Device and method for representing thermal puncture behavior of diaphragm

Abstract

The invention discloses a device and a method for representing thermal puncture behavior of a diaphragm, and relates to the technical field of lithium battery detection, the device comprises a chassis, a heating assembly, a clamping assembly and a penetrating assembly, the chassis is provided with the heating assembly, the heating assembly is used for heating the diaphragm at high temperature, the heating assembly is internally provided with the clamping assembly, and the clamping assembly is used for fixing a soft diaphragm; a penetrating assembly is arranged on the heating assembly and used for puncturing the soft film, an iron plate is arranged on the base plate, the iron plate is fixedly connected with the base plate, and the iron plate is electrically connected with an external power source.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery detection, and in particular to a device and method for characterizing thermal puncture behavior of a diaphragm. Background Art

[0002] In recent years, the safety (thermal runaway) problem of power batteries has become the main obstacle to the rapid promotion of new energy vehicles. Under abuse conditions, the internal temperature of the lithium battery rises, causing the SEI layer to decompose and release heat, which accelerates the heating process. This vicious cycle leads to the softening of the diaphragm. The softened diaphragm is pierced by the protrusions on the surface of the electrode (such as the lithium dendrites of the negative electrode), causing the positive and negative electrodes to contact each other, which is the so-called internal short circuit. The internal short circuit causes the current inside the battery to increase sharply, instantly generating a large amount of Joule heat. The battery temperature rises rapidly in a very short time, exceeding the ignition point of the electrolyte, thereby causing the battery to catch fire and explode. It can be seen that the thermal penetration performance of the diaphragm in a high-temperature environment greatly affects the safety performance of the power battery.

[0003] However, the diaphragm industry currently uses universal tensile testing machines at room temperature to test the puncture strength of diaphragms. However, a diaphragm with high puncture strength at room temperature may not necessarily have high puncture strength at high temperatures, and vice versa. The high-temperature puncture strength of the diaphragm is the direct factor that determines the safety of power batteries. However, there is currently no instrument or method in the industry that specifically characterizes the thermal puncture behavior of diaphragms. Summary of the Invention

[0004] The object of the present invention is to provide a device and method for characterizing the thermal puncture behavior of a diaphragm, so as to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions: A device for characterizing the thermal puncture behavior of a diaphragm. The device is used to detect the puncture resistance of a lithium battery diaphragm under high temperature conditions, or to detect the puncture temperature of a lithium battery diaphragm under constant puncture force and programmed temperature rise. The device includes a chassis, a heating component, a clamping component, and a penetration component. The chassis is provided with a heating component, which is used to heat the diaphragm at high temperature. The heating component is provided with a clamping component, which is used to fix a soft film. The heating component is provided with a penetration component, which is used to perform a puncture process on the soft film. The chassis is provided with an iron plate, which is fixedly connected to the chassis and electrically connected to an external power supply.

[0006] The device is mainly used to detect the soft film on the lithium battery at high temperature. It detects the puncture resistance of the soft film in the lithium battery. The heating component is used to heat the internal soft film so that the soft film reaches the required temperature requirement. The heating component can also perform programmed temperature increase to detect the puncture temperature of the lithium battery separator under a constant puncture force. The clamping component is used to fix the soft film. The clamping component also performs tension detection on the soft film while fixing it. The penetration component is used to perform the puncture process on the soft film. The iron plate is energized with an external power supply, so that when the puncture needle in the penetration component passes through the soft film, it will contact the iron plate. When the two are in contact, the puncture needle will also form a circuit to energize. The warning light on the connector tells you that the soft film is in a penetration state and the puncture needle is in contact with the chassis, thereby controlling the drive push rod to stop working to prevent damage to the puncture needle.

[0007] Furthermore, the heating assembly includes a shell, a heating element and a cover door, the shell is fixedly connected to the upper surface of the chassis, the heating element is located inside the shell, the fixed end of the heating element is fixedly connected to the inner wall of the shell, the cover door is rotatably connected to the shell, and a through hole is opened on the cover door.

[0008] The shell, cover door and chassis form an enclosed space to improve heating efficiency. The heating element is located inside the shell. When the cover door is closed, it is used to heat the soft film inside the shell. When it needs to be placed or taken, the cover door is opened. The cover door is made of transparent material. The staff can observe the working status inside the shell through the cover door. The through hole is used for the puncture needle to pass through. The number of through holes is the same as that of the puncture needle, and the corresponding through hole and the puncture needle are on the same central axis. The through hole is rotated outside to connect the flip door to achieve sealing.

[0009] Furthermore, the clamping assembly includes a slider and a column A. A slide groove is provided on the upper surface of the chassis. The slider is slidably connected to the slide groove. The column A is located at the top of the slider. The bottom end of the column A is fixedly connected to the slider. A hollow cavity is provided in the column A. A hydraulic rod is provided in the column A. There are two hydraulic rods, which are located at the top and bottom ends of the inner wall of the hollow cavity. The hydraulic rods are on the same central axis. A fastener is provided at the output end of the hydraulic rod, and the fastener is clamped and connected to the output end of the hydraulic rod.

[0010] The slide is located on the upper surface of the chassis, and there are four slides located at the four corners of the chassis. The column A is the main structure of the clamping assembly. Then, the hydraulic rod is used as the power end to control the movement of the fastener. The hydraulic rod has two top and bottom ends located in the hollow cavity. The fixed end of one hydraulic rod is fixedly connected to the top of the hollow cavity, and the output end is downward. The fixed end of the other hydraulic rod is fixedly connected to the bottom of the hollow cavity, and the output end is upward. Fasteners are provided at the output ends of the two hydraulic rods. The fasteners have a variety of shapes, so that different fastening effects and fastening forces can be achieved through their shape structures. When the hydraulic rod is working, the fastener at the output end moves toward the soft membrane, and finally the fastening purpose is achieved.

[0011] Furthermore, a spring A is provided on one side of the inner wall of the chute, one end of the spring A is fixedly connected to the inner wall of the chute, and the other end of the spring A is fixedly connected to the slider. A slave plate is provided on the inner wall of the chute, and a main plate is provided on the slider. The main plate is located on the side of the slider close to the slave plate. The penetration component includes a column B and a puncture needle. The column B is fixedly connected to the upper surface of the chassis, a top plate is provided on the top of the column B, and the column B is fixedly connected to the top plate. A driving push rod is provided at the bottom end of the top plate, and the fixed end of the driving push rod is fixedly connected to the bottom end of the top plate. The output end of the driving push rod is provided with a connector, and the connector is fixedly connected to the output end of the driving push rod. The puncture needle position At the bottom end of the connector, the puncture needle is connected to the connector bolt, and the puncture needle cooperates with the through hole. A spring B is provided on the connector, one end of the spring B is fixedly connected to the connector, and the other end of the spring B is fixedly connected to the puncture needle. A strain gauge is provided in the spring B, and the strain gauge is fixedly connected to the connector. An extrusion column is provided at one end of the puncture needle, and the extrusion column is located at one end of the extrusion column close to the puncture needle. The extrusion column fits the strain gauge. A warning light is provided on the connector, and the warning light is electrically connected to the puncture needle. The puncture needle contacts the iron plate to form a circuit to energize the warning light. A control terminal is provided on the shell, and a control panel is provided in the control terminal.

[0012] When the slider moves, it will drive one end of spring A and the main plate to move. As the main plate moves, the distance between the main plate and the slave plate will change, thereby changing the capacitance value. The greater the distance between the two values, the smaller the capacitance value. Conversely, the smaller the distance between the two, the larger the capacitance value. According to the change in the capacitance value between the main plate and the slave plate, the moving distance of the slider is known, which is also the elongation value of spring A. Then, the tension value of the soft film is calculated based on the elongation value. The principle is Hooke's theorem. The elongation of spring A is proportional to the tension, that is, F=kx, where F represents the tension. , x represents the elongation of spring A, k is the elastic coefficient of spring A, by measuring the deformation of the elastic element, the tension of the object can be indirectly measured, the column B is the main structure of the penetrating component, perpendicular to the chassis, the top plate is parallel to the horizontal line, the driving push rod is used as the power end to push the connecting piece to move downward, the connecting piece drives the puncture needle to move downward, the driving push rod is perpendicular to the top plate as a whole, and the output end of the driving push rod moves downward, the connecting piece is used to install the puncture needle, the overall size of the puncture needle is the same as the through hole, so that the puncture needle enters the shell through the through hole, and the puncture needle is energized The material is made of a material, and the puncture needle is connected to the connecting piece with a bolt, so that the number of puncture needles can be set according to the needs. When the penetration work is performed, the puncture needle will contact the soft membrane and apply a penetration force to the soft membrane. When the soft membrane is not penetrated, the soft membrane will apply a reverse thrust to the puncture needle, and the puncture needle will be squeezed by the spring B. The spring B retracts, so that the extrusion column will contact the strain gauge, and the extrusion column will squeeze the strain gauge. According to the strain principle, when the conductor or semiconductor material is deformed, its resistance value will also change. The greater the strain, the greater the resistance change. The applied penetration force can be known according to the changed resistance value. When the puncture needle penetrates the soft membrane, the puncture needle will contact the iron plate, and the contact between the puncture needle and the iron plate will form a circuit to energize the warning light. Finally, the warning light is energized and works, and the drive push rod stops working. A control panel is provided in the control terminal. The control terminal is electrically connected to the strain gauge, and the control terminal is electrically connected to the main electrode plate. The data measured by the two will be reflected on the control terminal. The hydraulic rod and the drive push rod are also electrically connected to the control terminal, and the work is controlled by the control terminal. Then the warning light is also electrically connected to the control terminal. When the warning light works, the control terminal controls the drive push rod to stop working.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention controls the operation of a hydraulic rod through a control terminal. The hydraulic rod drives the movement of fasteners, which fix the four corners of the soft film and increase its surface tension. As the soft film stretches, the soft film itself will exert a pulling force on the column A. The slider on the column A will stretch the spring A. The movement distance of the slider is determined by the change in the capacitance between the main electrode plate and the slave electrode plate, which is also the elongation value of the spring A. The pretension value of the soft film is then calculated based on the elongation value.

[0014] 2. When the present invention is performing penetration, the puncture needle will contact the soft membrane and apply a penetrating force to the soft membrane. When the soft membrane is not penetrated, the soft membrane will apply a reverse thrust to the puncture needle, and the puncture needle will be squeezed by spring B. Spring B retracts, so that the squeezing column will contact the strain gauge, and the squeezing column will squeeze the strain gauge. The greater the strain, the greater the resistance change. The applied penetrating force can be determined based on the changed resistance value. The tension of the soft membrane will also change during the penetration process. The tension of the soft membrane reaches its maximum at the moment of penetration, and the tension change value can be determined by the change in the distance of spring A.

[0015] 3. After the puncture needle of the present invention penetrates the soft membrane, it will contact the iron plate on the chassis. Since the iron plate is energized, the puncture needle will contact the iron plate, and the puncture needle will also be energized. The connector connected to the puncture needle will also be energized. Finally, the warning light will be energized and the drive push rod will stop working. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of the present invention as a whole; Figure 2 It is a structural schematic diagram of the chassis of the present invention; Figure 3 This is a schematic structural diagram of a penetration assembly of the present invention; Figure 4 It is a structural schematic diagram of the chute of the present invention; Figure 5 This is a schematic structural diagram of the column A of the present invention; Figure 6 This is a schematic structural diagram of the driving push rod of the present invention; Figure 7 Schematic diagram of the structure of the connecting piece of the present invention; Figure 8 This is the experimental test status table of the present invention; Figure 9 is a table of relative average deviations of the puncture strength of the present invention; Figure 10 This is a table of relative average deviations of the puncture temperature of the present invention.

[0017] In the figure: 1. chassis; 11. slide; 2. heating component; 21. shell; 22. heating element; 23. cover door; 231. through hole; 3. clamping component; 31. slider; 32. column A; 33. hydraulic rod; 34. fastener; 36. spring A; 37. slave plate; 38. main plate; 4. penetration component; 41. column B; 42. puncture needle; 43. top plate; 44. driving push rod; 45. connecting part; 46. spring B; 47. strain gauge; 48. extrusion column; 5. iron plate; 6. warning light; 7. control terminal. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Example

[0019] like Figures 1 to 7 As shown, the present invention provides a device and method technical solution for characterizing the thermal puncture behavior of a diaphragm.

[0020] A device for characterizing the thermal puncture behavior of a diaphragm, the device is used to detect the puncture resistance of a lithium battery diaphragm under high temperature conditions. The device includes a chassis 1, a heating component 2, a clamping component 3 and a penetration component 4. The chassis 1 is provided with a heating component 2, the heating component 2 is used to heat the diaphragm at high temperature, the heating component 2 is provided with a clamping component 3, the clamping component 3 is used to fix the soft film, the heating component 2 is provided with a penetration component 4, the penetration component 4 is used to perform a puncture process on the soft film, the chassis 1 is provided with an iron plate 5, the iron plate 5 is fixedly connected to the chassis 1, and the iron plate 5 is electrically connected to an external power supply.

[0021] Specifically, the device is mainly used to detect the soft film on the lithium battery at high temperature. It detects the puncture resistance of the soft film in the lithium battery. The heating component 2 is used to heat the internal soft film so that the soft film reaches the required temperature requirement. The clamping component 3 is used to fix the soft film. While fixing the soft film, the clamping component 3 also performs tension detection on the soft film. The penetration component 4 is used to perform a puncture process on the soft film. The iron plate 5 is energized with an external power supply, so that when the puncture needle 42 in the penetration component 4 passes through the soft film, it will contact the iron plate 5. When the two are in contact, the puncture needle 42 will also form a circuit to energize. The warning light 6 on the connecting piece 45 tells that the soft film has been penetrated and the puncture needle 42 is in contact with the chassis 1, thereby controlling the driving push rod 44 to stop working to prevent damage to the puncture needle 42.

[0022] like Figure 1 、 Figure 3 As shown, the heating assembly 2 includes a shell 21, a heating element 22 and a cover door 23. The shell 21 is fixedly connected to the upper surface of the chassis 1. The heating element 22 is located inside the shell 21. The fixed end of the heating element 22 is fixedly connected to the inner wall of the shell 21. The cover door 23 is rotatably connected to the shell 21, and a through hole 231 is opened on the cover door 23.

[0023] Specifically, the shell 21, the cover door 23 and the chassis 1 form a closed space to improve the heating efficiency. The heating element 22 is located in the shell 21. When the cover door 23 is closed, it is used to heat the soft film in the shell 21. When it needs to be placed or taken, the cover door 23 is opened. The cover door 23 is made of transparent material. The staff observes the internal working status of the shell 21 through the cover door 23. The through hole 231 is used to cooperate with the puncture needle 42 to pass through. The number of the through holes 231 is the same as that of the puncture needle 42, and the corresponding through holes 231 and the puncture needle 42 are on the same central axis. The through hole 231 is rotated outside to connect to the flip door 23 to achieve sealing.

[0024] like Figures 2 to 5 As shown, the clamping assembly 3 includes a slider 31 and a column A32. A slide groove 11 is provided on the upper surface of the chassis 1. The slider 31 is slidably connected to the slide groove 11. The column A32 is located at the top of the slider 31. The bottom end of the column A32 is fixedly connected to the slider 31. A hollow cavity is provided in the column A32. A hydraulic rod 33 is provided in the column A32. There are two hydraulic rods 33, which are located at the top and bottom ends of the inner wall of the hollow cavity. The hydraulic rods 33 are on the same central axis. A fastener 34 is provided at the output end of the hydraulic rod 33, and the fastener 34 is clamped and connected to the output end of the hydraulic rod 33.

[0025] Specifically, the slide 11 is located on the upper surface of the chassis 1, and the slide 11 is provided with four at the four corners of the chassis 1. The column A32 is the main structure of the clamping assembly 3. Then, the hydraulic rod 33 is used as the power end to control the movement of the fastener 34. The hydraulic rod 33 is provided with two top and bottom ends located in the hollow cavity. The fixed end of one hydraulic rod 33 is fixedly connected to the top of the hollow cavity, and the output end is downward. The fixed end of the other hydraulic rod 33 is fixedly connected to the bottom of the hollow cavity, and the output end is upward. Fasteners 34 are provided at the output ends of the two hydraulic rods 33. The fasteners 34 are provided with a variety of shapes, so that different fastening effects and fastening forces can be achieved through their shape structures. When the hydraulic rod 33 is working, the fastener 34 at the output end moves toward the soft membrane, and finally the fastening purpose is achieved.

[0026] like Figure 2 、 Figure 4 As shown, a spring A36 is provided on one side of the inner wall of the slide groove 11, one end of the spring A36 is fixedly connected to the inner wall of the slide groove 11, and the other end of the spring A36 is fixedly connected to the slider 31. A slave pole plate 37 is provided on the inner wall of the slide groove 11, and a main pole plate 38 is provided on the slider 31. The main pole plate 38 is located on the side of the slider 31 close to the slave pole plate 37.

[0027] Specifically, when the slider 31 moves, it will drive one end of the spring A36 and the main electrode plate 38 to move. Due to the movement of the main electrode plate 38, the distance between the main electrode plate 38 and the slave electrode plate 37 will change, thereby changing the capacitance value. When the distance between the two is larger, the capacitance value is smaller. Conversely, the smaller the distance between the two is smaller, the capacitance value is larger. According to the change in the capacitance value between the main electrode plate 38 and the slave electrode plate 37, the movement distance of the slider 31 is known, which is also the elongation value of the spring A36. Then, the tension value of the soft film is calculated based on the elongation value. The principle is Hooke's theorem. The elongation of the spring A36 is proportional to the tension it receives, that is, F=kx, where F represents the tension it receives, x represents the elongation of the spring A36, and k is the elastic coefficient of the spring A36. By measuring the deformation of the elastic element, the tension of the object can be indirectly measured.

[0028] like Figure 1 、 Figure 3 、 Figure 6 As shown, the penetration component 4 includes a column B41 and a puncture needle 42. The column B41 is fixedly connected to the upper surface of the chassis 1. A top plate 43 is provided at the top of the column B41. The column B41 is fixedly connected to the top plate 43. A driving push rod 44 is provided at the bottom end of the top plate 43. The fixed end of the driving push rod 44 is fixedly connected to the bottom end of the top plate 43. A connecting piece 45 is provided at the output end of the driving push rod 44. The connecting piece 45 is fixedly connected to the output end of the driving push rod 44. The puncture needle 42 is located at the bottom end of the connecting piece 45. The puncture needle 42 is bolted to the connecting piece 45. The puncture needle 42 cooperates with the through hole 231.

[0029] Specifically, the column B41 is the main structure of the through-component 4, which is perpendicular to the chassis 1, and the top plate 43 is parallel to the horizontal line. The driving push rod 44 serves as the power end to push the connecting piece 45 to move downward, and the connecting piece 45 drives the puncture needle 42 to move downward. The driving push rod 44 is perpendicular to the top plate 43 as a whole, and the output end of the driving push rod 44 moves downward. The connecting piece 45 is used to install the puncture needle 42. The overall size of the puncture needle 42 is the same as the through hole 231, so that the puncture needle 42 enters the shell 21 through the through hole 231. The puncture needle 42 is made of an electrified material, and the puncture needle 42 is bolted to the connecting piece 45, so that the number of puncture needles 42 is set according to needs.

[0030] like Figure 7 As shown, a spring B46 is provided on the connecting member 45, one end of the spring B46 is fixedly connected to the connecting member 45, and the other end of the spring B46 is fixedly connected to the puncture needle 42. A strain gauge 47 is provided in the spring B46, and the strain gauge 47 is fixedly connected to the connecting member 45. An extrusion column 48 is provided at one end of the puncture needle 42, and the extrusion column 48 is located at one end of the puncture needle 42 close to the extrusion column 48, and the extrusion column 48 is in contact with the strain gauge 47.

[0031] Specifically, when performing the penetration work, the puncture needle 42 will contact the soft membrane and apply a penetrating force to the soft membrane. When the soft membrane is not penetrated, the soft membrane will apply a reverse thrust to the puncture needle 42, and the puncture needle 42 will be squeezed by the spring B46. The spring B46 retracts, so that the squeezing column 48 will contact the strain gauge 47, and the squeezing column 48 will squeeze the strain gauge 47. According to the strain principle, when a conductor or semiconductor material is deformed, its resistance value will also change. The greater the strain, the greater the resistance change. The applied penetration force can be known based on the changed resistance value.

[0032] like Figure 7 The connector 45 is provided with a warning light 6 , which is electrically connected to the puncture needle 42 . The puncture needle 42 contacts the iron plate 5 to form a circuit, thereby energizing the warning light 6 .

[0033] Specifically, after the puncture needle 42 penetrates the soft membrane, the puncture needle 42 will contact the iron plate 5, so that the puncture needle 42 and the iron plate 5 form a circuit to energize the warning light 6. Finally, the warning light 6 is energized to work, and the driving push rod 44 stops working.

[0034] like Figure 1 The housing 21 is provided with a control terminal 7, and a control panel is provided inside the control terminal 7; Specifically, a control panel is provided in the control terminal 7. The control terminal 7 is electrically connected to the strain gauge 47 and the control terminal 7 is electrically connected to the main electrode plate 38. The data measured by the two will be reflected on the control terminal 7. The hydraulic rod 33 and the driving push rod 44 are also electrically connected to the control terminal 7 and controlled by the control terminal 7. Then the warning light 6 is also electrically connected to the control terminal 7. When the warning light 6 is working, the control terminal 7 controls the driving push rod 44 to stop working.

[0035] Working principle: The staff first opens the cover door 23, then puts the two ends of the soft film on the roller 33, and finally closes the cover door 23. The hydraulic rod 33 is controlled by the control terminal 7 to work. The hydraulic rod 33 drives the fastener 34 to move, and the fastener 34 fixes the four corners of the soft film. Then the heating element 22 is controlled to heat at high temperature. At the same time, due to the stretching of the soft film, the soft film itself will pull the column A32, and the slider 31 on the column A32 will stretch the spring A36. According to the change in the capacitance value between the main electrode 38 and the slave electrode 37, the moving distance of the slider 31 is known, which is also the elongation value of the spring A36. Then, the tension value of the soft film is calculated based on the elongation value, and the push rod 44 is driven to work to push the puncture needle. 42. The puncture needle 42 enters the shell 21 through the through hole 231 and contacts the soft membrane. The driving push rod 44 will continue to work, maintaining a certain thrust, so that the puncture needle 42 punctures the soft membrane. Due to the operation of the heating element 22, the temperature in the shell 21 will continue to rise, and the soft membrane will gradually soften. During the puncture process, the reverse thrust of the puncture needle 42 will cause the extrusion column 48 to apply force to the strain gauge 47. After the puncture needle 42 penetrates the soft membrane, the puncture needle 42 will contact the iron plate 5 on the chassis 1. Because the iron plate 5 is energized, the puncture needle 42 contacts the iron plate 5, the puncture needle 42 will also be energized, and the connecting piece 45 connected to the puncture needle 42 will also be energized. Finally, the warning light 6 is energized and the driving push rod 44 stops working. Example

[0036] A single-needle device with a spherical needle radius of R = 1.0 mm and an annular fixing frame with an outer diameter of 124 mm and a frame width of 12 mm was used. Six fastening clamps were evenly applied around the fixing frame ring with a preload of 1000 N. The puncture force of diaphragms A, B, and C was tested at temperatures of 110°C and 130°C using a step-by-step increase method. The puncture force of diaphragm D was tested at temperatures of 140°C and 160°C using a step-by-step increase method. Each set of tests was performed five times in parallel. Example

[0037] A three-prick needle device was used, with a spherical radius of R = 0.5 mm and an annular fixing frame with an outer diameter of 124 mm and a frame width of 12 mm. Six fastening clamps were evenly applied around the fixing frame ring with a preload of 1000 N. The puncture force of diaphragms A, B, and C was tested at temperatures of 110°C and 130°C using a step-by-step increase method. The puncture force of diaphragm D was tested at temperatures of 140°C and 160°C using a step-by-step increase method. Each set of tests was performed five times in parallel. Example

[0038] A single-needle device with a spherical needle radius of R = 1.0mm and a circular retaining frame with an outer diameter of 124mm and a frame width of 12mm was used. Six clamps were evenly spaced around the retaining frame ring with a preload of 1000N. The puncture temperatures of diaphragms A, B, C, and D were tested using a gradually increasing temperature method under counterweights of 50gf and 100gf, respectively. Each test was performed in parallel five times. Example

[0039] A single-needle device was used, with a spherical radius of R = 0.5 mm and a rectangular fixed frame with an outer diameter of 124 mm × 104 mm and a frame width of 12 mm. Two fastening clips were evenly applied to each of the four sides to fix the diaphragm in the direction of length × width = MD × TD. The long side preload force was 20 N and the short side preload force was 1000 N. The puncture force of diaphragms A, B, and C was tested at temperatures of 110°C and 130°C, respectively, using a step-by-step increase method. The puncture force of diaphragm D was tested at temperatures of 140°C and 160°C, respectively. Each set of tests was conducted five times in parallel. Example

[0040] A three-pronged device was used, with a spherical radius of R = 0.5 mm and a rectangular fixing frame with an outer diameter of 124 mm × 104 mm (length × width = 124 mm × width) and a frame width of 12 mm. Two clamps were evenly applied to each of the four sides to secure the diaphragm along the length × width = MD × TD direction. The preload force on both the long and short sides was 1000 N. The puncture temperatures of diaphragms A, B, C, and D were tested using a gradually increasing temperature method with counterweights of 50 gf and 100 gf, respectively. Each test was performed five times in parallel. Example

[0041] A three-prick device was used, with a spherical radius of R = 1.0 mm and a rectangular fixing frame with an outer diameter of 124 mm × 104 mm and a frame width of 12 mm. Two fastening clamps were evenly applied to each of the four sides to secure the diaphragm along the length × width = MD × TD direction. The long side preload was 20 N, and the short side preload was 1000 N. The puncture temperatures of diaphragms A, B, C, and D were tested using a gradually increasing temperature method under counterweights of 50 gf and 100 gf, respectively. Each set of tests was performed five times in parallel.

[0042] Depend on Figure 8 、 Figure 9 and Figure 10 It can be seen that: whether for different diaphragm samples or for the same diaphragm sample under different test conditions, the average values ​​of puncture strength and puncture temperature measured by the device are very different, and the relative average deviation of parallel test results of the same indicator is small, indicating that the test device can be applied to different scenarios, and the repeatability and reliability of the test results are high.

[0043] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any figure marks in the claims should not be regarded as limiting the claims involved.

Claims

1. A device for characterizing the thermal puncture behavior of a separator, the device being used to detect the puncture resistance strength of a lithium battery separator at high temperatures, characterized in that: The device comprises a chassis (1), a heating component (2), a clamping component (3) and a penetration component (4); the chassis (1) is provided with a heating component (2), the heating component (2) is used for high-temperature heating of the diaphragm; the heating component (2) is provided with a clamping component (3), the clamping component (3) is used for fixing the soft film; the heating component (2) is provided with a penetration component (4), the penetration component (4) is used for performing a puncture process on the soft film; the chassis (1) is provided with an iron plate (5), the iron plate (5) is fixedly connected to the chassis (1), and the iron plate (5) is electrically connected to an external power supply.

2. The device for characterizing the thermal puncture behavior of a diaphragm according to claim 1, characterized in that: The heating assembly (2) comprises a shell (21), a heating element (22) and a cover door (23); the shell (21) is fixedly connected to the upper surface of the chassis (1); the heating element (22) is located inside the shell (21); the fixed end of the heating element (22) is fixedly connected to the inner wall of the shell (21); the cover door (23) is rotatably connected to the shell (21); and a through hole (231) is provided on the cover door (23).

3. The device for characterizing thermal puncture behavior of a diaphragm according to claim 2, characterized in that: The clamping assembly (3) includes a slider (31) and a column A (32). A slide groove (11) is provided on the upper surface of the chassis (1). The slider (31) is slidably connected to the slide groove (11). The column A (32) is located at the top of the slider (31). The bottom end of the column A (32) is fixedly connected to the slider (31). A hollow cavity is provided in the column A (32). A hydraulic rod (33) is provided in the column A (32). Two hydraulic rods (33) are provided and are located at the top and bottom ends of the inner wall of the hollow cavity. The two hydraulic rods (33) are on the same central axis. A fastener (34) is provided at the output end of the hydraulic rod (33). The fastener (34) is clamped and connected to the output end of the hydraulic rod (33).

4. The device for characterizing thermal puncture behavior of a diaphragm according to claim 3, characterized in that: A spring A (36) is provided on one side of the inner wall of the chute (11), one end of the spring A (36) is fixedly connected to the inner wall of the chute (11), and the other end of the spring A (36) is fixedly connected to the slider (31). A slave pole plate (37) is provided on the inner wall of the chute (11), and a main pole plate (38) is provided on the slider (31). The main pole plate (38) is located on the side of the slider (31) close to the slave pole plate (37). The penetration component (4) includes a column B (41) and a puncture needle (42). The column B (41) is fixedly connected to the upper surface of the chassis (1), the top of the column B (41) is provided with a top plate (43), the column B (41) is fixedly connected to the top plate (43), the bottom of the top plate (43) is provided with a driving push rod (44), the fixed end of the driving push rod (44) is fixedly connected to the bottom end of the top plate (43), the output end of the driving push rod (44) is provided with a connecting piece (45), the connecting piece (45) is fixedly connected to the output end of the driving push rod (44), and the puncture needle (42) is located at the connecting piece. At the bottom end of the connector (45), the puncture needle (42) is bolted to the connector (45), the puncture needle (42) is matched with the through hole (231), a spring B (46) is provided on the connector (45), one end of the spring B (46) is fixedly connected to the connector (45), the other end of the spring B (46) is fixedly connected to the puncture needle (42), a strain gauge (47) is provided inside the spring B (46), the strain gauge (47) is fixedly connected to the connector (45), the puncture needle (42) An extrusion column (48) is provided at one end, and the extrusion column (48) is located at one end of the puncture needle (42) close to the extrusion column (48). The extrusion column (48) is in contact with the strain gauge (47). A warning light (6) is provided on the connecting piece (45). The warning light (6) is electrically connected to the puncture needle (42). The puncture needle (42) contacts the iron plate (5) to form a circuit to energize the warning light (6). A control terminal (7) is provided on the housing (21), and a control panel is provided in the control terminal (7).

5. The method for characterizing the thermal puncture behavior of a diaphragm according to claim 4, characterized in that: The method comprises the following steps: S1. The staff first opens the cover door (23), installs the required puncture needle (42) and the fastener (34) in the corresponding position, then places the two ends of the soft membrane between the two fasteners (34), and finally closes the cover door (23); S2, controlling the hydraulic rod (33) to work through the control terminal (7), the hydraulic rod (33) drives the fastener (34) to move, the fastener (34) fixes the four corners of the soft film, so that the soft film as a whole generates a clamping force, and then controls the heating element (22) to perform high-temperature heating, and at the same time, the soft film is subjected to a tensile force, which will apply force to the two end columns A (32), and the column A (32) will move. The tension value is obtained by the change in the capacitance value between the main plate (38) on the slider (31) and the slave plate (37) on the slide groove (11), and the push rod (44) is driven to work, pushing the puncture needle (42), and the puncture needle (42) enters the shell (21) through the through hole (231); S3, the puncture needle (42) enters the housing (21) and contacts the soft membrane, the driving push rod (44) will continue to work, maintain a certain thrust, so that the puncture needle (42) punctures the soft membrane, and because the heating element (22) works, the temperature in the housing (21) will continue to rise, and the soft membrane will gradually soften. During the puncture process, the reverse thrust of the puncture needle (42) will cause the extrusion column (48) to apply force to the strain gauge (47), and the puncture force is obtained through the change of the strain gauge (47); S4. After the puncture needle (42) penetrates the soft membrane, the puncture needle (42) will contact the iron plate (5) on the chassis (1). Since the iron plate (5) is energized, the puncture needle (42) will contact the iron plate (5), and the puncture needle (42) will also be energized. The connecting piece (45) connected to the puncture needle (42) will also be energized. Finally, the warning light (6) will be energized and work, and the driving push rod (44) will stop working.

6. The method for characterizing thermal puncture behavior of a diaphragm according to claim 5, characterized in that: The puncture needle (42) is a single needle or a triple needle, and the spherical radius of the puncture needle (42) is 0.5-1.0 mm.

7. The method for characterizing thermal puncture behavior of a diaphragm according to claim 5, characterized in that: The test temperature range is room temperature ~ 320℃, and the test strength range is: 200 ~ 600gf.

8. The method for characterizing thermal puncture behavior of a diaphragm according to claim 5, characterized in that: The fastener (34) is a circular fixed frame or a rectangular fixed frame.

9. A method for characterizing the thermal puncture behavior of a diaphragm according to claim 8, characterized in that The test conditions are as follows: when the fastener (34) is a circular fixing frame, the outer diameter is 124 mm, the frame width is 12 mm, and fastening clamps are evenly arranged around the circular fixing frame, and the pre-tightening force is adjusted. The pre-tightening force is adjusted to any of the following conditions: (1) Preload force 1000N; (2) Preload force 1000N, counterweight 50gf and / or 100gf.

10. The method for characterizing thermal puncture behavior of a diaphragm according to claim 9, characterized in that: When the fastener (34) is a rectangular fixed frame, length x width = 124mm x 104mm / frame width 12mm, fastening clips are provided on both the long side and the short side of the rectangular fixed frame, and the pre-tightening force is adjusted. The pre-tightening force is adjusted to any of the following conditions: (1) Long side preload 20N, short side preload 1000N; (2) The preload force on both the long and short sides is 1000N, and the counterweight is 50gf and / or 100gf; (3) Long side preload 20N, short side preload 1000N, counterweight 50gf and / or 100gf.

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