preferred embodiment of the present invention, the surface of the puncture needle is smooth and burr-free, with a diameter of 0.5 - 1.0 mm and a descending speed of 50 - 500 mm / min.

[0011] As a preferred embodiment of the present invention, the temperature detection device is a thermocouple temperature sensor or an infrared temperature sensor.

[0012] As described above, a lithium battery diaphragm puncture temperature measurement system and a usage method provided by the present invention have the following effects: By monitoring the dynamic temperature, the change of the diaphragm puncture strength with temperature is measured. The puncture temperature of the diaphragm can be accurately reflected through the curve of the puncture strength changing with temperature, improving the accuracy of measuring the diaphragm puncture temperature, avoiding the influence of electrolyte decomposition on the measurement result when measuring the diaphragm puncture temperature during the process of the diaphragm being soaked in the electrolyte, enhancing the accuracy of the measurement result; at the same time, this device also has the advantages of simple structure, low cost, and environmental friendliness. Description of the Drawings

[0013] In order to more clearly illustrate the purpose, technical solution, and beneficial effects of the embodiments of the present invention, the present invention provides the following drawings for illustration.

[0014] Figure 1 It is a schematic diagram of a lithium battery diaphragm puncture temperature measurement system.

[0015] Figure 2 It is a schematic diagram of the diaphragm clamp used in a lithium battery diaphragm puncture temperature measurement system.

[0016] Figure 3 It is a schematic diagram of the curve of the diaphragm puncture strength changing with temperature.

[0017] In the figure, 1. heating device, 2. puncturing device, 3. diaphragm, 4. measuring device, 5. control and data acquisition and processing device, 21. diaphragm clamp, 22. puncturing needle, 211. lower diaphragm clamp, 212. upper diaphragm clamp, 213. cylindrical needle hole, 41. temperature detection device, 42. puncturing strength detection device, 51. control module, 52. data acquisition and processing module. Specific embodiments

[0018] The present invention provides a lithium battery diaphragm film-breaking temperature measurement system and a usage method. To deepen the understanding of the present invention, the following further details the present invention with reference to the accompanying drawings. This embodiment is only used to explain the present invention and does not limit the protection scope of the present invention.

[0019] As shown in Figure 1 The present invention provides a lithium battery diaphragm film-breaking temperature measurement system, which includes: a heating device 1, a puncturing device 2, a diaphragm 3, a measuring device 4, and a control and data acquisition and processing device 5. The puncturing device 2 is composed of a diaphragm clamp 21 and a puncturing needle 22, and the diaphragm clamp 21 is located inside the heating device 1. The diaphragm 3 is clamped inside the diaphragm clamp 21. The puncturing needle 22 is fixed above the diaphragm clamp 21, located inside the heating device 1, and its top is connected to the measuring device 4 and the control and data acquisition and processing device 5 through electrical signals. The measuring device 4 is composed of a temperature detection device 41 and a puncturing strength detection device 42. The temperature detection device 41 is located inside the heating device 1; the puncturing strength detection device 42 is used to measure the puncturing strength of the diaphragm 3 as the puncturing needle descends. The control and data acquisition and processing device 5 is composed of a control module 51 and a data acquisition and processing module 52. The control module 51 can control and adjust the temperature of the heating device 1 and control the movement of the puncturing needle 22. The heating device 1 and the puncturing device 2 are connected to the control module 51 through electrical signals, and the measuring device 4 is connected to the data acquisition and processing module 52 through electrical signals.

[0020] As an example, the heating device 1 is one of an oven and an electric furnace.

[0021] As an example, as shown in Figure 2As shown, the diaphragm clamp 21 includes a lower diaphragm clamp 211 and an upper diaphragm clamp 212, and the shape of the diaphragm clamp 21 is a cuboid or a cylinder; the shape and size of the diaphragm clamp 21 match the shape and size of the diaphragm 3. Preferably, the size of the diaphragm clamp 21 should be slightly smaller than the size of the diaphragm 3 to ensure that the diaphragm 3 can be clamped between the lower diaphragm clamp 211 and the upper diaphragm clamp 212 to ensure the flatness of the diaphragm 3 during measurement. The lower diaphragm clamp 211 and the upper diaphragm clamp 212 have at least two cylindrical pinholes 213 of the same shape, and the cylindrical pinholes 213 need to correspond to each other in the upper and lower positions of the lower diaphragm clamp 211 and the upper diaphragm clamp 212. Preferably, the diameter of the cylindrical pinhole 213 is 10-20 mm.

[0022] As an example, the puncture needle 22 has a smooth surface without burrs, a diameter of 0.5-1.0 mm, a descending speed of 50-500 mm / min, and is connected to the control module 51 via an electrical signal.

[0023] As an example, Figure 1 As shown, the measuring device 4 includes a temperature detection device 41 and a puncture strength detection device 42. The temperature detection device 41 is located within the heating device 1 and is used to measure the temperature within the heating device 1. The puncture strength detection device 42 is located on one side of the heating device 1 and is used to detect the puncture resistance of the diaphragm 3. By detecting the pressure of the diaphragm 3, the puncture strength of the diaphragm 3 is obtained. The temperature detection device 41 can be a temperature detection device built into the heating device 1 itself, or it can be an additional temperature detection device.

[0024] As an example, the temperature detection device 41 is a thermocouple temperature sensor or an infrared temperature sensor.

[0025] As an example, the control and data acquisition and processing device 5 includes a control module 51 and a data acquisition and processing module 52; wherein, the control module 51 is connected to the heating device 1 and the puncture device 2 via electrical signals, and is used to control the operation of the heating device 1 and the puncture device 2; the data acquisition and processing module 52 is connected to the measuring device 4 via electrical signals, and is used to collect and process the temperature of the heating device 1 detected by the temperature detection device 41 and the puncture strength of the diaphragm 3 detected by the puncture strength detection device 42, and obtain the relationship between the puncture strength of the diaphragm 3 and the temperature through processing.

[0026] like Figure 3As shown in the figure, the working principle of the lithium battery separator film breakage temperature measurement system of the present invention is as follows: During the measurement process, when the temperature in the heating device 1 is lower than the melting point of the separator 3, the separator 3 is uniform, and the puncture resistance of the separator does not change significantly with the increase in temperature. When the temperature in the heating device 1 reaches a high enough level to cause the separator 3 to break, the separator 3 is damaged. At this time, the puncture resistance of the separator 3 is greatly reduced, and the measured value of the puncture strength detection device 42 decreases. Since the temperature detection device 41 can detect the temperature of the heating device 1 in real time during the measurement process, and at the same time, the control module 51 can control the position of the puncture needle as the temperature inside the heating device 1 changes, so as to realize the real-time detection of the puncture strength of the separator 3. The lithium battery separator film breakage temperature measurement system of the present invention can accurately characterize the breakage temperature of the separator 3 according to the change of the puncture strength of the separator 3 with temperature. The judgment criterion is: the temperature point at which the puncture strength of the separator 3 decreases sharply is the breakage temperature of the separator 3.

[0027] A method for using a lithium battery separator film breakage temperature measurement system of the present invention includes the following steps connected in sequence:

[0028] A. Cut the separator (3) into a rectangular sample with a length of 100 mm and a width of 50 mm, and clamp it inside the separator fixture (21);

[0029] B. Set the initial temperature of the heating device (1) to 125 °C, the heating rate to 5 °C / min, and then power on the heating device (1);

[0030] C. Set the temperature detection device (41) and the puncture strength detection device (42) to the same step size of 50 seconds, collect the temperature value and the puncture strength value, and the computer interface displays the temperature-puncture strength change curve in real time;

[0031] D. As the temperature of the heating device (1) rises, the temperature of the separator rises accordingly. When the temperature rises to the range of 140 - 170 °C, the puncture strength of the separator (3) gradually decreases. When the puncture strength basically does not change with the temperature change, the temperature at this time is the breakage temperature of the separator. Figure 3 Points A and B in the figure respectively represent the breakage temperatures of the PE-based film and the ceramic-coated film.

[0032] The lithium battery separator film breakage temperature measurement system of the present invention can accurately measure the change of the puncture strength of the separator with temperature. The breakage temperature of the separator can be accurately reflected through the turning point of the puncture strength of the separator, avoiding the influence of the decomposition of the electrolyte on the measurement result when measuring the breakage temperature of the separator by soaking the separator in the electrolyte, making the measurement result have high accuracy; at the same time, the lithium battery separator film breakage temperature measurement system of the present invention also has the advantages of simple structure, low cost, and easy operation.

[0033] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements or changes made within the technical scope disclosed by the present invention according to the technical solution and inventive concept of the present invention shall be included within the protection scope of the present invention.

Claims

1. A lithium battery separator film breaking temperature measurement system, characterized in that: It includes a heating device (1), a puncturing device (2), a diaphragm (3), a measuring device (4), and a control and data acquisition and processing device (5). The puncturing device (2) consists of a diaphragm clamp (21) and a puncturing needle (22). The diaphragm clamp (21) is located inside the heating device (1). The puncturing needle (22) is fixed above the diaphragm clamp (21), located inside the heating device (1), and its top is connected to the measuring device (4) and the control and data acquisition and processing device (5) through electrical signals. The measuring device (4) consists of a temperature detection device (41) and a puncturing strength detection device (42). The temperature detection device (41) is used to measure the temperature of the heating device (1) and is located inside the heating device (1). The puncturing strength detection device (42) is used to measure the puncturing strength of the diaphragm (3). The control and data acquisition and processing device (5) is connected to the heating device (1), the puncturing device (2), and the measuring device (4) through electrical signals. The heating rate of the heating device (1) is 0.2 - 10 °C / min. The diaphragm clamp (21) consists of two parts, a lower diaphragm clamp (211) and an upper diaphragm clamp (212). The diaphragm (3) is clamped between the lower diaphragm clamp (211) and the upper diaphragm clamp (212). The diaphragm clamp (21) has at least 2 cylindrical needle holes (213) with the same shape, and the diameter of the cylindrical needle holes (213) is 10 - 20 mm. The cylindrical needle holes (213) are vertically corresponding in the lower diaphragm clamp (211) and the upper diaphragm clamp (212). The puncturing needle (22) is smooth and burr-free, with a diameter of 0.5 - 1.0 mm and a descending speed of 50 - 500 mm / min.

2. The lithium battery separator film breakage temperature measurement system according to claim 1, wherein The heating device (1) is one of an oven and an electric furnace.

3. The lithium battery separator film breakage temperature measurement system according to claim 1, wherein, The shape of the diaphragm clamp (21) is one of a cuboid and a cylinder.

4. A lithium battery separator film breakage temperature measurement system according to claim 1, characterized in that, The temperature detection device (41) is a thermocouple temperature sensor or an infrared temperature sensor.

5. The lithium battery separator film breakage temperature measurement system according to claim 1, characterized in that, The control and data acquisition and processing device (5) consists of a control module (51) and a data acquisition and processing module (52). The control module (51) is connected to the heating device (1) and the puncturing device (2) through electrical signals to control the temperature rise and fall of the heating device (1) and the position movement of the puncturing needle (22). The data acquisition and processing module (52) is connected to the measuring device (4) through electrical signals to collect the data detected by the measuring device (4).

6. A method for using the lithium battery separator film breakage temperature measurement system according to claim 1, characterized in that, It includes the following steps connected in sequence: A. Cut the diaphragm (3) into a rectangular sample with a length of 100 mm and a width of 50 mm, and clamp it inside the diaphragm clamp (21). B. Set the initial temperature of the heating device (1) to 125 °C and the heating rate to 5 °C / min, and then power on the heating device (1). C. Set the same step size of 50 seconds for the temperature detection device (41) and the puncturing strength detection device (42), collect the temperature values and puncturing strength values, and the temperature-puncturing strength change curve is displayed in real time on the computer interface. D. As the temperature of the heating device (1) increases, the temperature of the diaphragm also increases. When the temperature rises to the range of 140°C - 170°C, the puncture strength of the diaphragm (3) gradually decreases. When the puncture strength remains basically unchanged with the change of temperature, the temperature at this time is the diaphragm rupture temperature.

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