Cylindrical battery pole piece expansion force testing device and method

Abstract

The present application provides a device and method for testing the expansion force of cylindrical battery pole pieces. The above-mentioned cylindrical battery pole piece expansion force testing device includes a battery cell, a cylindrical hard shell, a thin film pressure sensing structure, a positive electrode line and a negative electrode line. The cylindrical hard shell includes a cylinder, a cover and an insulator, and the insulator is wound around the outer circumference of the cover. The thin film pressure sensing structure is arranged in the cylinder and immersed in the electrolyte, and the thin film pressure sensing structure is respectively relatively abutted against the inner wall of the cylinder and the outer wall of the battery cell. One end of the positive electrode line and one end of the negative electrode line are both electrically connected to the thin film pressure sensing structure, and the other end of the positive electrode line and the other end of the negative electrode line both protrude outside the cylinder. Part of the positive electrode line is clamped between the insulator and the cylinder, and part of the negative electrode line is clamped between the insulator and the cylinder. The above-mentioned cylindrical battery pole piece expansion force testing device can improve the accuracy and timeliness of the expansion force test of the battery cell, is simple and easy to operate, and the structure of the battery cell will not be damaged.

Description

Technical Field

[0001] The present invention relates to the technical field of battery testing, and in particular to a device and method for testing the expansion force of a cylindrical battery pole piece. Background Art

[0002] Lithium-ion batteries generate heat and accumulate stress during the charging and discharging process, both of which affect battery performance. Therefore, in battery testing projects, expansion force and temperature rise during the charging and discharging process are extremely critical indicators. Among them, excessive expansion force of single cells can cause fatigue failure of the battery module frame after long-term use, which will directly affect the reliability and safety of the entire battery system. Therefore, the detection of expansion force during battery charging and discharging will also provide important reference significance for the setting of battery module frame preload.

[0003] At present, the research equipment for battery expansion force is mostly applicable to multi-layer, large-capacity soft-pack batteries (Wei Z, Zhao J, He H, et al. Future smart battery and management: Advanced sensing from external to embedded multi-dimensional measurement [J]. Journal of Power Sources, 2021, 489: 229462.). The above-mentioned equipment converts the thickness directional change of the soft-pack battery into force or displacement information of the sensor through an external mechanical fixture, and then feeds back the expansion force evolution law of the battery during the charging and discharging process, such as the Chinese invention patent application with application number 202111200863.X. However, unlike the aluminum-plastic film shell of the soft-pack battery, the shell of the cylindrical battery uses stainless steel or hard aluminum shell. The high strength characteristics of the cylindrical shell make it difficult for the expansion force inside the battery to be transmitted to the outside. In view of the above reasons, the research on the expansion force of conventional soft-pack batteries is difficult to apply to batteries with cylindrical batteries as the target.

[0004] In summary, there is currently no simple, easy-to-operate, and non-destructive cylindrical battery electrode expansion force testing device. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a cylindrical battery electrode expansion force testing device and method that can improve the accuracy and timeliness of the expansion force test of the battery cell, is simple and easy to operate, and will not damage the structure of the battery cell.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] A cylindrical battery pole piece expansion force testing device, comprising a battery cell and a cylindrical hard shell, wherein the cylindrical hard shell comprises a cylinder, a cover and an insulator, wherein the cylinder is filled with an electrolyte, the battery cell is built into the cylinder and immersed in the electrolyte, the cover is arranged on the cylinder, the insulator is arranged around the outer circumference of the cover, and the insulator is sandwiched between the cylinder and the cover, the cylindrical battery pole piece expansion force testing device further comprises a thin film pressure sensing structure, a positive electrode line and a negative electrode line, the thin film pressure sensing structure A membrane-type pressure sensing structure is arranged in the cylinder and immersed in the electrolyte, and the membrane-type pressure sensing structure is respectively relatively abutted against the inner wall of the cylinder and the outer wall of the battery cell, one end of the positive wire and one end of the negative wire are both electrically connected to the membrane-type pressure sensing structure, and the other end of the positive wire and the other end of the negative wire both protrude outside the cylinder, part of the positive wire is clamped between the insulator and the cylinder, and part of the negative wire is clamped between the insulator and the cylinder.

[0008] In one embodiment, the thin film pressure sensing structure includes a first corrosion-resistant insulating layer, a second corrosion-resistant insulating layer and a thin film pressure sensor, the periphery of the first corrosion-resistant insulating layer and the periphery of the second corrosion-resistant insulating layer are connected to form a built-in cavity, the thin film pressure sensor is arranged in the built-in cavity, and the thin film pressure sensor is respectively abutted against the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer, the positive wire portion is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and is electrically connected to the thin film pressure sensor, and the negative wire portion is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and is electrically connected to the thin film pressure sensor.

[0009] In one embodiment, the first corrosion-resistant insulating layer is a PE film, a PET film, a PC film or an aluminum-plastic film.

[0010] In one embodiment, the second corrosion-resistant insulating layer is a PE film, a PET film, a PC film or an aluminum-plastic film.

[0011] In one embodiment, the thickness of the first corrosion-resistant insulating layer is 10 μm to 100 μm.

[0012] In one embodiment, the thickness of the second corrosion-resistant insulating layer is 10 μm to 100 μm.

[0013] In one embodiment, the thin film pressure sensing structure further includes a corrosion-resistant sealing strip, and the first corrosion-resistant insulating layer is tightly connected to the thin film pressure sensor and the second corrosion-resistant insulating layer respectively through the corrosion-resistant sealing strip.

[0014] In one embodiment, the thin film pressure sensor includes a pressure sensing body, two lead-out interfaces and two insulating protective covers. The pressure sensing body, the two lead-out interfaces and the two insulating protective covers are all arranged in the built-in cavity. The pressure sensing body is respectively in contact with the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer. The two insulating protective covers are both sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer. The two lead-out interfaces are both sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer. The pressure sensing body is electrically connected to the two lead-out interfaces respectively. One end of the positive wire is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and electrically connected to one of the lead-out interfaces. One end of the negative wire is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and electrically connected to the other lead-out interface. One of the insulating protective covers is sleeved on the connection between the positive wire and the corresponding lead-out interface, and the other insulating protective cover is sleeved on the connection between the negative wire and the corresponding lead-out interface.

[0015] In one embodiment, the positive electrode wire is a positive electrode micron enameled copper wire.

[0016] In one embodiment, the negative electrode wire is a negative electrode micron enameled copper wire.

[0017] In one embodiment, the diameter of the positive electrode wire is 20 μm to 100 μm.

[0018] In one embodiment, the diameter of the negative electrode wire is 20 μm to 100 μm.

[0019] In one embodiment, the thin film pressure sensing structure is a circular thin film pressure sensing structure with a diameter of 0.5 cm to 1 cm or a square thin film pressure sensing structure with a side length of 0.5 cm to 1 cm.

[0020] In one embodiment, an explosion-proof plate is provided on the cover body, the explosion-proof plate is stacked with the cover body, and the explosion-proof plate is wrapped around the outer circumference of the cover body, and the periphery of the explosion-proof plate is clamped between the insulator and the cover body.

[0021] A method for testing the expansion force of a cylindrical battery electrode comprises the following steps:

[0022] Obtain a thin film pressure sensor;

[0023] Performing a pressure resistance calibration operation on the thin film pressure sensor to obtain a curve showing the change of resistance of the thin film pressure sensor with pressure;

[0024] Performing a cylindrical battery preparation operation on the thin film pressure sensor to obtain the cylindrical battery pole piece expansion force testing device described in any of the above embodiments;

[0025] Performing an internal resistance monitoring operation on the cylindrical battery pole piece expansion force testing device to obtain a real-time internal resistance between the positive electrode line and the negative electrode line outside the cylinder;

[0026] The real-time internal resistance is compared with the curve of the resistance changing with pressure to obtain the expansion force of the cylindrical battery electrode.

[0027] In one embodiment, the cylindrical battery preparation operation for the thin film pressure sensor specifically includes the following steps:

[0028] Performing a positive and negative lead connection operation on the thin film pressure sensor so that the positive and negative electrodes of the thin film pressure sensor are electrically connected to a positive line and a negative line respectively;

[0029] Placing the thin film pressure sensor and the battery cell together in a cylinder so that the thin film pressure sensor is in contact with the inner wall of the cylinder and the outer wall of the battery cell respectively;

[0030] The cylinder is subjected to a liquid injection and sealing operation so that one end of the positive electrode wire and one end of the negative electrode wire are located outside the cylinder.

[0031] In one embodiment, before the step of placing the thin film pressure sensor in a cylinder for placement operation and after the step of performing positive and negative lead connection operation on the thin film pressure sensor, the following step is also included: performing a corrosion-resistant operation on the thin film pressure sensor so that the outer periphery of the thin film pressure sensor is covered with a corrosion-resistant insulating layer, the corrosion-resistant insulating layer includes a first corrosion-resistant insulating layer and a second corrosion-resistant insulating layer, the periphery of the first corrosion-resistant insulating layer and the periphery of the second corrosion-resistant insulating layer are connected to form a built-in cavity, the thin film pressure sensor is arranged in the built-in cavity, and the thin film pressure sensor is respectively abutted against the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer, the positive wire portion is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and is electrically connected to the thin film pressure sensor, and the negative wire portion is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and is electrically connected to the thin film pressure sensor.

[0032] Compared with the prior art, the present invention has at least the following advantages:

[0033] The cylindrical battery pole piece expansion force testing device of the present invention enables the thin film pressure sensing structure to be arranged in the cylinder and immersed in the electrolyte, and the thin film pressure sensing structure is respectively relatively abutted against the inner wall of the cylinder and the outer wall of the battery cell, that is, the thin film pressure sensing structure is clamped on the inner wall of the cylinder and the outer wall of the battery cell, thereby causing the thin film pressure sensing structure to be subjected to a certain compressive stress, and the pressure is obtained according to the pressure and resistance curve of the thin film pressure sensing structure, thereby alleviating the problem that the expansion force inside the battery is difficult to transmit to the outside and the expansion force test value is inaccurate, that is, better ensuring the accuracy of the real-time test value of the cylindrical battery pole piece expansion force test, and further making one end of the positive electrode line and one end of the negative electrode line electrically connected to the thin film pressure sensing structure, and the other end of the positive electrode line is electrically connected to the thin film pressure sensing structure, and the other end of the positive electrode line is electrically connected to the thin film pressure sensing structure. One end and the other end of the negative electrode wire protrude from the cylinder, that is, the positive electrode wire and the negative electrode wire are led out to measure the resistance of the thin film pressure sensing structure, thereby better realizing the acquisition of the pressure of the thin film pressure sensing structure, thereby better realizing the acquisition of real-time data of the expansion force of the cylindrical battery electrode piece through the pressure conversion of the thin film pressure sensing structure. It is simple and easy to operate, and part of the positive electrode wire and part of the negative electrode wire are clamped between the insulator and the cylinder, which better ensures the internal sealing of the cylindrical battery and the lead-out sealing of the positive electrode wire and the negative electrode wire, thereby making the structure of the cylindrical battery stable and not damaged in the process of realizing the expansion force test of the cylindrical battery electrode piece, and better realizing the non-destructive design of the structure of the cylindrical battery electrode piece expansion force testing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of the structure of a cylindrical battery pole piece expansion force testing device according to one embodiment of the present invention;

[0036] Figure 2 for Figure 1 A partial view of the cylindrical battery pole piece expansion force testing device shown;

[0037] Figure 3 for Figure 1 Another partial view of the cylindrical battery pole piece expansion force testing device shown;

[0038] Figure 4 for Figure 1 Another structural schematic diagram of the cylindrical battery pole piece expansion force testing device shown;

[0039] Figure 5 for Figure 4 A partial view of the cylindrical battery pole piece expansion force testing device shown;

[0040] Figure 6 for Figure 5 A cross-sectional view of the cylindrical battery pole piece expansion force testing device shown;

[0041] Figure 7 The present invention is a flow chart of a method for testing the expansion force of a cylindrical battery electrode according to one embodiment. DETAILED DESCRIPTION

[0042] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0043] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] The present application provides a device for testing the expansion force of cylindrical battery pole pieces. The device comprises a battery cell, a cylindrical hard shell, a thin-film pressure sensing structure, a positive electrode wire, and a negative electrode wire. The cylindrical hard shell comprises a cylindrical body, a cover, and an insulator. The cylinder is filled with electrolyte, the battery cell is embedded in the cylinder and immersed in the electrolyte, the cover is disposed on the cylinder, and the insulator is wound around the outer circumference of the cover and sandwiched between the cylinder and the cover. The thin-film pressure sensing structure is disposed within the cylinder and immersed in the electrolyte, and the thin-film pressure sensing structure abuts the inner wall of the cylinder and the outer wall of the battery cell, respectively. One end of the positive electrode wire and one end of the negative electrode wire are both electrically connected to the thin-film pressure sensing structure, and the other ends of the positive electrode wire and the other ends of the negative electrode wire protrude outside the cylinder. A portion of the positive electrode wire is sandwiched between the insulator and the cylinder, and a portion of the negative electrode wire is sandwiched between the insulator and the cylinder.

[0046] The above-mentioned cylindrical battery pole piece expansion force testing device enables the thin film pressure sensing structure to be arranged in the cylinder and immersed in the electrolyte, and the thin film pressure sensing structure is respectively relatively abutted against the inner wall of the cylinder and the outer wall of the battery cell, that is, the thin film pressure sensing structure is clamped on the inner wall of the cylinder and the outer wall of the battery cell, thereby causing the thin film pressure sensing structure to be subjected to a certain compressive stress, and the pressure is obtained according to the pressure and resistance curve of the thin film pressure sensing structure, thereby alleviating the problem that the expansion force inside the battery is difficult to transmit to the outside and the expansion force test value is inaccurate, that is, better ensuring the accuracy of the real-time test value of the cylindrical battery pole piece expansion force test, and further making one end of the positive electrode line and one end of the negative electrode line electrically connected to the thin film pressure sensing structure, and the other end of the positive electrode line is electrically connected to the thin film pressure sensing structure, and the other end of the positive electrode line is electrically connected to the thin film pressure sensing structure. The positive electrode line and the other end of the negative electrode line protrude from the cylinder, that is, the positive electrode line and the negative electrode line are led out to measure the resistance of the thin film pressure sensing structure, thereby better realizing the acquisition of the pressure of the thin film pressure sensing structure, thereby better realizing the acquisition of real-time data of the expansion force of the cylindrical battery pole piece through the pressure conversion of the thin film pressure sensing structure. It is simple and easy to operate, and part of the positive electrode line and part of the negative electrode line are clamped between the insulator and the cylinder, which better ensures the internal sealing of the cylindrical battery and the lead-out sealing of the positive electrode line and the negative electrode line, thereby making the structure of the cylindrical battery stable and not damaged in the process of realizing the expansion force test of the cylindrical battery pole piece, and better realizing the non-destructive design of the structure of the cylindrical battery pole piece expansion force testing device.

[0047] In order to better understand the cylindrical battery pole piece expansion force testing device of the present application, the cylindrical battery pole piece expansion force testing device of the present application is further explained below:

[0048] Please also refer to Figures 1 to 3A cylindrical battery electrode expansion force testing device 10 according to one embodiment includes a battery cell 100, a cylindrical hard shell 200, a thin film pressure sensing structure 300, a positive electrode cable 400, and a negative electrode cable 500. The cylindrical hard shell 200 includes a cylindrical body 210, a cover 220, and an insulator 230. The cylindrical body 210 is filled with an electrolyte, and the battery cell 100 is housed within the cylindrical body 210 and immersed in the electrolyte. The cover 220 is disposed on the cylindrical body 210, and the insulator 230 is disposed around the outer circumference of the cover 220 and sandwiched between the cylindrical body 210 and the cover 220. The thin film pressure sensing structure 300 is arranged in the cylinder 210 and immersed in the electrolyte, and the thin film pressure sensing structure 300 is respectively relatively abutted against the inner wall of the cylinder 210 and the outer wall of the battery cell 100. One end of the positive wire 400 and one end of the negative wire 500 are both electrically connected to the thin film pressure sensing structure 300, and the other end of the positive wire 400 and the other end of the negative wire 500 both protrude outside the cylinder 210. Part of the positive wire 400 is clamped between the insulator 230 and the cylinder 210, and part of the negative wire 500 is clamped between the insulator 230 and the cylinder 210.

[0049] The above-mentioned cylindrical battery pole piece expansion force testing device 10 enables the thin film pressure sensing structure 300 to be arranged in the cylinder 210 and immersed in the electrolyte, and the thin film pressure sensing structure 300 is respectively relatively abutted against the inner wall of the cylinder 210 and the outer wall of the battery cell 100, that is, the thin film pressure sensing structure 300 is clamped on the inner wall of the cylinder 210 and the outer wall of the battery cell 100, thereby causing the thin film pressure sensing structure 300 to be subjected to a certain compressive stress. The pressure is obtained according to the pressure and resistance curve of the thin film pressure sensing structure 300, which alleviates the problem that the expansion force inside the battery is difficult to transmit to the outside and the expansion force test value is inaccurate, that is, better ensures the accuracy of the real-time test value of the cylindrical battery pole piece expansion force test, and further enables one end of the positive line 400 and one end of the negative line 500 to be electrically connected to the thin film pressure sensing structure 300, and the positive line 400 is electrically connected to the thin film pressure sensing structure 300. The other end and the other end of the negative electrode line 500 protrude outside the cylinder 210, that is, the positive electrode line 400 and the negative electrode line 500 are led out to measure the resistance of the thin film pressure sensing structure 300, thereby better realizing the acquisition of the pressure of the thin film pressure sensing structure 300, thereby better realizing the acquisition of real-time data of the expansion force of the cylindrical battery pole piece through the pressure conversion of the thin film pressure sensing structure 300. It is simple and easy to operate, and part of the positive electrode line 400 and part of the negative electrode line 500 are clamped between the insulator 230 and the cylinder 210, which better ensures the internal sealing of the cylindrical battery and the lead-out sealing of the positive electrode line 400 and the negative electrode line 500, thereby making the structure of the cylindrical battery stable and not damaged in the process of realizing the cylindrical battery pole piece expansion force test, and better realizing the non-destructive design of the structure of the cylindrical battery pole piece expansion force testing device 10.

[0050] Please also refer to Figures 1 to 3In one embodiment, the thin film pressure sensing structure 300 includes a first corrosion-resistant insulating layer 310, a second corrosion-resistant insulating layer 320 and a thin film pressure sensor 330. The periphery of the first corrosion-resistant insulating layer 310 and the periphery of the second corrosion-resistant insulating layer 320 are connected to form an internal cavity 301. The thin film pressure sensor 330 is disposed in the internal cavity 301, and the thin film pressure sensor 330 is respectively in contact with the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320. The positive electrode line 400 is partially sandwiched between the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320 and is electrically connected to the thin film pressure sensor 330. The negative electrode line 500 is partially sandwiched between the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320 and is electrically connected to the thin film pressure sensor 330. It can be understood that the thin film pressure sensor 330 is arranged in the built-in cavity 301, and the thin film pressure sensor 330 is respectively abutted against the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320, so that the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320 can better achieve the operation and structural stability of the thin film pressure sensor 330, that is, better ensure the pressure sensing accuracy of the thin film pressure sensor 330 in the cylinder 210 and immersed in the electrolyte, that is, better make the real-time test results of the cylindrical battery pole piece expansion force test more accurate and reliable. In addition, the positive electrode line 400 and the negative electrode line 500 are partially sandwiched between the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320 and are both electrically connected to the thin film pressure sensor 330, that is, the connection between the positive electrode line 400 and the thin film pressure sensor 330, as well as the connection between the negative electrode line 500 and the thin film pressure sensor 330 are protected by the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320, thereby better ensuring the connection stability of the positive electrode line 400 and the negative electrode line 500 and the thin film pressure sensor 330 respectively, thereby better ensuring the stable real-time measurement of the resistance of the thin film pressure sensor 330, and further better ensuring the stability and effectiveness of the real-time test results of the cylindrical battery pole piece expansion force test.

[0051] In one embodiment, the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer are an integrally formed structure.

[0052] In one embodiment, the first corrosion-resistant insulating layer is a PE film, a PET film, a PC film, or an aluminum-plastic film. It is understood that the PE film is a polyethylene film; the PET film is a polyethylene terephthalate film; and the PC film is a polycarbonate film. The PE film, PET film, PC film, or aluminum-plastic film all have excellent corrosion resistance and insulation properties, thereby effectively ensuring the corrosion resistance and insulation properties of the first corrosion-resistant insulating layer when immersed in the electrolyte. This effectively protects the thin-film pressure sensor, thereby effectively ensuring the pressure sensing accuracy of the thin-film pressure sensor when embedded in a cylindrical body and immersed in the electrolyte. This ensures more accurate and reliable real-time test results of cylindrical battery electrode expansion force testing.

[0053] In one embodiment, the second corrosion-resistant insulating layer is a PE film, a PET film, a PC film, or an aluminum-plastic film. It is understood that a PE film is a polyethylene film; a PET film is a polyethylene terephthalate film; and a PC film is a polycarbonate film. PE, PET, PC, or aluminum-plastic films all have excellent corrosion resistance and insulation properties, thereby effectively ensuring the corrosion resistance and insulation properties of the second corrosion-resistant insulating layer when immersed in the electrolyte. This effectively protects the thin-film pressure sensor, thereby effectively ensuring the pressure sensing accuracy of the thin-film pressure sensor when embedded in a cylindrical body and immersed in the electrolyte. This ensures more accurate and reliable real-time test results of cylindrical battery electrode expansion force testing.

[0054] In one embodiment, the thickness of the first corrosion-resistant insulating layer is 10μm to 100μm, which can better achieve the protection effect of the thin film pressure sensor and reduce the occupation of the internal space of the cylinder, thereby better ensuring the battery capacity of the cylindrical battery and better making the real-time test results of the cylindrical battery pole piece expansion force test more accurate and reliable.

[0055] In one embodiment, the thickness of the second corrosion-resistant insulating layer is 10μm to 100μm, which can better achieve the protection effect of the thin film pressure sensor and reduce the occupation of the internal space of the cylinder, thereby better ensuring the battery capacity of the cylindrical battery and better making the real-time test results of the cylindrical battery pole piece expansion force test more accurate and reliable.

[0056] Please also refer to Figures 1 to 3In one embodiment, the thin film pressure sensing structure 300 further includes a corrosion-resistant sealing strip 340. The first corrosion-resistant insulating layer 310 is tightly connected to the thin film pressure sensor 330 and the second corrosion-resistant insulating layer 320 through the corrosion-resistant sealing strip 340, thereby effectively ensuring the sealing and covering effect of the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320 on the thin film pressure sensor 330. This further effectively ensures the pressure sensing accuracy of the thin film pressure sensor 330 when the thin film pressure sensor 330 is inside the cylinder 210 and immersed in the electrolyte. This makes the real-time test results of the cylindrical battery electrode expansion force test more accurate and reliable.

[0057] In one embodiment, the corrosion-resistant sealing tape is an acrylic tape.

[0058] Please also refer to Figures 1 to 3 In one embodiment, the thin film pressure sensor 330 includes a pressure sensing body 331, two lead-out interfaces 332 and two insulating protective sleeves 333. The pressure sensing body 331, the two lead-out interfaces 332 and the two insulating protective sleeves 333 are all arranged in the built-in cavity 301. The pressure sensing body 331 is respectively in contact with the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320. The two insulating protective sleeves 333 are both sandwiched between the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320. The two lead-out interfaces 332 are both sandwiched between the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320. The pressure sensing body 331 is respectively in contact with the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320. The two lead-out interfaces 332 are electrically connected, one end of the positive line 400 is clamped between the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320 and electrically connected to one of the lead-out interfaces 332, and one end of the negative line 500 is clamped between the first corrosion-resistant insulating layer 310 and the second corrosion-resistant insulating layer 320 and electrically connected to the other lead-out interface 332. One insulating protective cover 333 is sleeved on the connection between the positive line 400 and the corresponding lead-out interface 332, and the other insulating protective cover 333 is sleeved on the connection between the negative line 500 and the corresponding lead-out interface 332, thereby better realizing the electrical connection stability between the thin film pressure sensor 330 and the positive line 400 and the negative line 500 respectively.

[0059] In one embodiment, the positive electrode wire is a positive electrode micron enameled copper wire, which better ensures the operation and structural stability of the positive electrode wire and the cylinder when immersed in the electrolyte, thereby better ensuring the stable real-time measurement of the resistance of the thin film pressure sensor.

[0060] In one embodiment, the negative electrode wire is a negative electrode micron enameled copper wire, which better ensures the operation and structural stability of the positive electrode wire and the cylinder when immersed in the electrolyte, thereby better ensuring the stable real-time measurement of the resistance of the thin film pressure sensor.

[0061] In one embodiment, the diameter of the positive electrode wire is 20 μm to 100 μm.

[0062] In one embodiment, the diameter of the negative electrode wire is 20 μm to 100 μm.

[0063] In one embodiment, the thin film pressure sensing structure is a circular thin film pressure sensing structure with a diameter of 0.5 cm to 1 cm or a square thin film pressure sensing structure with a side length of 0.5 cm to 1 cm. It can be understood that by making the thin film pressure sensing structure a circular thin film pressure sensing structure with a diameter of 0.5 cm to 1 cm or a square thin film pressure sensing structure with a side length of 0.5 cm to 1 cm, the size of the circular thin film pressure sensing structure is smaller, and the contact area between the inner wall of the cylinder and the outer wall of the battery cell is approximately considered to be a flat surface, thereby making the pressure sensing of the thin film pressure sensor accurate and reliable, and better ensuring the accuracy and reliability of the real-time test results of the cylindrical battery electrode expansion force test.

[0064] Please also refer to Figures 3 to 6It can be understood that due to the small size of the thin film pressure sensing structure and its immersion in the electrolyte, when the cylindrical battery is moved, swung, or shaken, even if the thin film pressure sensing structure is clamped between the inner wall of the cylinder and the outer wall of the battery cell with a certain pressure, the thin film pressure sensing structure is used to further measure the change in the expansion force of the cylindrical battery electrode. As a result, the pressure on the thin film pressure sensing structure is limited, that is, the thin film pressure sensing structure cannot be subjected to a large pressure. As a result, the thin film pressure sensing structure is prone to movement under the repeated impact of the electrolyte, causing fluctuations in the pressure it is subjected to, affecting the accuracy and stability of the feedback structure of the cylindrical battery electrode expansion force fed back by the thin film pressure sensing structure. Therefore, in the present application, in order to better ensure the accuracy and reliability of the cylindrical battery electrode expansion force testing structure, in one embodiment, the thin film pressure sensing structure 300 further includes a suction cup 350. The suction cup 350 is arranged on the central axis of the thin film pressure sensor 330. The suction cup 350 is connected to the first corrosion-resistant insulating layer 310 or the second corrosion-resistant insulating layer 320. The central axis of the thin film pressure sensor 330 is in the same direction as the length of the cylinder. The thin film pressure sensor 330 is supported and fixed on the inner wall of the cylinder by the suction cup 350, that is, the suction cup 350 is used to achieve fixed contact between the thin film pressure sensor 330 and the inner wall of the cylinder. The suction cup 350 is arranged on the central axis of the thin film pressure sensor 330, so that the suction cup 350 can better fill and utilize the space of the fan-shaped vacant area formed with the inner wall of the cylinder, that is, while occupying less additional space of the cylinder, it further achieves that the inner wall formed by the cylinder and the suction cup 350 and the contact surface of the thin film pressure sensor is flat, further ensuring the accuracy and reliability of the cylindrical battery pole piece expansion force test structure, and better ensuring the battery capacity of the cylindrical battery.

[0065] It should be noted that if a clamping structure or an embedded structure is set to fix the thin film pressure sensor 330, the clamping structure and the front structure will cause the pressure sensing value of the thin film pressure sensor 330 to be inaccurate, that is, the clamping structure and the embedded structure will give the thin film pressure sensor 330 a certain pressure, so that when the electrolyte impacts the thin film pressure sensor 330, the thin film pressure sensor 330 will be mechanically interfered with by the clamping structure and the front structure, and the feedback pressure data will have fluctuations, making it difficult to achieve stable and reliable measurement of the thin film pressure sensor 330. In addition, if it is necessary to add an embedded structure and a clamping structure to fix the thin film pressure sensor 330, it needs to be processed and formed on the side wall of the cylinder. However, since the thickness of the cylinder itself is relatively thin, the embedded structure or clamping structure formed on the cylinder is actually difficult to achieve effective fixation of the thin film pressure sensor 330, and the processing difficulty is relatively high.

[0066] Please also refer to Figures 3 to 6 In one embodiment, the suction cup 350 includes a fixing portion 351, a vacuum transition portion 352 and an annular suction wing portion 353. The fixing portion 351 is embedded in the first corrosion-resistant insulating layer 310 or the second corrosion-resistant insulating layer 320, and the fixing portion 351 is connected to the vacuum transition portion 352. A vacuum hole is opened on the vacuum transition portion 352. The inner ring of the annular suction wing portion 353 is connected to the vacuum transition portion 352. The fixing portion 351 and the annular suction wing portion 353 are respectively located at both ends of the vacuum hole.

[0067] Please also refer to Figures 3 to 6 In one embodiment, the annular suction wing portion 353 includes a first annular suction wing body 3531 and a second annular suction wing body 3532, the inner ring of the first annular suction wing body 3531 is connected to the vacuum transition portion 352, the outer ring of the first annular suction wing body 3531 is connected to the inner ring of the second annular suction wing body 3532, the thickness of the first annular suction wing body 3531 gradually decreases in the direction from the inner ring to the outer ring, and the thickness of the second annular suction wing body 3532 gradually decreases in the direction from the inner ring to the outer ring.

[0068] In one embodiment, the thickness of the first annular suction wing decreases in the direction from the inner ring to the outer ring less than the thickness of the second annular suction wing decreases in the direction from the inner ring to the outer ring.

[0069] In one embodiment, the wall thickness of the vacuum hole of the vacuum transition portion gradually decreases in the direction from the fixing portion toward the first annular suction wing body.

[0070] In one embodiment, the outer periphery of the first annular suction wing has a thickness of 10 μm to 20 μm. Furthermore, the inner periphery of the first annular suction wing has a thickness of 20 μm to 50 μm. This effectively ensures the stability of the film-type pressure sensor body fixed to the inner wall of the cylinder by the suction cup, effectively reduces the space occupied by the suction cup, and effectively ensures that the film-type pressure sensor body is planarly aligned with the inner wall of the cylinder. This ensures the accuracy and reliability of the cylindrical battery pole piece expansion force test structure while also effectively ensuring the battery capacity of the cylindrical battery.

[0071] In one embodiment, the overall thickness of the suction cup is less than 150 μm. Preferably, the overall thickness of the suction cup is less than 100 μm, which further ensures the accuracy and reliability of the cylindrical battery pole piece expansion force test structure and better ensures the battery capacity of the cylindrical battery.

[0072] In one embodiment, the thickness of the outer ring edge of the first annular suction wing is 15 μm, and the thickness of the inner ring edge is 40 μm; the thickness of the outer ring edge of the second annular suction wing is 42 μm, and the thickness of the inner ring edge is 52 μm. The maximum thickness of the vacuum transition part is 90 μm, and the overall thickness is uniformly reduced to a minimum thickness of 52 μm.

[0073] In one embodiment, the suction cup is a silicone rubber suction cup, specifically, the suction cup is a Kraft 704RTV silicone rubber soft glue suction cup, which better ensures the structural stability of the suction cup in the electrolyte and better ensures the adsorption effect of the suction cup on the inner wall of the cylinder.

[0074] Please also refer to Figures 1 to 3 In one embodiment, an explosion-proof piece 240 is provided on the cover body 220. The explosion-proof piece 240 and the cover body 220 are stacked and arranged around the outer periphery of the cover body 220. The periphery of the explosion-proof piece 240 is clamped between the insulator 230 and the cover body 220, which better ensures the safety of the cylindrical battery.

[0075] It should be noted that the pressure sensing body is a thin film pressure sensor commonly used on the market. This application does not protect the structure of the pressure sensing body, but only protects the connection relationship and position relationship of the pressure sensing body.

[0076] The present application also provides a method for testing the expansion force of a cylindrical battery electrode. The aforementioned method comprises the following steps: obtaining a thin-film pressure sensor; performing a pressure resistance calibration operation on the thin-film pressure sensor to plot a curve showing the resistance of the thin-film pressure sensor as a function of pressure; performing a cylindrical battery preparation operation on the thin-film pressure sensor to obtain a cylindrical battery electrode expansion force testing device according to any of the aforementioned embodiments; performing an internal resistance monitoring operation on the cylindrical battery electrode expansion force testing device to obtain the real-time internal resistance between the positive and negative electrodes outside the cylinder; and comparing the real-time internal resistance with the curve showing the resistance as a function of pressure to obtain the expansion force of the cylindrical battery electrode.

[0077] The above-mentioned method for testing the expansion force of cylindrical battery pole pieces uses a thin film pressure sensor built into the cylindrical battery, that is, the thin film pressure sensor in the cylindrical battery pole piece expansion force testing device is arranged inside the cylinder and immersed in the electrolyte, so that the pressure is obtained according to the pressure and resistance curve of the thin film pressure sensor, thereby alleviating the problem that the expansion force inside the battery is difficult to transmit to the outside and the expansion force test value is inaccurate, and by measuring the real-time internal resistance between the positive line and the negative line, that is, measuring the internal resistance of the thin film pressure sensor, further based on the internal resistance of the thin film pressure sensor, further comparing the curve of the resistance of the thin film pressure sensor with the pressure change to obtain the data of the expansion force of the cylindrical battery pole piece, thereby realizing accurate and effective measurement of the expansion force of the cylindrical battery pole piece.

[0078] In order to better understand the cylindrical battery pole piece expansion force testing method of the present application, the cylindrical battery pole piece expansion force testing method of the present application is further explained below:

[0079] See also Figure 7 A method for testing the expansion force of a cylindrical battery electrode sheet according to one embodiment includes the following steps:

[0080] S100: Obtain a thin film pressure sensor. It is understood that the thin film pressure sensor has a good pressure sensing effect, that is, it can better ensure the measurement effect of the expansion force of the pole piece of the cylindrical battery.

[0081] S200: Perform a pressure resistance calibration operation on the thin-film pressure sensor and plot a curve showing the resistance of the thin-film pressure sensor as a function of pressure. It will be appreciated that using a standard load cell to perform a pressure resistance calibration operation on the thin-film pressure sensor and plotting the resulting curve showing the resistance of the thin-film pressure sensor as a function of pressure effectively ensures the accuracy of the correspondence between the value fed back by the thin-film pressure sensor and the expansion force of the cylindrical battery electrode, thereby effectively ensuring the accuracy and reliability of the test structure for the expansion force of the cylindrical battery electrode.

[0082] S300: Performing a cylindrical battery preparation operation on the thin-film pressure sensor to obtain a cylindrical battery electrode sheet expansion force testing device according to any of the above-described embodiments. It can be understood that in the cylindrical battery electrode sheet expansion force testing device, the thin-film pressure sensor is disposed within the cylinder and immersed in the electrolyte. Pressure is acquired based on the pressure and resistance curve of the thin-film pressure sensor, alleviating the problem of inaccurate expansion force test values ​​resulting from the difficulty in transmitting internal battery expansion force to the outside. This effectively ensures the accuracy of real-time test values ​​for cylindrical battery electrode sheet expansion force testing. Furthermore, one end of the positive and negative electrodes are both electrically connected to the thin-film pressure sensor, and the other ends of the positive and negative electrodes protrude from the cylinder. This allows the positive and negative electrodes to be led out for resistance measurement of the thin-film pressure sensor. This effectively acquires pressure from the thin-film pressure sensor, thereby effectively acquiring real-time data on the cylindrical battery electrode sheet expansion force through pressure conversion using the thin-film pressure sensor, resulting in simple and easy operation.

[0083] S400: Perform internal resistance monitoring on the cylindrical battery electrode sheet expansion force testing device to obtain real-time internal resistance between the positive and negative electrode wires outside the cylinder. It will be appreciated that measuring the real-time internal resistance between the positive and negative electrode wires, i.e., obtaining the internal resistance of the thin film pressure sensor, facilitates subsequent conversion of real-time data on the cylindrical battery electrode sheet expansion force based on the internal resistance of the thin film pressure sensor.

[0084] S500: Compare the real-time internal resistance with the curve showing changes in resistance versus pressure to obtain the expansion force of the cylindrical battery electrode. It is understood that by comparing the internal resistance of the thin-film pressure sensor with the curve showing changes in resistance versus pressure to obtain data on the expansion force of the cylindrical battery electrode, the expansion force of the cylindrical battery electrode can be measured.

[0085] The above-mentioned method for testing the expansion force of cylindrical battery pole pieces uses a thin film pressure sensor built into the cylindrical battery, that is, the thin film pressure sensor in the cylindrical battery pole piece expansion force testing device is arranged inside the cylinder and immersed in the electrolyte, so that the pressure is obtained according to the pressure and resistance curve of the thin film pressure sensor, thereby alleviating the problem that the expansion force inside the battery is difficult to transmit to the outside and the expansion force test value is inaccurate, and by measuring the real-time internal resistance between the positive line and the negative line, that is, measuring the internal resistance of the thin film pressure sensor, further based on the internal resistance of the thin film pressure sensor, further comparing the curve of the resistance of the thin film pressure sensor with the pressure change to obtain the data of the expansion force of the cylindrical battery pole piece, thereby realizing accurate and effective measurement of the expansion force of the cylindrical battery pole piece.

[0086] In one embodiment, a cylindrical battery preparation operation is performed on a thin film pressure sensor, specifically comprising the following steps:

[0087] Performing a positive and negative lead connection operation on the thin film pressure sensor so that the positive and negative electrodes of the thin film pressure sensor are electrically connected to the positive electrode wire and the negative electrode wire respectively;

[0088] Place the thin film pressure sensor and the battery cell together in the cylinder so that the thin film pressure sensor is in contact with the inner wall of the cylinder and the outer wall of the battery cell respectively;

[0089] The cylinder is sealed by injecting liquid so that one end of the positive electrode wire and one end of the negative electrode wire are located outside the cylinder.

[0090] It can be understood that the arrangement of the thin film pressure sensor within the cylinder is better realized, and the sealed and insulated lead-out of the positive and negative lines is better realized, that is, the acquisition of the pressure of the thin film pressure sensor is better ensured, which is conducive to obtaining real-time data on the expansion force of the cylindrical battery electrode through pressure conversion of the thin film pressure sensor, which is simple and easy to operate.

[0091] In one embodiment, before the step of placing the thin film pressure sensor in the cylinder for placement operation and after the step of connecting the positive and negative leads of the thin film pressure sensor, the following steps are also included: performing a corrosion-resistant operation on the thin film pressure sensor so that the outer periphery of the thin film pressure sensor is covered with a corrosion-resistant insulating layer, the corrosion-resistant insulating layer includes a first corrosion-resistant insulating layer and a second corrosion-resistant insulating layer, the periphery of the first corrosion-resistant insulating layer and the periphery of the second corrosion-resistant insulating layer are connected to form a built-in cavity, the thin film pressure sensor is arranged in the built-in cavity, and the thin film pressure sensor is respectively abutted against the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer, the positive electrode line is clamped between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and are both electrically connected to the thin film pressure sensor, and the negative electrode line portion is clamped between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and is electrically connected to the thin film pressure sensor.

[0092] Compared with the prior art, the present invention has at least the following advantages:

[0093] The cylindrical battery pole piece expansion force testing device 10 of the present invention enables the thin film pressure sensing structure 300 to be arranged in the cylinder 210 and immersed in the electrolyte, and the thin film pressure sensing structure 300 is respectively relatively abutted against the inner wall of the cylinder 210 and the outer wall of the battery cell 100, that is, the thin film pressure sensing structure 300 is clamped on the inner wall of the cylinder 210 and the outer wall of the battery cell 100, thereby causing the thin film pressure sensing structure 300 to be subjected to a certain compressive stress. The pressure is obtained according to the pressure and resistance curve of the thin film pressure sensing structure 300, thereby alleviating the problem that the expansion force inside the battery is difficult to transmit to the outside and the expansion force test value is inaccurate, that is, better ensuring the accuracy of the real-time test value of the cylindrical battery pole piece expansion force test, and further making one end of the positive line 400 and one end of the negative line 500 both electrically connected to the thin film pressure sensing structure 300, and the positive line 400 The other end and the other end of the negative electrode line 500 protrude outside the cylinder 210, that is, the positive electrode line 400 and the negative electrode line 500 are led out to measure the resistance of the thin film pressure sensing structure 300, thereby better realizing the acquisition of the pressure of the thin film pressure sensing structure 300, thereby better realizing the acquisition of real-time data of the expansion force of the cylindrical battery pole piece through the pressure conversion of the thin film pressure sensing structure 300. It is simple and easy to operate, and part of the positive electrode line 400 and part of the negative electrode line 500 are clamped between the insulator 230 and the cylinder 210, which better ensures the internal sealing of the cylindrical battery and the lead-out sealing of the positive electrode line 400 and the negative electrode line 500, thereby making the structure of the cylindrical battery stable and not damaged in the process of realizing the cylindrical battery pole piece expansion force test, and better realizing the non-destructive design of the structure of the cylindrical battery pole piece expansion force testing device 10.

[0094] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A cylindrical battery pole piece expansion force testing device, comprising a battery cell and a cylindrical hard shell, wherein the cylindrical hard shell comprises a cylinder, a cover, and an insulator, wherein the cylinder is filled with an electrolyte, the battery cell is built into the cylinder and immersed in the electrolyte, the cover is disposed on the cylinder, the insulator is disposed around the outer circumference of the cover, and the insulator is sandwiched between the cylinder and the cover, characterized in that: The cylindrical battery pole piece expansion force testing device further includes a thin film pressure sensing structure, a positive electrode wire, and a negative electrode wire. The thin film pressure sensing structure is disposed within the cylinder and immersed in the electrolyte, and the thin film pressure sensing structure is relatively abutted against the inner wall of the cylinder and the outer wall of the battery cell, respectively. One end of the positive electrode wire and one end of the negative electrode wire are both electrically connected to the thin film pressure sensing structure, and the other ends of the positive electrode wire and the other ends of the negative electrode wire protrude outside the cylinder. Part of the positive electrode wire is sandwiched between the insulator and the cylinder, and part of the negative electrode wire is sandwiched between the insulator and the cylinder. The thin film pressure sensing structure includes a first corrosion-resistant insulating layer, a second corrosion-resistant insulating layer, and a thin film pressure sensor. The periphery of the first corrosion-resistant insulating layer and the periphery of the second corrosion-resistant insulating layer are connected to form a built-in cavity. The thin film pressure sensor is disposed in the built-in cavity and abuts against the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer, respectively. The positive wire portion is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and is electrically connected to the thin film pressure sensor. The negative wire portion is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and is electrically connected to the thin film pressure sensor. The thin film pressure sensing structure further includes a suction cup, which is disposed on the central axis of the thin film pressure sensor and is connected to the first corrosion-resistant insulating layer or the second corrosion-resistant insulating layer. The central axis of the thin film pressure sensor is in the same direction as the length of the cylinder. The thin film pressure sensor is supported and fixed on the inner wall of the cylinder by the suction cup, and the suction cup is disposed on the central axis of the thin film pressure sensor. The suction cup is a silicone rubber suction cup; The suction cup includes a fixing portion, a vacuum transition portion, and an annular suction wing portion. The fixing portion is embedded in the first corrosion-resistant insulating layer or the second corrosion-resistant insulating layer and connected to the vacuum transition portion. A vacuum hole is formed on the vacuum transition portion. The inner ring of the annular suction wing portion is connected to the vacuum transition portion. The fixing portion and the annular suction wing portion are respectively located at both ends of the vacuum hole. The annular suction wing portion includes a first annular suction wing body and a second annular suction wing body, the inner ring of the first annular suction wing body is connected to the vacuum transition portion, the outer ring of the first annular suction wing body is connected to the inner ring of the second annular suction wing body, the thickness of the first annular suction wing body gradually decreases in the direction from the inner ring to the outer ring, and the thickness of the second annular suction wing body gradually decreases in the direction from the inner ring to the outer ring; The thickness of the first annular suction wing decreases in the direction from the inner ring to the outer ring less than the thickness of the second annular suction wing decreases in the direction from the inner ring to the outer ring; The hole wall thickness of the vacuum hole of the vacuum transition portion gradually decreases in the direction from the fixing portion toward the first annular suction wing body.

2. The cylindrical battery pole piece expansion force testing device according to claim 1, characterized in that: The first corrosion-resistant insulating layer is a PE film, a PET film, a PC film or an aluminum-plastic film; and / or, The second corrosion-resistant insulating layer is a PE film, a PET film, a PC film or an aluminum-plastic film; and / or, The thickness of the first corrosion-resistant insulating layer is 10 μm to 100 μm; and / or, The thickness of the second corrosion-resistant insulating layer is 10 μm to 100 μm.

3. The cylindrical battery pole piece expansion force testing device according to claim 1, characterized in that: The thin film pressure sensing structure further includes a corrosion-resistant sealing strip, through which the first corrosion-resistant insulating layer is tightly connected to the thin film pressure sensor and the second corrosion-resistant insulating layer.

4. The cylindrical battery pole piece expansion force testing device according to claim 1, characterized in that: The thin film pressure sensor includes a pressure sensing body, two lead-out interfaces, and two insulating protective sleeves. The pressure sensing body, the two lead-out interfaces, and the two insulating protective sleeves are all arranged in the built-in cavity. The pressure sensing body is respectively in contact with the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer. The two insulating protective sleeves are both sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer. The two lead-out interfaces are both sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer. The pressure sensing body is electrically connected to the two lead-out interfaces, respectively. One end of the positive wire is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and electrically connected to one of the lead-out interfaces. One end of the negative wire is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and electrically connected to the other lead-out interface. One insulating protective sleeve is sleeved on the connection between the positive wire and the corresponding lead-out interface, and the other insulating protective sleeve is sleeved on the connection between the negative wire and the corresponding lead-out interface.

5. The cylindrical battery pole piece expansion force testing device according to claim 1, characterized in that: The positive electrode wire is a positive electrode micron enameled copper wire; and / or, The negative electrode wire is a negative electrode micron enameled copper wire; and / or, The diameter of the positive electrode wire is 20 μm to 100 μm; and / or, The diameter of the negative electrode wire is 20 μm to 100 μm; and / or, The thin film pressure sensing structure is a circular thin film pressure sensing structure with a diameter of 0.5 cm to 1 cm or a square thin film pressure sensing structure with a side length of 0.5 cm to 1 cm.

6. The cylindrical battery pole piece expansion force testing device according to claim 1, characterized in that: The cover body is provided with an explosion-proof plate, which is stacked with the cover body and wound around the outer periphery of the cover body. The periphery of the explosion-proof plate is sandwiched between the insulator and the cover body.

7. A method for testing the expansion force of a cylindrical battery electrode, characterized in that: The steps include: Obtain a thin film pressure sensor; Performing a pressure resistance calibration operation on the thin film pressure sensor to obtain a curve showing the change of resistance of the thin film pressure sensor with pressure; Performing a cylindrical battery preparation operation on the thin film pressure sensor to obtain the cylindrical battery pole piece expansion force testing device according to any one of claims 1 to 6; Performing an internal resistance monitoring operation on the cylindrical battery pole piece expansion force testing device to obtain a real-time internal resistance between the positive electrode line and the negative electrode line outside the cylinder; The real-time internal resistance is compared with the curve of the resistance changing with pressure to obtain the expansion force of the cylindrical battery electrode.

8. The method for testing the expansion force of a cylindrical battery electrode according to claim 7, wherein: The cylindrical battery preparation operation for the thin film pressure sensor specifically includes the following steps: Performing a positive and negative lead connection operation on the thin film pressure sensor so that the positive and negative electrodes of the thin film pressure sensor are electrically connected to a positive line and a negative line respectively; Placing the thin film pressure sensor and the battery cell together in a cylinder so that the thin film pressure sensor is in contact with the inner wall of the cylinder and the outer wall of the battery cell respectively; The cylinder is subjected to a liquid injection and sealing operation so that one end of the positive electrode wire and one end of the negative electrode wire are located outside the cylinder.

9. The method for testing the expansion force of a cylindrical battery electrode according to claim 8, characterized in that: Before the step of placing the thin film pressure sensor in a cylinder for placement operation, and after the step of connecting the positive and negative leads of the thin film pressure sensor, the following steps are also included: performing a corrosion-resistant operation on the thin film pressure sensor so that the outer periphery of the thin film pressure sensor is covered with a corrosion-resistant insulating layer, the corrosion-resistant insulating layer includes a first corrosion-resistant insulating layer and a second corrosion-resistant insulating layer, the periphery of the first corrosion-resistant insulating layer and the periphery of the second corrosion-resistant insulating layer are connected to form a built-in cavity, the thin film pressure sensor is arranged in the built-in cavity, and the thin film pressure sensor is respectively abutted against the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer, the positive wire portion is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and is electrically connected to the thin film pressure sensor, and the negative wire portion is sandwiched between the first corrosion-resistant insulating layer and the second corrosion-resistant insulating layer and is electrically connected to the thin film pressure sensor.

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