A puncture device and method for testing the puncture strength of lithium battery diaphragm

Abstract

A puncture device for testing the puncture strength of a lithium battery diaphragm comprises a detection bracket, the detection bracket comprises an upper base, a guide rod and a lower base; the surface of the lower base is vertically provided with a guide rod, the top end of the guide rod is on the upper base, the outer wall of the guide rod is slidably mounted with a slide seat, a ejector pin is vertically provided at the center of the bottom surface of the slide seat, an upper clamp is detachably mounted on the outer wall of the bottom end of the ejector pin, a lower clamp is mounted at the bottom of the upper clamp, a diaphragm with the same outer diameter is arranged at the top of the lower clamp, the diaphragm is embedded in the upper clamp, and the interior of the lower clamp is provided with air guide holes distributed in a ring array; when the diaphragm of the present invention is placed on the lower clamp, the force is more uniform, the fitting effect with the clamp is better, and the accuracy and reproducibility of the test are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium battery processing, and in particular relates to a puncture device and method for testing the puncture strength of a lithium battery diaphragm. Background Art

[0002] Battery separator is one of the important raw materials of lithium-ion batteries and plays an important role in ensuring the performance and safety of lithium-ion batteries. The quality of its performance determines the interface structure and internal resistance of the battery, which in turn affects the key characteristics of the battery such as capacity, cycle performance, and charge and discharge current density. At the same time, during the manufacturing process, due to factors such as uneven electrode surface coating, burrs on the electrode edges, and limited process level during assembly, the separator needs to withstand great pressure. In order to prevent short circuits, the separator is required to have considerable puncture strength.

[0003] When testing with the existing test fixture, it was found that the diaphragm was fixed by the lock between the upper and lower fixtures. The diaphragm would move when the lock was turned. The poor fit between the diaphragm and the fixture resulted in uneven force. The test results of different operators varied greatly, and the data fluctuated greatly, which seriously interfered with the accuracy and reproducibility of the test. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a puncture device for testing the puncture strength of a lithium battery diaphragm. The specific technical solution is as follows:

[0005] A puncture device for testing the puncture strength of a lithium battery diaphragm, comprising a detection bracket, the detection bracket comprising an upper base, a guide rod and a lower base; the surface of the lower base is vertically provided with a guide rod, the top end of the guide rod is an upper base, the outer wall of the guide rod is slidably mounted with a slide seat, a top pin is vertically provided at the center of the bottom surface of the slide seat, an upper clamp is detachably mounted on the outer wall of the bottom end of the ejector pin, a lower clamp is mounted at the bottom of the upper clamp, a diaphragm with the same outer diameter is arranged at the top end of the lower clamp, the diaphragm is embedded in the upper clamp, and air guide holes distributed in a circular array are opened inside the lower clamp, the top end openings of the air guide holes are placed at the bottom of the diaphragm, and the bottom end openings of each of the air guide holes are connected to a vacuum mechanism, and the vacuum mechanism is used to negatively pressure adsorb the diaphragm.

[0006] Furthermore, the upper clamp includes a ring plate part and a top plate part, the top of the ring plate part is provided with a top plate part, the inner wall of the ring plate part is provided with a clamping assembly, the clamping assembly is used to press the diaphragm from the top down, the bottom end of the ring plate part is provided with a lower positioning assembly, the center of the top plate part is provided with an opening for the ejector pin to pass through, the interior of the opening is provided with an upper positioning assembly, the upper positioning assembly and the lower positioning assembly perform alternating locking actions; the upper positioning assembly is used to fix the upper clamp and the ejector pin as a whole, and the lower positioning assembly is used to fix the upper clamp and the lower clamp as a whole.

[0007] Furthermore, the clamping assembly includes a pressure plate and a spring. The inner wall of the ring plate portion is provided with a slide groove distributed in a circular array. A pressure plate is slidably installed inside the slide groove. A spring is provided at the bottom of the pressure plate and embedded in the slide groove.

[0008] Furthermore, the upper positioning component includes a first positioning strip and a first socket. The inner wall of the opening is provided with first positioning strips distributed in a circular array. The first socket is provided at the bottom end of the ejector pin. The first positioning strip is inserted into the first socket from the top. The side section of the first positioning strip is in the shape of a letter "L". The first positioning strip and the first socket are positioned by card mounting or magnetic adsorption.

[0009] Furthermore, the bottom end of the ejector pin is a hemispherical structure, and the first socket is located on the top of the hemispherical structure.

[0010] Furthermore, the lower positioning assembly includes a second positioning strip and a second socket. The second positioning strip is arranged in a circular array on the bottom surface of the ring plate part, the second socket is arranged on the outer wall of the lower clamp, the second positioning strip is inserted into the interior of the second socket, and the second positioning strip and the second socket are positioned by card-fitting or magnetic adsorption.

[0011] A puncture method for testing the puncture strength of a lithium battery separator, the puncture method comprising the following steps:

[0012] S1. Place the diaphragm to be tested;

[0013] Cut the diaphragm sample according to the outer diameter of the fixture;

[0014] Place the diaphragm sample on the top of the lower fixture;

[0015] Set test parameters;

[0016] S2, compress the diaphragm;

[0017] The ejector pin moves downward, thereby driving the upper fixture on the outer wall of its bottom end to move downward;

[0018] The pressing plate is attached to the top surface of the diaphragm sample. The pressing plate is forced to slide upward along the slide groove and compress the spring. At the same time, the pressing plate presses down the diaphragm sample to eliminate the gap between the diaphragm sample and the lower fixture.

[0019] During the sliding of the pressing plate, the vacuum mechanism is started, the air in the air guide hole is extracted by the vacuum mechanism, and the diaphragm sample is fixed on the top of the lower fixture by negative pressure;

[0020] The pressure plate slides to the top, and the ball head of the ejector pin has not yet applied force to the diaphragm. The lower positioning assembly is locked to connect the upper fixture and the lower fixture as a whole. The upper positioning assembly is unlocked to separate the upper fixture from the ejector pin.

[0021] S3, puncture test;

[0022] The ejector needle slides downward at a constant speed according to the set parameters until it pierces the diaphragm;

[0023] After the puncture action is completed, the ejector pin is separated from the lower fixture, and when the ejector pin moves to the position of the top surface of the diaphragm, the lower positioning component is unlocked and the upper positioning component is locked;

[0024] The ejector pin drives the upper fixture to move upward, and the upper fixture is separated from the lower fixture.

[0025] The beneficial effects of the present invention are that when the diaphragm is placed on the lower fixture, the force is more uniform, the fit effect with the fixture is better, and the accuracy and reproducibility of the test are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram showing the structure of a puncture device for testing the puncture strength of a lithium battery separator according to the present invention;

[0027] Figure 2 The overall top view of the lower clamp of the present invention is shown;

[0028] Figure 3 A schematic diagram of the upper clamp structure of the present invention is shown;

[0029] Figure 4 The present invention shows Figure 1 A schematic diagram of the enlarged structure at point A;

[0030] Figure 5 The present invention shows Figure 1 A schematic diagram of the enlarged structure at B;

[0031] As shown in the figure: 1. detection bracket; 11. upper base; 12. guide rod; 13. lower base; 2. slide seat; 3. ejector pin; 31. first socket; 311. first electromagnet; 4. upper fixture; 41. opening; 411. first positioning strip; 42. slide groove; 421. spring; 422. pressure plate; 43. second positioning strip; 5. diaphragm; 6. lower fixture; 61. air guide hole; 62. second socket; 621. second electromagnet; 7. vacuum mechanism. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] like Figure 1As shown, a puncture device for testing the puncture strength of a lithium battery diaphragm comprises a detection bracket 1, wherein the detection bracket 1 comprises an upper base 11, a guide rod 12 and a lower base 13; the surface of the lower base 13 is vertically provided with a guide rod 12, the top of the guide rod 12 is on the upper base 11, a slide 2 is slidably mounted on the outer wall of the guide rod 12, and an ejector pin 3 is vertically provided at the center of the bottom surface of the slide 2; the slide slides up and down along the guide rod to drive the ejector pin to follow the movement;

[0034] An upper clamp 4 is detachably mounted on the outer wall of the bottom end of the ejector pin 3, a lower clamp 6 is mounted on the bottom of the upper clamp 4, a diaphragm 5 with the same outer diameter is disposed on the top end of the lower clamp 6, the diaphragm 5 is embedded in the upper clamp 4, and air guide holes 61 distributed in a circular array are provided inside the lower clamp 6, the top openings of the air guide holes 61 are placed at the bottom of the diaphragm 5, and the bottom openings of each of the air guide holes 61 are connected to a vacuum mechanism 7, and the vacuum mechanism 7 is used for negative pressure adsorption of the diaphragm 5; the air guide holes can be used to non-destructively position the diaphragm, thereby avoiding the upper clamp from shifting during installation, thereby improving the positioning strength, which can not only conveniently and quickly test the puncture strength of the lithium-ion battery diaphragm, but also ensure the accuracy and reproducibility of the test under the conditions of good fitting effect with the clamp and uniform force.

[0035] like Figure 1 and Figure 3 As shown, the upper clamp 4 includes a ring plate part and a top plate part, the top of the ring plate part is provided with a top plate part, the inner wall of the ring plate part is provided with a clamping assembly, the clamping assembly is used to press the diaphragm 5 from the top down, the bottom end of the ring plate part is provided with a lower positioning assembly, the center of the top plate part is provided with an opening 41 for the ejector pin to pass through, the interior of the opening 41 is provided with an upper positioning assembly, the upper positioning assembly and the lower positioning assembly are alternately locked; the upper positioning assembly is used to fix the upper clamp 4 and the ejector pin 3 as a whole, and the lower positioning assembly is used to fix the upper clamp 4 and the lower clamp 6 as a whole; the clamping assembly can be used to position the diaphragm, and the upper positioning assembly can realize that the upper clamp can be moved down together with the ejector pin for vertical assembly without separate installation, thereby ensuring assembly accuracy and avoiding the diaphragm from being deviated during assembly. At the same time, vertical clamping assembly can also be realized, eliminating the problem of easily deviating the diaphragm during rotation and buckle assembly;

[0036] The setting of the lower positioning component can prevent the upper clamp from rotating under force, and at the same time ensure that the upper clamp and the lower clamp are fixed as one during the puncture process, thereby improving the positioning strength of the diaphragm and preventing the ejector pin from being subjected to forces other than the diaphragm during the puncture process, thereby ensuring the accuracy of puncture detection.

[0037] like Figure 4As shown, the clamping assembly includes a pressure plate 422 and a spring 421. The inner wall of the ring plate part is provided with a slide groove 42 distributed in a circular array. The inside of the slide groove 42 is slidably installed with a pressure plate 422. The bottom of the pressure plate 422 is provided with a spring 421, and the spring 421 is embedded in the slide groove 42. When the pressure plate slides upward, the spring is compressed, so that the pressure plate presses the diaphragm in the reverse direction.

[0038] like Figure 5 As shown, the upper positioning component includes a first positioning strip 411 and a first socket 31. The inner wall of the opening 41 is provided with first positioning strips 411 distributed in a circular array. The first socket 31 is provided at the bottom end of the ejector pin 3. The first positioning strip 411 is inserted into the first socket 31 from the top. The side section of the first positioning strip 411 is in the shape of a figure 7. The first positioning strip 411 and the first socket 31 are positioned by snap-fitting or magnetic adsorption. The cooperation between the first positioning strip and the second socket can realize rapid assembly and positioning. The figure 7 structure and insertion from the top can ensure that the ejector pin can be separated from the upper fixture when it moves downward and can lift the upper fixture when it moves upward.

[0039] The first positioning bar 411 has magnetic material built therein, and a first electromagnet 311 is disposed at the inner bottom end of the first socket 31 . The first electromagnet 311 is adsorbed and fixed to the first positioning bar 411 .

[0040] The bottom end of the ejector pin 3 is a hemispherical structure, and the first socket 31 is located on the top of the hemispherical structure.

[0041] The lower positioning assembly includes a second positioning bar 433 and a second socket 62. The second positioning bar 433 is arranged in an annular array on the bottom surface of the ring plate portion, and the second socket 62 is arranged on the outer wall of the lower fixture 6. The second positioning bar 433 is inserted into the interior of the second socket 62. The second positioning bar 433 and the second socket 62 are positioned by snap-fitting or magnetic adsorption. The cooperation between the second positioning bar and the second socket can realize the two functions of anti-rotation and anti-separation.

[0042] There are five second positioning strips, five second sockets and five air guide holes distributed in a circular array.

[0043] The second positioning bar 433 has magnetic material built therein, and a second electromagnet 621 is disposed inside the second socket 62 . The second positioning bar 433 is fixed to the second electromagnet 621 by adsorption.

[0044] A puncture method for testing the puncture strength of a lithium battery separator, the puncture method comprising the following steps:

[0045] S1. Place the diaphragm to be tested;

[0046] Cut the diaphragm sample according to the outer diameter of the fixture;

[0047] Place the diaphragm sample on the top of the lower fixture;

[0048] Set the test parameters; puncture speed 50mm / min, puncture needle displacement 7mm;

[0049] S2, compress the diaphragm;

[0050] The ejector pin 3 moves downward, thereby driving the upper fixture 4 on the outer wall of its bottom end to move downward;

[0051] The pressing plate 422 is attached to the top surface of the diaphragm sample. The pressing plate 422 is forced to slide upward along the slide groove 42 and compress the spring 421. At the same time, the pressing plate 422 presses down the diaphragm sample to eliminate the gap between the diaphragm sample and the lower clamp 6. This process is used to further compress the diaphragm and eliminate the gap to ensure the negative pressure fixing strength in the next step. If there is a gap, the negative pressure adsorption cannot be fully achieved, and the displacement of the diaphragm during subsequent actions is also avoided.

[0052] During the upward sliding of the pressing plate 422, the vacuum mechanism 7 is activated to extract the air in the air guide hole 61, and the diaphragm sample is fixed to the top of the lower fixture 6 by negative pressure; the vacuum mechanism can suck away the air in the air guide hole, so that the diaphragm can be adsorbed on the top of the lower fixture by negative pressure, thereby preventing the diaphragm from bulging or deflecting during puncture; the vacuum mechanism is exemplarily selected from a micro diaphragm vacuum pump;

[0053] The pressing plate 422 slides up to the top, and the ball head of the ejector pin 3 has not yet applied force to the diaphragm 5. The lower positioning component is locked to connect the upper clamp 4 and the lower clamp 6 as a whole, and the upper positioning component is unlocked, so that the upper clamp 4 is separated from the ejector pin 3; when the pressing plate is completely pressed, the assembly of the upper clamp and the lower clamp has been completed, and the positioning process of the diaphragm has been completed. At this time, it is necessary to separate the lower positioning component and lock it first, and then unlock the upper positioning component, so that the ejector pin will not be subjected to the reverse force from the upper clamp when it continues to move downward, thereby ensuring the puncture accuracy; if the positioning strip and the socket are engaged, the worker can press the corresponding unlocking card head, and if it is an electromagnetic adsorption method, the corresponding control power button can be pressed;

[0054] S3, puncture test;

[0055] The ejector pin 3 applies force to puncture the diaphragm 5;

[0056] After the puncture action is completed, the ejector pin 3 is separated from the lower clamp 6. When the ejector pin 3 moves to the position of the top surface of the diaphragm, the lower positioning component is unlocked and the upper positioning component is locked;

[0057] The ejector pin 3 drives the upper fixture 4 to move upward, and the upper fixture 4 is separated from the lower fixture 6. The above method is used to conduct three verification tests, and the following data are obtained;

[0058]

[0059]

[0060] From the above data, we can see that the tensile strengths obtained from the three tests are almost the same. Through the improved diaphragm positioning method, the reliability and detection accuracy of the data have been greatly improved, and there will be no large fluctuations in the data.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A puncture device for testing the puncture strength of a lithium battery diaphragm, characterized in that: The detection bracket (1) comprises an upper base (11), a guide rod (12) and a lower base (13); the surface of the lower base (13) is vertically provided with a guide rod (12); the upper base (11) is provided at the top of the guide rod (12); a slide seat (2) is slidably mounted on the outer wall of the guide rod (12); a top pin (3) is vertically mounted at the center of the bottom surface of the slide seat (2); an upper clamp (4) is detachably mounted on the outer wall of the bottom end of the top pin (3); the upper clamp (4) is detachably mounted on the outer wall of the bottom end of the top pin (3); A lower fixture (6) is installed at the bottom of the tool (4), a diaphragm (5) having the same outer diameter as the upper fixture (4) is provided at the top of the lower fixture (6), the diaphragm (5) being embedded in the upper fixture (4), the interior of the lower fixture (6) being provided with air guide holes (61) distributed in a circular array, the top openings of the air guide holes (61) being located at the bottom of the diaphragm (5), the bottom openings of the air guide holes (61) being connected to a vacuum mechanism (7), the vacuum mechanism (7) being used to negatively pressure adsorb the diaphragm (5); The upper clamp (4) comprises a ring plate portion and a top plate portion, the top of the ring plate portion is provided with a top plate portion, the inner wall of the ring plate portion is provided with a clamping assembly, the clamping assembly is used to press the diaphragm (5) from the top down, the bottom of the ring plate portion is provided with a lower positioning assembly, the center of the top plate portion is provided with an opening (41) for the ejector pin to pass through, the interior of the opening (41) is provided with an upper positioning assembly, the upper positioning assembly and the lower positioning assembly are alternately locked; the upper positioning assembly is used to fix the upper clamp (4) and the ejector pin (3) as a whole, and the lower positioning assembly is used to fix the upper clamp (4) and the lower clamp (6) as a whole; The clamping assembly comprises a pressing plate (422) and a spring (421); the inner wall of the ring plate portion is provided with sliding grooves (42) distributed in an annular array; the inside of the sliding groove (42) is slidably mounted with a pressing plate (422); the bottom of the pressing plate (422) is provided with a spring (421), and the spring (421) is embedded in the sliding groove (42); The upper positioning component comprises a first positioning strip (411) and a first socket (31); the inner wall of the opening (41) is provided with first positioning strips (411) distributed in a ring array; the first socket (31) is provided at the bottom end of the ejector pin (3); the first positioning strip (411) is inserted into the first socket (31) from the top; the side section of the first positioning strip (411) is in the shape of a figure 7; the first positioning strip (411) and the first socket (31) are positioned by snap-fitting or magnetic adsorption.

2. A puncture device for testing the puncture strength of a lithium battery diaphragm according to claim 1, characterized in that: The bottom end of the ejector pin (3) is a hemispherical structure, and the first socket (31) is located on the top of the hemispherical structure.

3. A puncture device for testing the puncture strength of a lithium battery diaphragm according to claim 1, characterized in that: The lower positioning assembly comprises a second positioning strip (433) and a second socket (62); the second positioning strip (433) is arranged in a ring array on the bottom surface of the ring plate portion; the second socket (62) is arranged on the outer wall of the lower clamp (6); the second positioning strip (433) is inserted into the interior of the second socket (62); the second positioning strip (433) and the second socket (62) are positioned by snap-fitting or magnetic adsorption.

4. A puncture method for testing the puncture strength of a lithium battery separator, characterized in that: Using the puncture device described in claim 1, the puncture method comprises the following steps: S1. Place the diaphragm to be tested; Cut the diaphragm sample according to the outer diameter of the fixture; Place the diaphragm sample on the top of the lower fixture; Set test parameters; S2, compress the diaphragm; The ejector pin (3) moves downward, thereby driving the upper clamp (4) on the outer wall at its bottom end to move downward; The pressing plate (422) is attached to the top surface of the diaphragm sample. The pressing plate (422) is forced to slide upward along the slide groove (42) and compress the spring (421). At the same time, the pressing plate (422) presses down the diaphragm sample to eliminate the gap between the diaphragm sample and the lower clamp (6); During the upward sliding process of the pressing plate (422), the vacuum mechanism (7) is activated, the vacuum mechanism (7) extracts the air in the air guide hole (61), and the diaphragm sample is fixed to the top of the lower fixture (6) by negative pressure; The pressure plate (422) slides up to the top, and the ball head of the ejector pin (3) has not yet applied force to the diaphragm (5). The lower positioning assembly is locked to connect the upper clamp (4) and the lower clamp (6) as a whole, and the upper positioning assembly is unlocked to separate the upper clamp (4) from the ejector pin (3). S3, puncture test; The ejector pin (3) slides downward at a constant speed according to the set parameters until the diaphragm (5) is pierced; After the puncture action is completed, the ejector pin (3) is separated from the lower clamp (6), and when the ejector pin (3) moves to a position aligned with the top surface of the diaphragm, the lower positioning assembly is unlocked and the upper positioning assembly is locked; The ejector pin (3) drives the upper clamp (4) to move upward together, and the upper clamp (4) is separated from the lower clamp (6).

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