Pre-pressing device

Abstract

The utility model relates to a pre-pressing device which is used for pre-pressing a roll core. The pre-pressing device comprises a base; the first pressing plate and the second pressing plate are arranged in a spaced mode in the first direction; the receding part is arranged on the first pressing plate and located between the first pressing plate and the second pressing plate, and the receding part comprises a reference receding layer and at least one weight reduction receding layer stacked on the side, facing and / or backing on to the second pressing plate, of the reference receding layer; wherein the reference clearance layer is used for avoiding the bending part of the roll core along a second direction perpendicular to the first direction during prepressing, and the edge of at least one side, arranged in the second direction, of the weight reduction clearance layer shrinks inwards relative to the reference clearance layer, so that a stepped structure is formed between the reference clearance layer and the weight reduction clearance layer which are adjacent to each other. The pre-pressing device provided by the utility model can improve the clearance effect and reduce the indentation.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a pre-pressing device. Background Art

[0002] Batteries are widely used in various industries due to their advantages such as high energy density, high operating voltage, no memory and long cycle life.

[0003] In the battery production process, using a pre-pressing device to pre-press the core is an important step. This process can control the thickness of the core, improve the internal gap of the core, and enhance battery performance.

[0004] When the traditional pre-pressing device is pre-pressing, it is easy to cause the pole piece to break due to excessive force at the corner of the winding core bending part, affecting the quality of the battery. In order to solve the above problem, a gap-avoiding component is provided on the pressure plate of the pre-pressing device in the related art to avoid the gap of the bending part of the winding core. However, the gap-avoiding component has a poor gap-avoiding effect, or the indentation at the gap-avoiding part is too deep, resulting in poor battery performance. Utility Model Content

[0005] Based on this, it is necessary to provide a pre-pressing device that can improve the air avoidance effect and reduce indentation to address the above problems.

[0006] A pre-pressing device, used for pre-pressing a winding core, the pre-pressing device comprising:

[0007] The first pressing plate and the second pressing plate are spaced apart along the first direction; and

[0008] A space-avoiding component is disposed on the first pressing plate and located between the first pressing plate and the second pressing plate, wherein the space-avoiding component comprises a reference space-avoiding layer and at least one weight-reducing space-avoiding layer stacked on a side of the reference space-avoiding layer facing toward and / or away from the second pressing plate;

[0009] Among them, the reference air avoidance layer is used to avoid the bending part of the core along a second direction perpendicular to the first direction during pre-compression, and at least one side edge of the weight-reducing air avoidance layer arranged in the second direction is retracted relative to the reference air avoidance layer to form a stepped structure between the adjacent reference air avoidance layer and the weight-reducing air avoidance layer.

[0010] In some embodiments, both side edges of the weight-reducing and air-avoiding layer arranged in the second direction are retracted relative to the reference air-avoiding layer.

[0011] In some embodiments, all of the weight-reducing and air-avoiding layers are stacked on a side of the reference air-avoiding layer facing toward or away from the second pressing plate.

[0012] In some embodiments, all of the weight-reducing and air-avoiding layers are stacked on a side of the reference air-avoiding layer facing the second pressing plate.

[0013] In some embodiments, different weight-saving and air-avoiding layers are retracted at different distances relative to the reference air-avoiding layer in the second direction, so as to form a stepped structure between every two adjacent weight-saving and air-avoiding layers.

[0014] In some embodiments, all of the weight-reducing and air-avoiding layers are stacked on a side of the reference air-avoiding layer facing the second pressure plate; and in the first direction, a distance by which the weight-reducing and air-avoiding layers are retracted relative to the reference air-avoiding layer gradually increases.

[0015] In some embodiments, in the adjacently arranged reference air-avoiding layer and the weight-reducing air-avoiding layer, the weight-reducing air-avoiding layer is retracted by a distance L relative to the reference air-avoiding layer. 1 The difference in the distance between the two adjacent weight-reducing and air-avoiding layers and the reference air-avoiding layer is L. 2 ; 3mm≤L 1 ≤5mm, 3mm≤L 2 ≤5 mm.

[0016] In some embodiments, the total number of layers of the reference air avoidance layer and the weight-reducing air avoidance layer is K, and the single-layer thickness of the reference air avoidance layer and the weight-reducing air avoidance layer is H, 3 layers≤K≤5 layers, 130 microns≤H≤200 microns.

[0017] In some embodiments, in the second direction, the clearance distance between the edge of the reference clearance layer and the corner of the bending portion on the same side is L 3 , 5 mm ≤ L 3 ≤10 mm.

[0018] In some embodiments, the reference air-avoiding layer and the weight-reducing air-avoiding layer are both Teflon layers.

[0019] The above-mentioned pre-stressing device can avoid the first pressure plate and the air avoidance component from directly contacting and squeezing the bent portion during the pre-stressing process by designing the reference air avoidance layer and the weight-reducing air avoidance layer, thereby solving the problem of the pole piece being broken due to excessive force at the corner of the bent portion of the winding core. In addition, by designing the weight-reducing air avoidance layer, the total thickness of all the weight-reducing air avoidance layers superimposed on the reference air avoidance layer is thicker than that of the single-layer reference air avoidance layer, which weakens the problem of poor air avoidance effect due to insufficient thickness of the reference air avoidance layer, and has a better air avoidance effect. Moreover, all the weight-reducing air avoidance layers are also retracted relative to the reference air avoidance layer. In this way, compared with blindly increasing the thickness of the reference air avoidance layer in the related art, the weight can also be reduced, and the risk of excessive indentation due to excessive weight of the reference air avoidance layer is reduced, resulting in better battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a front view of the cooperation between the pre-pressing device and the winding core in one embodiment of the present application.

[0021] Figure 2 This is a schematic diagram of the structure of the pre-pressing device in one embodiment of the present application after the air-avoiding component and the first pressing plate are matched and inverted.

[0022] Figure Number:

[0023] 100, pre-pressing device; 200, winding core;

[0024] 10. first pressing plate; 20. second pressing plate; 30. air-avoiding component; 40. pre-pressing driving member;

[0025] 31. Basic air-avoiding layer; 32. Weight-reducing air-avoiding layer;

[0026] 210, straight portion; 220, bent portion;

[0027] X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0033] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0034] At present, judging from the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as aerospace and other fields. With the continuous expansion of battery application fields, its market demand is also constantly expanding.

[0035] Please also read Figure 1 and Figure 2The battery includes a battery cell, and a winding core 200 is arranged inside the battery cell. The winding core 200 is a component in which an electrochemical reaction occurs in the battery cell, and the quality of the winding core 200 has a great influence on the battery performance.

[0036] Usually, after the core 200 is formed, the pre-pressing device 100 is used to pre-press the core 200 to control the thickness of the core 200, improve the internal gap of the core 200, and improve the battery performance. When the conventional pre-pressing device 100 is pre-pressed, it is easy to cause the corner 230 of the bending portion 220 of the core 200 to be broken due to excessive force, thereby affecting the quality of the core 200.

[0037] In order to solve the above problems, a gas avoidance component 30 is provided on the pressure plate of the pre-pressing device 100 in the related art to avoid the bending portion 220 of the winding core 200. The applicant noted that the gas avoidance component 30 in the related art only includes a reference gas avoidance layer 31. Although the provision of the reference gas avoidance layer 31 for gas avoidance can reduce the risk of electrode fracture, the gas avoidance effect is not good due to the insufficient thickness of the reference gas avoidance layer 31. On the contrary, in order to achieve the gas avoidance effect, blindly increasing the thickness of the reference gas avoidance layer 31 will cause the reference gas avoidance layer 31 to be too heavy, resulting in a deep indentation formed by pre-pressing, which affects the battery performance.

[0038] In order to alleviate the above-mentioned problems, the applicant has designed a pre-pressing device 100 for pre-pressing a winding core 200 after in-depth research. The pre-pressing device 100 includes a pre-pressing drive 40, a first pressing plate 10, a second pressing plate 20 and an air avoidance component 30. The pre-pressing drive 40 is transmission-connected to the first pressing plate 10. The first pressing plate 10 and the second pressing plate 20 are spaced apart along the first direction X. The air avoidance component 30 is disposed on the first pressing plate 10 and is located between the first pressing plate 10 and the second pressing plate 20. The air avoidance component 30 includes a reference air avoidance layer 31 and at least one weight-reducing air avoidance layer 32 stacked on the side of the reference air avoidance layer 31 facing and / or facing away from the second pressing plate 20. Among them, the reference air avoidance layer 31 is used to avoid the bending portion 220 of the air avoidance core 200 along the second direction Y perpendicular to the first direction X during pre-pressing, and at least one side edge of the weight-reducing air avoidance layer 32 arranged in the second direction Y is retracted relative to the reference air avoidance layer 31 to form a stepped structure between the adjacent reference air avoidance layer 31 and the weight-reducing air avoidance layer 32.

[0039] For the convenience of explanation, the following embodiments are all based on Figure 1 When the middle pre-pressing device 100 is in a state, the first direction X is a vertical downward direction, that is, a thickness direction of the winding core 200 , and the second direction Y is a left-right direction, that is, a width direction of the winding core 200 .

[0040] The pre-pressing driving member 40 drives the first pressing plate 10 to drive the air-avoiding member 30 to move downward along the first direction X, so that the air-avoiding member 30 can avoid the bending portion 220 of the winding core 200, and directly press the winding core 200 to complete the pre-pressing of the winding core 200. After a single pre-pressing is completed, the pre-pressing driving member 40 drives the first pressing plate 10 to drive the air-avoiding member 30 to move upward in a direction opposite to the first direction X, and the air-avoiding member 30 is separated from the winding core 200, so as to facilitate the subsequent delivery of the pre-pressed winding core 200 to the next process.

[0041] As an example, the pre-pressing driving component may be a motor, a cylinder or other components, which are not specifically limited here.

[0042] The first pressing plate 10 and the second pressing plate 20 can be made of metal, plastic or other materials with good mechanical strength. The first pressing plate 10 and the second pressing plate 20 can be rectangular, truncated or other shapes, which can be selected according to needs.

[0043] Specifically, at least one weight-reducing air avoidance layer 32 may be stacked on the side of the reference air avoidance layer 31 facing the second pressure plate 20, or at least one weight-reducing air avoidance layer 32 may be stacked on the side of the reference air avoidance layer 31 facing away from the second pressure plate 20, or at least one weight-reducing air avoidance layer 32 may be stacked on both the side of the reference air avoidance layer 31 facing the second pressure plate 20 and the side of the reference air avoidance layer 31 facing away from the second pressure plate 20. The specific arrangement may be as required.

[0044] The reference air avoidance layer 31 and the weight-reducing air avoidance layer 32 can both be Teflon layers (polytetrafluoroethylene, commonly known as "plastic king"), kraft paper layers, steel plate layers, aluminum plate layers, etc., and specific materials can be selected as needed. Taking the reference air avoidance layer 31 and the weight-reducing air avoidance layer 32 as an example, the Teflon layer has the characteristics of acid and alkali resistance and resistance to various organic solvents, which ensures the stability of the Teflon layer. At the same time, the friction coefficient of the Teflon layer is extremely low and has a lubricating function. During the pre-pressing process, it is difficult for it to stick to the winding core 200, which facilitates the separation of the air avoidance component 30 from the winding core 200 after pre-pressing.

[0045] The reference air-avoiding layer 31 and the weight-reducing air-avoiding layer 32 can be formed on the first pressing plate 10 by pasting, evaporation, etc. Taking the evaporation method as an example, the connection between the layers inside the air-avoiding component 30 and between the air-avoiding component 30 and the first pressing plate 10 is more reliable, and the use of external pasting elements is reduced, and the structure is simpler.

[0046] Specifically, the winding core 200 includes a straight portion 210 and a bent portion 220, and there are two straight portions 210 and two bent portions 220, the two straight portions 210 are arranged at intervals along the first direction X, and the two bent portions 220 are arranged at intervals along the second direction Y, and are connected between the two straight portions 210. The reference air avoidance layer 31 and the weight-reducing air avoidance layer 32 are both or substantially rectangular, and the shapes of both are generally adapted to the shape of the winding core 200. The reference air avoidance layer 31 and the weight-reducing air avoidance layer 32 extend along a third direction Z perpendicular to both the first direction X and the second direction Y and completely cover the winding core 200 in this direction.

[0047] For the convenience of explanation, the following embodiments are all based on Figure 1 When the middle pre-pressing device 100 is in a state, the third direction Z is the front-to-back direction, that is, the length direction of the winding core 200 , which is described by way of example.

[0048] Both the reference air avoidance layer 31 and the weight-reducing air avoidance layer 32 completely cover the winding core 200 in the third direction Z, so as to pre-press the winding core 200 along the length direction of the winding core 200 , thereby achieving a better pre-pressing effect.

[0049] Both the reference space-avoiding layer 31 and the weight-reducing space-avoiding layer 32 can avoid the bending portion 220 of the winding core 200 along the second direction Y. When the reference space-avoiding layer 31 and the weight-reducing space-avoiding layer 32 avoid the bending portion 220 of the winding core 200, the projections of the reference space-avoiding layer 31 and the weight-reducing space-avoiding layer 32 in the first direction X both fall into the straight portion 210.

[0050] According to the size of the winding core 200 currently available on the market, the clearance distance between the edge of the reference clearance layer 31 and the corner 230 of the bending portion 220 on the same side in the second direction Y is designed to be L 3 , 5 mm ≤ L 3 ≤10 mm. Under this design, the reference air-avoiding layer 31 can basically avoid the air of most sizes of the winding core 200 on the market, and can cover more of the straight portion 210, so it has strong versatility and excellent pre-compression effect.

[0051] The two positions of the two bending portions 220 that are farthest apart in the second direction Y are the two bending corners 230 (specifically, Figure 1 (as indicated by the middle label A).

[0052] In addition to the function of the air-avoiding bent portion 220, the weight-reducing air-avoiding layer 32 is also inwardly contracted compared to the reference air-avoiding layer 31, so the air-avoiding distance between the edge of the weight-reducing air-avoiding layer 32 on the same side and the corner 230 of the bent portion 220 is greater than L 3 The weight-reducing air avoidance layer 32 is retracted relative to the reference air avoidance layer 31 . Therefore, the weight-reducing air avoidance layer 32 has a smaller weight than the reference air avoidance layer 31 , and the air avoidance component 30 can be reduced in weight.

[0053] The reference air avoidance layer 31 and the weight-reducing air avoidance layer 32 both have two side edges spaced apart along the second direction Y. The two side edges of the reference air avoidance layer 31 are defined as the first base edge and the second base edge, respectively, and the two side edges of the weight-reducing air avoidance layer 32 are defined as the first weight-reducing edge and the second weight-reducing edge, respectively. The first base edge and the first weight-reducing edge are located on the same side, and the second base edge and the second weight-reducing edge are located on the other side. Figure 1 The state of the middle preloading device 100 is described by taking an example in which the first base edge and the first weight-reducing edge are located on the left side, and the second base edge and the second weight-reducing edge are located on the right side.

[0054] At least one side edge of the weight-reducing and air-avoiding layer 32 is retracted relative to the reference air-avoiding layer 31. For example, the first weight-reducing edge of the weight-reducing and air-avoiding layer 32 is retracted relative to the first base edge of the reference air-avoiding layer 31, or the second weight-reducing edge of the weight-reducing and air-avoiding layer 32 is retracted relative to the second base edge of the reference air-avoiding layer 31, or the first weight-reducing edge of the weight-reducing and air-avoiding layer 32 is retracted relative to the first base edge of the reference air-avoiding layer 31, and at the same time, the second weight-reducing edge of the weight-reducing and air-avoiding layer 32 is retracted relative to the second base edge of the reference air-avoiding layer 31.

[0055] All weight-reducing and air-avoiding layers 32 are retracted relative to the reference air-avoiding layer 31 , but different weight-reducing and air-avoiding layers 32 may be retracted relative to the reference air-avoiding layer 31 by the same or different distances, so that a stepped structure can be formed between adjacent reference air-avoiding layers 31 and weight-reducing and air-avoiding layers 32 .

[0056] By designing the reference air avoidance layer 31 and the weight-reducing air avoidance layer 32, the first pressure plate 10 and the air avoidance component 30 can be prevented from directly contacting and squeezing the bent portion 220 during the pre-pressing process, thereby solving the problem of the electrode breaking due to excessive force at the corner 230 of the bent portion 220 of the winding core 200. In addition, by designing the weight-reducing air avoidance layer 32, the total thickness of all the weight-reducing air avoidance layers 32 superimposed on the reference air avoidance layer 31 is thicker than that of the single-layer reference air avoidance layer 31, which weakens the problem of poor air avoidance effect caused by insufficient thickness of the reference air avoidance layer 31, and has a better air avoidance effect. Moreover, all the weight-reducing air avoidance layers 32 are also retracted relative to the reference air avoidance layer 31. In this way, compared with the related art of blindly increasing the thickness of the reference air avoidance layer 31, it can also reduce weight and reduce the risk of excessive indentation due to excessive weight of the reference air avoidance layer 31, so that the battery performance is better.

[0057] As an example, the total number of layers of the reference air avoidance layer 31 and the weight-reducing air avoidance layer 32 is K, and the single-layer thickness of the reference air avoidance layer 31 and the weight-reducing air avoidance layer 32 is H, 3 layers ≤ K ≤ 5 layers, 130 microns ≤ H ≤ 200 microns. Under this design, the total thickness between the reference air avoidance layer 31 and all the weight-reducing air avoidance layers 32 is not too thick, and the total weight of the reference air avoidance layer 31 and all the weight-reducing air avoidance layers 32 is also appropriate, which is conducive to further reducing the risk of excessive indentation and optimizing battery performance.

[0058] In some embodiments, both side edges of the weight-reducing and air-avoiding layer 32 disposed in the second direction Y are indented relative to the reference air-avoiding layer 31. That is, the first weight-reducing edge of the weight-reducing and air-avoiding layer 32 is indented relative to the first base edge of the reference air-avoiding layer 31, and at the same time, the second weight-reducing edge of the weight-reducing and air-avoiding layer 32 is indented relative to the second base edge of the reference air-avoiding layer 31. Such a weight-reducing and air-avoiding layer 32 has a better air-avoiding and weight-reducing effect, and the two indentations formed on both sides of the air-avoiding component 30 on the winding core 200 are both shallow, thereby achieving the purpose of improving battery performance.

[0059] In some embodiments, all the weight-reducing and air-avoiding layers 32 are stacked on a side of the reference air-avoiding layer 31 facing toward or away from the second pressing plate 20 .

[0060] That is to say, all the weight-reducing and air-avoiding layers 32 are located on the same side of the reference air-avoiding layer 31. Taking the example that all the weight-reducing and air-avoiding layers 32 are stacked on the side of the reference air-avoiding layer 31 facing away from the second pressing plate 20, in this embodiment, during pre-pressing, the reference air-avoiding layer 31 is in direct contact with the winding core 200. The reference air-avoiding layer 31 has a larger width in the second direction Y than each weight-reducing and air-avoiding layer 32, so that it can more comprehensively cover the straight portion 210 in the second direction Y and pre-press the straight portion 210, which has a better pre-pressing effect.

[0061] Taking the example that all the weight-reducing and air-avoiding layers 32 are stacked on the side of the reference air-avoiding layer 31 facing the second pressure plate 20, in this embodiment, the process of forming the air-avoiding component 30 is based on the reference air-avoiding layer 31, and the weight-reducing and air-avoiding layers 32 are arranged on the reference air-avoiding layer 31. In the second direction Y, since the width of the reference air-avoiding layer 31 is greater than the width of the weight-reducing and air-avoiding layer 32, the weight-reducing and air-avoiding layers 32 with a smaller width are arranged on the reference air-avoiding layer 31 with a larger width, and the reference air-avoiding layer 31 can stably support the weight-reducing and air-avoiding layers 32, so as to improve the ease and reliability of the installation of the weight-reducing and air-avoiding layers 32.

[0062] In some embodiments, different weight-reducing and air-avoiding layers 32 are retracted at different distances relative to the reference air-avoiding layer 31 in the second direction Y, so as to form a stepped structure between each two adjacent weight-reducing and air-avoiding layers 32. Under this design, the air-avoiding component 30 after weight reduction will not be too heavy or too light, and has a better pre-pressing effect, and the indentation formed after pre-pressing is also shallow.

[0063] Furthermore, in some embodiments, in the first direction X, the distance that the weight-reducing air avoidance layer 32 is retracted relative to the reference air avoidance layer 31 gradually increases, so as to form an air avoidance component 30 that gradually converges from both sides to the middle in the second direction Y.

[0064] The winding core 200 formed by the traditional winding method has the bent portions 220 on both sides of the winding core 200 being tight, and the straight portion 210 being loose relative to the bent portions 220. During the pre-pressing process, the stress of the bent portions 220 on both sides is released, causing the pole pieces of the bent portions 220 to be squeezed toward the middle, thereby generating wrinkles on the straight portion 210.

[0065] In the present application, the weight-reducing and air-avoiding layer 32 is designed to gradually increase the distance of its retraction relative to the reference air-avoiding layer 31, and the weight-reducing and air-avoiding layer 32 with the largest retraction distance is in direct contact with the straight portion 210. The weight-reducing and air-avoiding layer 32 with the largest retraction distance has the smallest width, so the weight-reducing and air-avoiding layer 32 can act on the area in direct contact with it and form a large pressure in this area. It can be understood that this area is located on the straight portion 210. In this case, the force on the pole piece of the bent portion 220 is close to the force on the pole piece in contact with the weight-reducing and air-avoiding layer 32 with the largest retraction distance on the straight portion 210, thereby reducing the risk of the pole piece being squeezed from the bent portion 220 to the straight portion 210 and reducing the generation of pole piece wrinkles.

[0066] In some embodiments, in the adjacently arranged reference air-avoiding layer 31 and the weight-reducing air-avoiding layer 32, the weight-reducing air-avoiding layer 32 is retracted by a distance L relative to the reference air-avoiding layer 31. 1 The difference in the distance between the two adjacent weight-reducing and air-avoiding layers 32 and the reference air-avoiding layer 31 is L. 2 ; 3mm≤L 1 ≤5mm, 3mm≤L 2 ≤5 mm.

[0067] by Figure 1 For example, the weight-reducing air-avoiding layer 32 disposed adjacent to and below the reference air-avoiding layer 31 is retracted by a distance L relative to the reference air-avoiding layer 31. 1 In the two adjacent weight-reducing and air-avoiding layers 32, the weight-reducing and air-avoiding layer 32 located at the bottom is retracted by a distance L compared to the weight-reducing and air-avoiding layer 32 located at the top. 2 , 3 mm ≤ L 1 ≤5mm, 3mm≤L2 ≤5 mm.

[0068] Within the scope of this retraction variation rule, both air avoidance and weight reduction can be achieved, and the air avoidance component 30 and the straight portion 210 still have a large contact length in the second direction Y. Therefore, during pre-compression, the indentation formed by the air avoidance component 30 on the straight portion 210 will not be too deep, which is beneficial to improving battery performance.

[0069] The above-mentioned pre-stressing device 100 can avoid the first pressure plate 10 and the air avoidance component 30 from directly contacting and squeezing the bent portion 220 during the pre-stressing process by designing the reference air avoidance layer 31 and the weight-reducing air avoidance layer 32, thereby solving the problem of the pole piece being broken due to excessive force at the corner 230 of the bent portion 220 of the winding core 200. In addition, by designing the weight-reducing air avoidance layer 32, the total thickness of all the weight-reducing air avoidance layers 32 superimposed on the reference air avoidance layer 31 is thicker than that of the single-layer reference air avoidance layer 31, which weakens the problem of poor air avoidance effect caused by insufficient thickness of the reference air avoidance layer 31, and has a better air avoidance effect. Moreover, all the weight-reducing air avoidance layers 32 are also retracted relative to the reference air avoidance layer 31. In this way, compared with the related art of blindly increasing the thickness of the reference air avoidance layer 31, it can also reduce weight and reduce the risk of excessive indentation caused by excessive weight of the reference air avoidance layer 31, so that the battery performance is better.

[0070] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A preloading device, characterized in that: Used for pre-pressing a winding core (200), the pre-pressing device comprises: The first pressing plate (10) and the second pressing plate (20) are arranged at intervals along a first direction (X); and A void avoidance component (30) is disposed on the first pressing plate (10) and is located between the first pressing plate (10) and the second pressing plate (20), wherein the void avoidance component (30) comprises a reference void avoidance layer (31) and at least one weight-reducing void avoidance layer (32) stacked on a side of the reference void avoidance layer (31) facing toward and / or away from the second pressing plate (20); The reference air avoidance layer (31) is used to avoid the bending portion (220) of the winding core (200) along a second direction (Y) perpendicular to the first direction (X) during pre-pressing, and at least one side edge of the weight-reducing air avoidance layer (32) arranged in the second direction (Y) is retracted relative to the reference air avoidance layer (31) to form a stepped structure between the adjacent reference air avoidance layer (31) and the weight-reducing air avoidance layer (32).

2. The preloading device according to claim 1, characterized in that: Both side edges of the weight-reducing and air-avoiding layer (32) arranged in the second direction (Y) are retracted relative to the reference air-avoiding layer (31).

3. The preloading device according to claim 1, characterized in that: All of the weight-reducing and air-avoiding layers (32) are stacked on a side of the reference air-avoiding layer (31) facing toward or away from the second pressing plate (20).

4. The preloading device according to claim 3, characterized in that: All of the weight-reducing and air-avoiding layers (32) are stacked on a side of the reference air-avoiding layer (31) facing the second pressing plate (20).

5. The preloading device according to any one of claims 1 to 4, characterized in that: Different weight-reducing and air-avoiding layers (32) are retracted at different distances relative to the reference air-avoiding layer (31) in the second direction (Y), so as to form a stepped structure between each two adjacent weight-reducing and air-avoiding layers (32).

6. The preloading device according to claim 5, characterized in that: All of the weight-reducing and air-avoiding layers (32) are stacked on the side of the reference air-avoiding layer (31) facing the second pressure plate (20); and in the first direction (X), the distance that the weight-reducing and air-avoiding layers (32) are retracted relative to the reference air-avoiding layer (31) gradually increases.

7. The preloading device according to claim 6, characterized in that: In the adjacently arranged reference air avoidance layer (31) and the weight-reducing air avoidance layer (32), the distance that the weight-reducing air avoidance layer (32) is retracted relative to the reference air avoidance layer (31) is L1, and the difference in the distance that the two adjacently arranged weight-reducing air avoidance layers (32) are retracted relative to the reference air avoidance layer (31) is L2; ​​3 mm≤L1≤5 mm, 3 mm≤L2≤5 mm.

8. The preloading device according to claim 1, characterized in that: The total number of layers of the reference air avoidance layer (31) and the weight-reducing air avoidance layer (32) is K, and the single-layer thickness of the reference air avoidance layer (31) and the weight-reducing air avoidance layer (32) is H, 3 layers≤K≤5 layers, 130 microns≤H≤200 microns.

9. The preloading device according to claim 1, characterized in that: In the second direction (Y), the clearance distance between the edge of the reference clearance layer (31) on the same side and the corner (230) of the bending portion (220) is L3, 5 mm≤L3≤10 mm.

10. The preloading device according to claim 1, characterized in that: The reference air-avoiding layer (31) and the weight-reducing air-avoiding layer (32) are both Teflon layers.

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