Symmetrical battery bag and symmetrical battery

Abstract

The utility model relates to the technical field of batteries, and discloses a symmetrical battery bag and a symmetrical battery, which comprise two layers of aluminum plastic films which are overlapped; the two current collectors are arranged in an overlapped mode, the two current collectors are attached to the two opposite faces of the two layers of aluminum plastic films respectively, and a to-be-tested pole piece structure is suitable for being stacked between the two current collectors; one end of the tab is connected with the current collector, the other end of the tab extends out of the aluminum-plastic films and is arranged at the joint of the edge of the aluminum-plastic films in a sealing manner, and the two layers of aluminum-plastic films are connected at the first side, provided with the tab, of the aluminum-plastic films. According to the utility model, the current collector and the tab are welded and integrated with the aluminum plastic film to form the symmetrical battery bag, the operation can be completed outside the glove box, and then the assembly of the pole piece structure to be tested and the symmetrical battery bag can be completed inside the glove box, so that the influence of moisture and oxygen on the pole piece is avoided, and the authenticity of a symmetrical battery test result is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a symmetrical battery bag and a symmetrical battery. Background Art

[0002] In recent years, with the rapid development of the energy storage industry, lithium-ion batteries have made great progress in material development, pole piece design and other aspects. Reasonable characterization methods are of great significance for evaluating new electrochemical systems and battery updates. Symmetrical batteries are composed of two identical electrodes and are used for electrochemical impedance spectroscopy (EIS) testing to study the internal resistance of the battery. They have the characteristics of high precision and high sensitivity, and can separate different impedances in the system while avoiding the impact on the electrodes and other circuit components. In the prior art, symmetrical batteries are prepared using single-chip batteries, and the conventional assembly steps are electrode stacking-tab welding-liquid injection and sealing. However, the welding equipment in the tab welding process is large and the operation process is cumbersome, which makes it impossible to complete this process in a glove box. The moisture and oxygen in the environment will affect the pole pieces, thereby affecting the authenticity of the symmetrical battery test results. Utility Model Content

[0003] In view of this, the present invention provides a symmetrical battery bag and a symmetrical battery to solve the problem of low authenticity of symmetrical battery test results in the prior art.

[0004] In a first aspect, the present invention provides a symmetrical battery bag, comprising: an aluminum-plastic film, which is stacked in two layers; a current collector, which is stacked in two sheets, and the two sheets of the current collector are respectively adhered to the two opposite sides of the two layers of the aluminum-plastic film, and the electrode structure to be tested is suitable for stacking between the two sheets of the current collector; a pole tab, one end of the pole tab is connected to the current collector, and the other end of the pole tab extends out of the aluminum-plastic film and is sealed at the intersection with the edge of the aluminum-plastic film, and the two layers of the aluminum-plastic film are connected on the first side where the pole tab is provided.

[0005] Beneficial effect: The current collector and the tab are first welded and integrated with the aluminum-plastic film to form a symmetrical battery bag, which can be completed outside the glove box. After that, the assembly of the electrode structure to be tested and the symmetrical battery bag can be completed inside the glove box to avoid the influence of moisture and oxygen on the electrode, thereby ensuring the authenticity of the symmetrical battery test results.

[0006] In an optional embodiment, the two layers of aluminum-plastic films are openably and closably arranged at the second side opposite to the tab, and at the third and fourth sides connecting the first and second sides and opposite to each other, via self-sealing strips.

[0007] Beneficial effect: During the storage of the symmetrical battery bag, the second, third and fourth sides of the two layers of aluminum-plastic film can be sealed by self-sealing strips to protect the current collector and the electrode structure to be tested from contact with external air and moisture, further ensuring the authenticity of the symmetrical battery test results.

[0008] In an optional embodiment, the current collector is a copper foil or an aluminum foil.

[0009] In an optional embodiment, the side length of the current collector is 20 mm to 120 mm; and / or the side length of the tab is 1 mm to 30 mm.

[0010] In the second aspect, the utility model also provides a symmetrical battery, comprising: the above-mentioned symmetrical battery bag; a pole piece structure to be tested, arranged between two pieces of the current collector, and the two layers of the aluminum-plastic film are connected on the second side opposite to the pole ear, and on the third side and fourth side connecting the first side and the second side and arranged oppositely.

[0011] Beneficial effect: The assembly of the symmetrical battery bag and the electrode structure to be tested can be completed in a glove box where both oxygen and moisture are controlled, thus preventing the electrode structure to be tested from coming into contact with moisture and oxygen, which may lead to water absorption and oxidation, and ensuring the authenticity of the symmetrical battery test results.

[0012] In an optional embodiment, the electrode structure to be tested includes: a electrode body, which is composed of two pieces stacked together, and the two pieces of the electrode body are respectively bonded to the two opposite sides of the two pieces of the current collector; a diaphragm, which is stacked between the two pieces of the electrode body; an insulating layer, which is stacked between the diaphragm and one piece of the electrode body, and the insulating layer is provided with a through hole to connect the electrode body and the diaphragm at the through hole.

[0013] Beneficial effect: The shuttle path of lithium ions is limited by the insulating layer with through holes, which avoids the deviation of the effective area caused by the misalignment of the electrode body and ensures the accuracy and consistency of the test results.

[0014] In an optional embodiment, the insulating layer is a polyester film or a polyesterimide film.

[0015] In an optional embodiment, the thickness of the insulating layer is less than 50 μm.

[0016] In an optional embodiment, the through hole is a circular hole or a square hole.

[0017] In an optional embodiment, the through hole is a circular hole with a diameter of 10 mm to 40 mm; or, the through hole is a square hole with a side length of 10 mm to 40 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a schematic diagram of the perspective structure of a symmetrical battery according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic structural diagram of the aluminum-plastic film and the self-sealing strip according to an embodiment of the present utility model;

[0021] Figure 3 This is a cross-sectional schematic diagram of the current collector and the electrode structure to be tested according to an embodiment of the present utility model.

[0022] Description of reference numerals:

[0023] 1. Aluminum-plastic film; 2. Current collector; 3. Tab; 4. Self-sealing strip; 5. Pole structure to be tested; 51. Pole body; 52. Diaphragm; 53. Insulation layer; 531. Through hole. DETAILED DESCRIPTION

[0024] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0025] Half-cell and full-cell are common methods of electrochemical testing. Among them, the life of half-cell is often not long due to the lithium diffusion effect of lithium sheets; full-cell is composed of positive and negative electrodes, and faces challenges in obtaining electrochemical information of a single electrode. When conducting battery attenuation evaluation and mechanism analysis, it is impossible to further locate the positive and negative electrodes. The industry uses three electrodes to separate the positive and negative electrode characteristics of the full battery, but the three electrodes also have the problem of short life and are prone to failure during the cycle. Symmetrical cells have unique advantages in evaluating the thermodynamic and kinetic properties of electrodes. How to improve the consistency of symmetrical cells and obtain accurate information about electrode characteristics is crucial to accelerating the development of the battery industry.

[0026] In the related art, symmetrical batteries are typically prepared using button cells or monolithic cells. When preparing a symmetrical battery using button cells, the electrode pieces are punched into discs of the required size. Under inert conditions, the button cell housing, electrode pieces, electrolyte, diaphragm 52, springs, and gaskets are assembled into a button cell, after which testing and analysis can be performed. When preparing a symmetrical battery using monolithic cells, the electrode piece to be tested is stacked with the diaphragm 52 to form an electrode group. The electrode group is then welded to the electrode tabs 3 and encapsulated in an aluminum-plastic film 1, after which testing and analysis can be performed.

[0027] Symmetrical batteries prepared from button cells are simple to make, with low material costs. The entire assembly process of the electrode to be tested and other components can be completed in a glove box, preventing the electrode to be tested from coming into contact with moisture and oxygen, and the test results of the symmetrical battery are more authentic. However, the two electrode pieces are prone to misalignment during the assembly process, resulting in poor consistency of the symmetrical battery, affecting the accuracy of the symmetrical battery test results. The consistency of the symmetrical battery prepared from a single-piece battery is better than that of the symmetrical battery prepared from a button cell (the area of ​​the single-piece electrode piece is larger than that of the button electrode piece). However, the three steps of electrode assembly welding and electrode tab welding cannot be completed in a glove box. The moisture and oxygen present in the environment will affect the electrode piece (for example, oxygen will come into contact with the SEI film on the surface of the negative electrode to generate side reaction products), thereby affecting the authenticity of the symmetrical battery test results.

[0028] The embodiment of the present utility model provides a symmetrical battery bag and a symmetrical battery, which takes into account the authenticity and accuracy of the symmetrical battery test results. Figures 1 to 3 , describing the embodiments of the present utility model.

[0029] According to an embodiment of the present invention, in one aspect, a symmetrical battery pouch is provided, comprising: an aluminum-plastic film 1, a current collector 2, and a tab 3. The aluminum-plastic film 1 is laminated in two layers, and the current collector 2 is laminated in two sheets. The two sheets of current collector 2 are respectively attached to opposite sides of the two layers of aluminum-plastic film 1, and a pole piece structure 5 to be tested is stacked between the two sheets of current collector 2. One end of the tab 3 is connected to the current collector 2, and the other end of the tab 3 extends out of the aluminum-plastic film 1 and is sealed at the intersection with the edge of the aluminum-plastic film 1. The two layers of aluminum-plastic film 1 are connected on the first side where the tab 3 is located.

[0030] The symmetrical battery bag of this embodiment is formed by first welding the current collector 2 and the pole ear 3 and integrating them with the aluminum-plastic film 1. The operation can be completed outside the glove box. After that, the assembly of the pole piece structure 5 to be tested and the symmetrical battery bag can be completed inside the glove box to avoid the influence of moisture and oxygen on the pole piece, thereby ensuring the authenticity of the symmetrical battery test results.

[0031] It should be noted that a glove box is a laboratory device that fills a box with high-purity inert gas and circulates and filters out the active substances therein. It is also called a vacuum glove box, an inert gas protection box, etc. The main function of a glove box is to remove O2, H2O, and organic gases. It is widely used in ultra-pure environments that are water-free, oxygen-free, and dust-free. In this embodiment, the conductive foil is first cut to a predetermined size to form a current collector 2. The electrode tabs 3 are welded to the current collector 2 outside the glove box. The welded current collector 2 and the electrode tabs 3 are then fixed to the aluminum-plastic film 1. The two layers of aluminum-plastic film 1 and the two current collectors 2 with the electrode tabs 3 are stacked. The two layers of aluminum-plastic film 1, the electrode tabs 3, and the two layers of aluminum-plastic film 1 themselves are top-sealed to form a semi-encapsulated symmetrical battery bag. In this way, by changing the assembly order of the symmetrical batteries, the welding of the tabs 3 is completed outside the glove box, and the stacking of the electrode structure 5 to be tested can be carried out inside the glove box, avoiding contact between the electrode structure 5 to be tested and moisture and oxygen, thereby more realistically reflecting the actual state of the electrode structure 5 to be tested and ensuring the authenticity of the test results of the mechanism analysis and failure analysis.

[0032] In one embodiment, Figure 2 As shown, the two layers of aluminum-plastic film 1 are openably and closably arranged on the second side opposite the tab 3, as well as the third and fourth sides connecting the first and second sides and opposite each other, via self-sealing strips 4. With this arrangement, during storage of the symmetrical battery pouch, the second, third, and fourth sides of the two layers of aluminum-plastic film 1 can be sealed by the self-sealing strips 4, protecting the current collector 2 and the electrode structure to be tested 5 from contact with external air and moisture, further ensuring the authenticity of the symmetrical battery test results.

[0033] It is worth noting that the current collector 2 and the aluminum-plastic film 1 are both square structures, and the first side of the aluminum-plastic film 1 is the side where the tab 3 is provided, that is, Figure 1 and Figure 2 The upper side of the aluminum-plastic film 1 is shown, and correspondingly, the second side of the aluminum-plastic film 1 is Figure 1 and Figure 2 The lower side of the aluminum-plastic film 1, the third side and the fourth side of the aluminum-plastic film 1 are Figure 1 and Figure 2 The left and right sides of the aluminum-plastic film 1 are shown. Therefore, the symmetrical battery pouch of this embodiment is sealed by heat sealing on the top and by self-sealing strips 4 on the bottom, left, and right sides. This ensures a seal around the symmetrical battery pouch when not stacked with the electrode structure 5 to be tested, preventing the current collector 2 from absorbing water and oxidizing. When the symmetrical battery pouch is stacked with the electrode structure 5 to be tested, the two layers of aluminum-plastic film 1 can be opened at the self-sealing strips 4, and the electrode structure 5 to be tested can be stacked between the two current collectors 2.

[0034] It can be understood that the self-sealing strip 4 is a strip-shaped ridge structure and a strip-shaped groove structure that cooperate with each other. The strip-shaped ridge structure and the strip-shaped groove structure are respectively arranged on the two opposite sides of the two layers of aluminum-plastic film 1 and corresponding to the edges of the aluminum-plastic film 1. When sealing, the strip-shaped ridge structure is inserted into the inner part of the strip-shaped groove structure; when opening, the strip-shaped ridge structure is separated from the strip-shaped groove structure.

[0035] It should be noted that in order to achieve heat sealing at the junction of the tab 3 and the edge of the aluminum-plastic film 1, the tab glue can be coated on the tab 3 near the edge of the aluminum-plastic film 1 to heat seal the tab glue with the aluminum-plastic film 1. Furthermore, the heat sealing condition is 160°C-200°C for 5s-20s.

[0036] In one embodiment, the current collector 2 is a copper foil or an aluminum foil. Specifically, the carbon-coated aluminum foil roll or copper foil roll can be cut into the current collector 2 of a predetermined size by metal die cutting or laser cutting.

[0037] It should be noted that the current collector 2 and the tabs 3 welded to the current collector 2 may be made of the same material. For example, the tabs 3 welded to the copper foil current collector 2 are made of copper, while the tabs 3 welded to the aluminum foil current collector 2 are made of aluminum. Furthermore, the two current collectors 2 may both be made of copper foil, both of aluminum foil, or one copper foil and one aluminum foil.

[0038] In one embodiment, the side length of the current collector 2 is 20 mm to 120 mm, and can be formed by cutting a conductive coil with a width of 100 mm to 130 mm.

[0039] In one embodiment, the side length of the tab 3 is 1 mm to 30 mm.

[0040] In one embodiment, the side length of the aluminum-plastic film 1 is 50 mm to 150 mm.

[0041] The method for manufacturing a symmetrical battery bag in this embodiment includes the following steps:

[0042] Step (1): Die-cutting of current collector 2. Take a carbon-coated aluminum foil roll with a width of 116 mm and use a hardware die cutter to cut out current collector 2 with a size of 55 mm*100 mm on a die-cutting machine.

[0043] Step (2): Welding the current collector 2 to the tab 3. Weld the tab 3 with a size of 16mm*20mm to the current collector 2, and use aluminum foil as the welding protection sheet.

[0044] Step (3): Fix the current collector 2. Fix the current collector 2 with the electrode tab 3 welded to the aluminum-plastic film 1. The size of the aluminum-plastic film 1 is 80mm*120mm. Use high-temperature tape to stick the two current collectors 2 to the same layer of aluminum-plastic film 1 at the welding point of the electrode tab 3. Make sure the edges of the two current collectors 2 are aligned as much as possible and the two electrode tabs 3 are symmetrically arranged (such as Figure 1 The left and right arrangement shown in the figure) makes the tab 3 glue flush with the edge of the aluminum-plastic film 1.

[0045] Step 4: Top-seal the aluminum-plastic film 1. Place another layer of aluminum-plastic film 1 of equal size on the current collector 2, aligning the edges of the two layers. Use a heat sealer to heat seal the first side of the two layers of aluminum-plastic film 1 at 195°C for 9 seconds.

[0046] Step (5): The remaining three sides of the aluminum-plastic film 1 are sealed using the self-sealing strips 4 on the second, third and fourth sides of the two layers of aluminum-plastic film 1.

[0047] According to another embodiment of the present invention, a symmetrical battery is provided, comprising: the aforementioned symmetrical battery pouch and a to-be-tested electrode structure 5. The to-be-tested electrode structure 5 is disposed between two current collectors 2, with two layers of aluminum-plastic film 1 connected on a second side opposite the electrode tab 3, as well as on a third side and a fourth side oppositely disposed and connecting the first and second sides. This arrangement enables assembly of the symmetrical battery pouch and to-be-tested electrode structure 5 within a glove box where oxygen and moisture are controlled, preventing the to-be-tested electrode structure 5 from contacting moisture and oxygen, which could lead to water absorption and oxidation, thereby ensuring the authenticity of the symmetrical battery test results.

[0048] It should be noted that in this embodiment, the production of symmetrical battery bags and the assembly of symmetrical battery bags and electrode structures are separated independently. Symmetrical battery bags can be mass-produced and effectively preserved in the early stage. The electrode structure can be assembled into symmetrical batteries without electrode sheets, with electrode sheets, and diaphragms 52 according to actual conditions, thereby improving the flexibility of test items and battery assembly.

[0049] It is worth noting that the two layers of aluminum-plastic film 1 are heat-sealed on the second side, the third side and the fourth side, and the heat-sealing conditions are 160° C.-200° C. for 5s-20s.

[0050] It should be noted that, during heat sealing, the self-sealing strip 4 can play a positioning role, and packaging is achieved on the inner side of the self-sealing strip 4. Optionally, the self-sealing strip 4 can be cut off after heat sealing is completed.

[0051] In one embodiment, Figure 3As shown, the electrode structure 5 to be tested includes a electrode body 51, a diaphragm 52, and an insulating layer 53. The electrode body 51 is stacked in two pieces, and the two electrode bodies 51 are respectively attached to the two opposing surfaces of the two current collectors 2. The diaphragm 52 is stacked between the two electrode bodies 51. The insulating layer 53 is stacked between the diaphragm 52 and one electrode body 51. The insulating layer 53 is provided with a through hole 531, which connects the electrode body 51 and the diaphragm 52 at the through hole 531. In this arrangement, the insulating layer 53 with the through hole 531 is used to limit the shuttle path of lithium ions, avoiding deviations in the effective area caused by misalignment of the electrode body 51, thereby ensuring the accuracy and consistency of the test results.

[0052] It is worth noting that, except for the position of the through hole 531, the insulating layer 53 completely covers the rest of the pole piece body 51. The area of ​​the through hole 531 is smaller than the area of ​​the pole piece body 51. Therefore, lithium ions can only shuttle through the through hole 531. Even if there is a misalignment in the pole piece body 51, it will not affect the effective area of ​​the symmetrical battery, which improves the consistency of the symmetrical battery and thus improves the accuracy of the symmetrical battery test results.

[0053] It should be noted that the two electrode bodies 51 are electrodes of the same polarity, that is, the polarities of the two electrode bodies 51 are both positive or negative.

[0054] In one embodiment, the insulating layer 53 is a polyester film or a polyesterimide film.

[0055] In one embodiment, the thickness of the insulating layer 53 is less than 50 μm.

[0056] In one embodiment, the through hole 531 is a circular hole or a square hole.

[0057] In one embodiment, the through hole 531 is a circular hole with a diameter of 10 mm to 40 mm. In other alternative embodiments, the through hole 531 is a square hole with a side length of 10 mm to 40 mm.

[0058] The symmetrical battery manufacturing method of this embodiment includes the following steps:

[0059] Step (1): Perform pre-processing work for symmetrical battery production, and transfer the prepared symmetrical battery bag, electrode body 51, diaphragm 52, insulating layer 53, small heat sealer, electrolyte, etc. into the glove box, wherein the electrode body 51 has a size of 50mm*96mm, the diaphragm 52 has a size of 59mm*106mm, the insulating layer 53 has a size of 70mm*110mm, and the through hole 531 of the insulating layer 53 is a circular hole with a diameter of 25mm.

[0060] Step (2): Open the self-sealing strip 4 of the symmetrical battery bag, and place the electrode body 51, diaphragm 52, insulating layer 53, and electrode body 51 into the symmetrical battery bag in order to complete the assembly of the electrode structure. Use high-temperature tape to stick the electrode body 51 and the current collector 2 together.

[0061] Step 3: Use a small heat sealer to heat seal the second and third sides of the symmetrical battery pouch at 195°C for 10 seconds. Inject 2g of electrolyte into the unsealed fourth side and heat seal the pouch at 195°C for 10 seconds.

[0062] Step 4: After the symmetrical battery is assembled, it is transferred out of the glove box and tested after the electrolyte is fully soaked for 24 hours. Before testing, the symmetrical battery needs to be clamped with a steel clamp with a clamping pressure of 500N to ensure the fit between the layers and the consistency of the battery test.

[0063] It is worth noting that the electrolyte immersion time can be from 8 to 30 hours, and the clamping pressure can be from 10 N to 1000 N. A rigid steel clamp is used to clamp the symmetrical battery to avoid deformation of the clamp during clamping, which may affect the battery test results.

[0064] It should be further explained that the clamp includes an upper steel plate, a lower steel plate and bolts. The symmetrical battery is located between the upper steel plate and the lower steel plate. The upper steel plate and the lower steel plate are connected and fixed by bolts to provide clamping force to the symmetrical battery.

[0065] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations shall fall within the scope defined by the appended claims.

Claims

1. A symmetrical battery bag, characterized in that: include: Aluminum-plastic film (1), with two layers stacked; The current collector (2) is stacked in two sheets, and the two sheets of the current collector (2) are respectively attached to two oppositely disposed surfaces of the two layers of the aluminum-plastic film (1), and the electrode structure (5) to be tested is stacked between the two sheets of the current collector (2); A pole tab (3), one end of the pole tab (3) is connected to the current collector (2), the other end of the pole tab (3) extends out of the aluminum-plastic film (1) and is sealed at the intersection with the edge of the aluminum-plastic film (1), and the two layers of the aluminum-plastic film (1) are connected and arranged on the first side where the pole tab (3) is provided.

2. The symmetrical battery bag according to claim 1, characterized in that: The two layers of aluminum-plastic films (1) are both openable and closable on the second side opposite to the tab (3), and on the third and fourth sides connecting the first and second sides and opposite to each other, via self-sealing strips (4).

3. The symmetrical battery bag according to claim 1 or 2, characterized in that: The current collector (2) is a copper foil or an aluminum foil.

4. The symmetrical battery bag according to claim 1 or 2, characterized in that: The side length of the current collector (2) is 20 mm to 120 mm; and / or, The side length of the tab (3) is 1 mm to 30 mm.

5. A symmetrical battery, characterized in that: include: The symmetrical battery bag according to any one of claims 1 to 4; The electrode structure (5) to be tested is arranged between the two current collectors (2), and the two layers of the aluminum-plastic film (1) are connected on the second side opposite to the electrode tab (3), and on the third side and the fourth side connecting the first side and the second side and arranged opposite to each other.

6. The symmetrical battery according to claim 5, characterized in that: The electrode structure to be tested (5) comprises: The pole piece body (51) is composed of two pieces stacked together, and the two pieces of the pole piece body (51) are respectively attached to two oppositely disposed surfaces of the two pieces of the current collector (2); A diaphragm (52) is stacked between the two pole pieces (51); An insulating layer (53) is stacked between the diaphragm (52) and a piece of the pole piece body (51), and the insulating layer (53) is provided with a through hole (531) so that the pole piece body (51) and the diaphragm (52) are connected at the through hole (531).

7. The symmetrical battery according to claim 6, characterized in that: The insulating layer (53) is a polyester film or a polyesterimide film.

8. The symmetrical battery according to claim 6, characterized in that: The thickness of the insulating layer (53) is less than 50 μm.

9. The symmetrical battery according to claim 6, characterized in that: The through hole (531) is a circular hole or a square hole.

10. The symmetrical battery according to claim 9, characterized in that: The through hole (531) is a circular hole, and the diameter of the circular hole is 10 mm to 40 mm; or, The through hole (531) is a square hole, and the side length of the square hole is 10 mm to 40 mm.

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