Central tube and battery

Abstract

The utility model discloses a central tube and a battery, the central tube is used for winding a battery cell, the central tube comprises a hollow tube body, a buffer through groove is limited on the inner circumferential surface of the hollow tube body, and the buffer through groove is communicated with at least one axial end surface of the hollow tube body. In the charging and discharging process of the battery and when the coating of the battery cell pole piece expands, the inner ring of the winding battery cell pole set abuts against the outer circumferential face of the hollow pipe body, the inner ring of the winding battery cell pole set applies stress to the hollow pipe body, the hollow pipe body deforms through the buffering through groove, and the deformation degree adapts to the stress applied by the inner ring of the winding battery cell pole set. The stress of the inner ring of the battery core pole group is relieved, and the safety performance of the battery is improved. The utility model is applied to the field of energy storage elements.

Description

Technical Field

[0001] The utility model relates to the field of energy storage elements, in particular to a central tube and a battery. Background Art

[0002] With the continuous development of battery technology, especially in response to the range anxiety challenges of new energy vehicles, battery capacity is increasing. However, battery height is limited by the vehicle chassis. Therefore, to increase capacity, cylindrical batteries are beginning to develop in the direction of increasing diameter. At the same time, the energy density of graphite is approaching its theoretical limit, and hybrid silicon anodes are becoming the direction of future battery research and development. Currently in mass production, silicon anodes experience significant volume expansion during charge and discharge, with an expansion rate of nearly 300% after full charge. As the diameter of cylindrical batteries increases, the number of electrode layers increases, and the hybrid silicon content increases, the internal stress of the electrode group increases during the cyclic aging process of cylindrical batteries. The inner ring of the electrode has the highest curvature and withstands the greatest pressure, which is the weakest area of ​​the battery.

[0003] In the related art, a hollow metal tube is set at the center position of the wound battery cell. Similar to the limiting effect of the outer shell on the outer ring of the electrode group, the metal tube also plays a supporting and limiting role on the inner ring of the electrode group of the wound battery cell. However, the center tube can only limit the inner ring of the electrode group from continuing to deform toward the center position, but cannot relieve the stress on the inner ring electrode. Utility Model Content

[0004] The present invention aims to solve at least one of the technical problems in the prior art. To this end, the present invention provides a central tube that can improve battery safety performance.

[0005] A battery having the central tube is also provided.

[0006] The central tube according to the embodiment of the first aspect of the present utility model is used for winding a battery core, comprising:

[0007] A hollow tube body, wherein the inner circumferential surface of the hollow tube body defines a buffer groove, and the buffer groove is connected to at least one axial end surface of the hollow tube body;

[0008] A filling portion is provided, wherein the filling portion is filled in the buffer groove.

[0009] The central tube according to the embodiment of the first aspect of the present utility model has at least the following beneficial effects:

[0010] 1. During the battery charging and discharging process and when the coating of the battery cell electrode sheet expands, the inner ring of the wound battery cell electrode group abuts against the outer circumference of the hollow tube body. The inner ring of the battery cell electrode group applies stress to the hollow tube body, and the hollow tube body deforms through the buffer groove and the filling part. The degree of deformation adapts to the stress applied by the inner ring of the battery cell electrode group, thereby alleviating the stress of the inner ring of the battery cell electrode group and improving the safety performance of the battery.

[0011] 2. During the battery charging and discharging process and when the coating on the battery cell electrode shrinks, the stress applied by the electrode is reduced, and the hollow tube can automatically reset and continuously fit with the inner ring of the battery cell electrode group, thereby effectively supporting the inner ring of the battery cell electrode group, improving the fitting effect between the positive and negative electrode sheets in the battery cell, and improving the safety performance of the battery;

[0012] 3. The buffer groove increases the space inside the hollow tube body, and the hollow tube body can accommodate more electrolyte. The exhaust channel when the battery cell uses the exhaust inside the hollow tube body is larger, thereby improving the safety performance of the battery.

[0013] According to some embodiments of the present invention, the hollow tube body includes a plurality of buffer grooves that are sequentially spaced apart along the circumference of the hollow tube body.

[0014] According to some embodiments of the present invention, the plurality of buffer grooves are evenly distributed.

[0015] According to some embodiments of the present invention, the buffer groove includes a first groove side wall and a second groove side wall, and the distance between the first groove side wall and the second groove side wall increases along the direction from the outer circumference to the inner circumference of the hollow tube body.

[0016] According to some embodiments of the present invention, the stiffness of the filling portion is K1, the stiffness of the hollow tube body is K2, and the central tube is configured as follows: K1<K2.

[0017] According to some embodiments of the present invention, the central tube is configured as follows: K1≤0.6*K2.

[0018] According to some embodiments of the present invention, the groove depth of the buffer groove along the radial direction of the hollow tube body is L1, the radial wall thickness of the hollow tube body is L2, and the central tube is configured as follows: 0.2*L2≤L1≤0.8*L2.

[0019] A battery according to an embodiment of the second aspect of the present invention includes:

[0020] The wound battery cell has a central hole along the winding axis;

[0021] The central tube described in the first embodiment is passed through the central hole.

[0022] The battery according to the embodiment of the second aspect of the present utility model has at least the following beneficial effects: using the central tube in the embodiment of the first aspect can effectively reduce the stress of the innermost electrode of the wound battery cell during the battery charging and discharging process, thereby improving the battery safety performance.

[0023] According to some embodiments of the present invention, the length of the central hole along the winding axis is L3, the length of the central tube along the winding axis is L4, and the battery is configured as follows: L3-10mm≤L4≤L3-2mm.

[0024] According to some embodiments of the present invention, the minimum length of the central hole along the winding radial direction is L5, the outer diameter length of the central tube is L6, and the battery is configured as follows: L5-2mm≤L6≤L5-0.5mm.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0027] Figure 1 This is a schematic diagram of the end structure of a central tube according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the three-dimensional structure of the central tube of an embodiment of the present invention when the central tube does not yet have a filling portion;

[0029] Figure 3 This is a structural schematic diagram of a central tube installed in a battery according to an embodiment of the present utility model.

[0030] Figure Number:

[0031] Central tube 1000;

[0032] Hollow tube body 100; buffer groove 110; first groove side wall 111; second groove side wall 112;

[0033] Filling portion 200;

[0034] Winding battery cell 2000; center hole 2100;

[0035] Shell 3000. DETAILED DESCRIPTION

[0036] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0037] In the description of the present invention, it should be understood that descriptions involving orientation, such as the orientation or positional relationship indicated by up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0038] In the description of this utility model, "a number" refers to one or more, and "a plurality" refers to two or more. The use of "first" or "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of the indicated technical features, or implicitly indicating the order of the indicated technical features.

[0039] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0040] The wound battery cell 2000 refers to a spiral formed by rotating a long strip of electrode along its length with the side of one end as the axis of rotation, and a center hole 2100 is formed in the center of the spiral. The closer the electrode is to the center of the spiral, the greater the curvature, that is, the greater the deformation amplitude. The coating on the surface of the electrode has an expansion effect. During the charging and discharging process of the battery, the coating on the surface of the electrode will expand and shrink after expansion. When the electrode expands, the spiral expands as a whole, and the expansion space of the electrode coating closer to the center of the spiral is smaller. At the same time, the curvature of the electrode is also greater, resulting in an increase in the internal stress of the electrode in the center of the spiral. The electrode in the center of the spiral is prone to collapse toward the center hole 2100, which reduces the fitting effect of the electrode and makes lithium deposition easier.

[0041] In the related art, in order to support the electrode at the center of the spiral, a hollow metal tube is inserted into the center hole 2100. Similar to the limiting effect of the outer shell 3000 on the outer ring of the electrode group, the metal tube also plays a supporting and limiting role on the inner ring of the electrode group of the wound battery cell 2000. However, the center tube 1000 can only limit the inner ring of the electrode group from continuing to deform toward the center position, but cannot relieve the stress on the inner ring of the electrode group. Under the action of stress, the electrode coating becomes tighter, and the number of ions that the coating can accommodate is reduced. The ions on the surface of the negative electrode are easily combined with the electrons in the negative electrode to form metal. The metal on the surface of the negative electrode is easy to pierce the diaphragm, causing an internal short circuit, posing a safety hazard.

[0042] Reference Figure 1 、 Figure 2 and Figure 3As shown, the embodiment of the first aspect of the present invention proposes a central tube 1000 for winding the battery core 2000, the central tube 1000 includes a hollow tube body 100 and a filling portion 200, the inner circumference of the hollow tube body 100 is defined with a buffer groove 110, the buffer groove 110 is connected to at least one axial end face of the hollow tube body 100; the filling portion 200, the filling portion 200 is filled in the buffer groove 110.

[0043] The axial direction of the hollow tube body 100 refers to the axial direction of the hollow tube body 100 .

[0044] In this embodiment, the hollow tube body 100 is cylindrical or elliptical or a polygonal column that is approximately cylindrical or elliptical, wherein the edges of the polygonal column can be rounded so that the outer circumference of the hollow tube body 100 fits against the inner circumference of the center hole 2100 of the wound battery cell 2000, thereby avoiding local stress concentration on the inner circumference of the center hole 2100.

[0045] The inner circumference of the hollow tube 100 is provided with a buffer groove 110, which connects the two axial ends of the hollow tube 100. When the hollow tube 100 is subjected to the stress of the pole piece from the outside to the inside, the location of the buffer groove 110 is more likely to deform, and the deformation of the buffer groove 110 causes the entire hollow tube 100 to deform. As another embodiment, the buffer groove 110 connects to one axial end of the hollow tube 100.

[0046] Among them, the buffer groove 110 is arranged axially along the hollow tube body 100, and the buffer groove 110 is a straight groove; or the buffer groove 110 is arranged along the spiral line of the inner circumference of the hollow tube body 100, and the buffer groove 110 is a spiral groove; or the buffer groove 110 is arranged along other line shapes of the inner circumference of the hollow tube body 100, and the buffer groove 110 is scanned and formed along the line direction. For example, if the line shape is a wavy line, the buffer groove 110 is scanned and formed into a wavy groove.

[0047] The filling portion 200 is filled in the buffer groove 110. The filling portion 200 can undergo elastic deformation, so that the hollow tube body 100 can more easily return to its original shape after deformation. The filling portion 200 can also play a certain supporting role, so that the hollow tube body 100 will only deform when it is subjected to a pole piece stress exceeding a preset stress. The hollow tube body 100 has a better support effect on the inner circumference of the center hole 2100.

[0048] It should be noted that during the battery's charge and discharge process, when the coating on the cell electrode expands, the spiral structure of wound cell 2000 influences the inner ring of the electrode assembly, resulting in uneven stress distribution within center hole 2100 and localized stress concentration. The buffer slot 110 and the filling portion 200 can adaptively deform based on the actual stress distribution within center hole 2100 to reduce localized stress concentration. This effectively supports center hole 2100, preventing collapse and improving battery safety. Specifically, the deformation of the buffer groove 110 and the filling portion 200 is outward expansion or inward contraction. Taking the cylindrical hollow tube body 100 as an example, the hollow tube body 100 has four evenly distributed positions along its circumferential direction, and the angle between two adjacent positions is 90°. The buffer groove 110 and the filling portion 200 are located at one of the positions. According to the positional relationship, the remaining three positions are two adjacent positions and one relative position. When the position where the buffer groove 110 and the filling portion 200 are located or the relative position where the buffer groove 110 and the filling portion 200 are located is squeezed by the pole piece stress, the buffer groove 110 and the filling portion 200 expand outward and move toward their relative position; when the position adjacent to the position where the buffer groove 110 and the filling portion 200 are located is squeezed by the pole piece stress, the buffer groove 110 and the filling portion 200 contract inward and move away from their relative position, thereby realizing adaptive adjustment of the buffer groove 110 and the filling portion 200 to the pole piece stress. After deformation, the center tube 1000 is deformed from a cylindrical shape to an approximately elliptical shape. The center tube 1000 can still support the inner circle of the electrode group of the wound battery cell 2000, preventing the center hole 2100 from collapsing, thereby improving the safety performance of the battery.

[0049] It should be noted that the deformation of the hollow tube body 100 under stress is elastic deformation. When the coating of the battery cell electrode shrinks, the stress applied by the electrode is reduced. The hollow tube body 100 can automatically reset by relying on its own elasticity and the elasticity of the filling part 200, and continue to fit with the inner circle of the battery cell electrode group to effectively support the inner circle of the battery cell electrode group, improve the fitting effect between the positive electrode and the negative electrode in the battery cell, and improve the safety performance of the battery; the buffer groove 110 increases the space inside the hollow tube body 100, and the hollow tube body 100 can accommodate more electrolyte. The exhaust channel when the battery cell uses the hollow tube body 100 to vent air is larger, thereby improving the safety performance of the battery.

[0050] Reference Figure 1 As shown, in some specific embodiments of the present invention, the hollow tube body 100 includes a plurality of buffer grooves 110 that are sequentially spaced apart along the circumference of the hollow tube body 100 .

[0051] It is worth understanding that the buffer grooves 110 are distributed in sequence along the axis of the hollow tube body 100, so that the elastic deformation amplitude of the hollow tube body 100 is larger, and each buffer groove 110 can be deformed in two directions, and the hollow tube body 100 can deform in more directions, thereby improving the effect of the hollow tube body 100 in adaptively adjusting the stress of the battery cell pole piece.

[0052] Reference Figure 1 As shown, in some specific embodiments of the present invention, the plurality of buffer grooves 110 are evenly distributed.

[0053] It is worth understanding that when the buffer grooves 110 are evenly distributed, the stress distribution of the hollow tube body 100 itself is more even, which effectively reduces the local stress concentration of the hollow tube body 100 itself and improves the structural strength of the hollow tube body 100.

[0054] Reference Figure 1 and Figure 2 As shown, in some specific embodiments of the present invention, the buffer groove 110 includes a first groove side wall 111 and a second groove side wall 112, and the distance between the first groove side wall 111 and the second groove side wall 112 increases along the direction from the outer circumference to the inner circumference of the hollow tube body 100.

[0055] It is worth understanding that the distance between the first groove sidewall 111 and the second groove sidewall 112 increases gradually, so that the hollow tube body 100 can be deformed to a greater extent, thereby improving the deformation amplitude of the hollow tube body 100 .

[0056] In this embodiment, the manner in which the distance between the first groove side wall 111 and the second groove side wall 112 increases includes but is not limited to the following situations: 1. The distance value continues to increase, and the increase amplitude of the distance value is a fixed value or the increase amplitude is a variable value; 2. The distance value increases intermittently. Specifically, along the direction from the outer circumference to the inner circumference of the hollow tube body 100, the distance value is divided into multiple intervals, and the distance values ​​in some intervals increase, while the distance values ​​in some intervals remain unchanged.

[0057] Specifically, when the initial distance between the first groove sidewall 111 and the second groove sidewall 112 is zero and the distance value continues to increase and the increase amplitude is a fixed value, Figure 1 As shown, the first groove sidewall 111 and the second groove sidewall 112 are angular.

[0058] In some specific embodiments of the present invention, the stiffness of the filling portion 200 is K1, the stiffness of the hollow tube body 100 is K2, and the central tube 1000 is configured as follows: K1 < K2.

[0059] It is worth noting that the stiffness of the filling portion 200 is lower than that of the hollow tube 100, making it more susceptible to elastic deformation and causing deformation of the hollow tube 100. Furthermore, the filling portion 200 supports the hollow tube 100, further increasing the overall stiffness of the central tube 1000 and enhancing its support for the central hole 2100 of the wound battery cell 2000.

[0060] In this embodiment, the central tube 1000 is configured such that: K1≤0.6*K2. The filling portion 200 is made of an organic material or an inorganic material.

[0061] Reference Figure 1 As shown, in some specific embodiments of the present invention, the groove depth of the buffer groove 110 along the radial direction of the hollow tube body 100 is L1, the radial wall thickness of the hollow tube body 100 is L2, and the central tube 1000 is configured as: 0.2*L2≤L1≤0.8*L2.

[0062] It is worth noting that the central tube 1000 needs to both elastically deform and effectively support the central hole 2100 of the wound battery cell 2000. When the central tube 1000 satisfies the following conditions: 0.2*L2≤L1≤0.8*L2, the central tube 1000 exhibits optimal elastic deformation and supports the central hole 2100. The specific dimensions of the central tube 1000 can be selected based on the actual battery requirements.

[0063] Reference Figure 3 As shown, the second embodiment of the present invention proposes a battery, which includes: a wound battery cell 2000 and a central tube 1000 of the first embodiment. The wound battery cell 2000 has a central hole 2100 along the winding axis, and the central tube 1000 is passed through the central hole 2100.

[0064] It is worth understanding that the battery adopts the central tube 1000 in the embodiment of the first aspect, which can effectively reduce the stress of the innermost electrode of the wound battery cell 2000 during the battery charging and discharging process, thereby improving the battery safety performance.

[0065] In this embodiment, the battery further includes a housing 3000, and the wound cell 2000 is sealed and assembled within the housing 3000. The wound cell 2000 includes a positive electrode sheet, a negative electrode sheet, and a separator separating the positive and negative electrode sheets. Both surfaces of the electrode sheets are coated with a coating, the positive electrode is coated with a positive electrode coating, and the negative electrode is coated with a negative electrode coating, such as a graphite-based coating or a silicon-based coating. During the charge and discharge process of the battery, the coating has an expansion effect. Generally speaking, the coating with an expansion effect refers specifically to the negative electrode coating. The expansion effect refers to the volume expansion of the coating during the charge and discharge process, and the expansion is reversible, so during the charge and discharge process, even if the coating has expanded, it can return to its original state. It should be noted that during the battery activation process, a SEI film is formed on the surface of the negative electrode coating, and the negative electrode coating also expands. This volume expansion is irreversible. After the battery is activated, the outer circumference of the central tube 1000 is in contact with the inner circumference of the central hole 2100, and the central tube 1000 is fixed along the axial direction of the central hole 2100; during the battery charging and discharging process, the negative electrode will further expand in volume, and this volume expansion is reversible. The central tube 1000 can also adapt to the stress applied by the electrode group of the wound battery cell 2000 during this process.

[0066] Reference Figure 3 As shown, in some specific embodiments of the present invention, the length of the central hole 2100 along the winding axis is L3, the length of the central tube 1000 along the winding axis is L4, and the battery is configured as: L3-10mm≤L4≤L3-2mm.

[0067] It is worth understanding that the length of the central tube 1000 along the winding axis is shorter than the length of the central hole 2100 along the winding center. The central tube 1000 can be hidden inside the central hole 2100, and the central tube 1000 can coincide with the length of the paint in the wound battery cell 2000 along the winding axis, thereby improving the supporting effect of the central tube 1000 on the corresponding area of ​​the paint in the wound battery cell 2000.

[0068] Reference Figure 3 As shown, in some specific embodiments of the present invention, the minimum length of the central hole 2100 along the winding radial direction is L5, the outer diameter length of the central tube 1000 is L6, and the battery is configured as: L5-2mm≤L6≤L5-0.5mm.

[0069] It is worth understanding that the minimum length of the center hole 2100 is greater than the outer diameter of the center tube 1000 , so the center tube 1000 can be smoothly inserted into the center hole 2100 , making assembly of the center tube 1000 and the wound battery cell 2000 more convenient.

[0070] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A central tube for winding a battery core, characterized in that: include: A hollow tube body, wherein the inner circumferential surface of the hollow tube body defines a buffer groove, and the buffer groove is connected to at least one axial end surface of the hollow tube body; A filling portion is provided, wherein the filling portion is filled in the buffer groove.

2. The central tube according to claim 1, characterized in that: The hollow tube body includes a plurality of buffer grooves that are sequentially spaced apart along the circumference of the hollow tube body.

3. The central tube according to claim 2, characterized in that: The plurality of buffer grooves are evenly distributed.

4. The central tube according to claim 1, characterized in that: The buffer groove includes a first groove side wall and a second groove side wall. Along the direction from the outer circumference to the inner circumference of the hollow tube body, the distance between the first groove side wall and the second groove side wall increases.

5. The central tube according to claim 1, characterized in that: The stiffness of the filling portion is K1, the stiffness of the hollow tube body is K2, and the central tube is configured such that: K1<K2.

6. The central tube according to claim 5, characterized in that: The central tube is configured as follows: K1≤0.6*K2.

7. The central tube according to claim 1, characterized in that: The groove depth of the buffer groove along the radial direction of the hollow tube body is L1, the tube wall thickness of the hollow tube body in the radial direction is L2, and the central tube is configured as follows: 0.2*L2≤L1≤0.8*L2.

8. A battery, characterized in that: include: The wound battery cell has a central hole along the winding axis; The center tube according to any one of claims 1 to 7 is passed through the center hole.

9. The battery according to claim 8, characterized in that: The length of the central hole along the winding axis is L3, the length of the central tube along the winding axis is L4, and the battery is configured as follows: L3-10mm≤L4≤L3-2mm.

10. The battery according to claim 8, characterized in that: The minimum length of the central hole along the winding radial direction is L5, the outer diameter length of the central tube is L6, and the battery is configured as follows: L5-2mm≤L6≤L5-0.5mm.

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