Central tube and battery

Abstract

The utility model relates to the technical field of batteries, particularly provides a central tube and a battery, and aims to solve the problem that the diving phenomenon in the later period of battery circulation cannot be solved by arranging a central circular tube in the prior art. In order to achieve the purpose, a central tube is inserted into a central hole of a battery cell, the central tube extends in the axial direction of the central hole, the central tube comprises an outer tube and a supporting structure arranged in the outer tube, and at least one of the outer tube and the supporting structure can adjust the diameter of the central tube. According to the utility model, the diameter of the central tube is automatically adjusted, so that no matter how many times the battery is charged or discharged for cycle use, effective support can be provided through the central tube, and the overall binding force to the battery core can be controlled within a relatively proper range, thereby avoiding the diving phenomenon in the later cycle period of the battery, and improving the service life of the battery. The cycle performance of the battery is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and specifically provides a central tube and a battery. Background Art

[0002] Lithium-ion batteries are increasingly used in the field of new energy vehicles due to their high energy density, good power performance, and long cycle life. Among the many types of lithium-ion batteries, cylindrical lithium-ion batteries (hereinafter referred to as cylindrical batteries) occupy an important position in the new energy market due to their advantages such as good safety performance, high production efficiency, and low cost.

[0003] Cylindrical batteries usually consist of an outer shell and a battery cell arranged in the outer shell, wherein the outer shell is usually a metal shell, and the battery cell is usually formed by winding a positive electrode sheet and a negative electrode sheet. During the charging and discharging process, the positive and negative electrode sheets will expand. Due to the rigid constraints of the metal shell, the positive and negative electrode sheets can only be squeezed toward the center. In order to cope with the expansion of the positive and negative electrode sheets, there is usually a center hole in the center of the wound battery cell, and the center hole extends along the height direction of the battery cell. As the cylindrical battery is charged and discharged for multiple cycles, multiple extrusions may cause the center hole to deform, resulting in problems such as poor fitting of the positive and negative electrode sheets leading to lithium precipitation, electrode sheet powder loss, or structural collapse leading to short circuits, causing the cylindrical battery to dive in the later stages of the cycle and even safety accidents.

[0004] In order to solve the problem of the center hole being deformed due to extrusion, a center tube is usually inserted into the center hole to provide structural support. However, since the center tube is generally made of metal aluminum, steel and other materials, it has high strength. In the later stages of the cycle of cylindrical batteries, the center tube and the metal shell have a large binding force on the battery cell, and excessive binding force can cause diving in the later stages of the cycle, and even safety accidents.

[0005] Accordingly, the art needs a new technical solution to solve the above problems. Utility Model Content

[0006] The utility model aims to solve the above technical problem, that is, to solve the problem that the prior art cannot solve the diving phenomenon in the late stage of battery cycle by setting a central circular tube.

[0007] In a first aspect, the utility model provides a center tube, which is inserted into the center hole of the battery cell and extends axially along the center hole. The center tube includes an outer tube and a support structure arranged in the outer tube, and at least one of the outer tube and the support structure can adjust the diameter of the center tube.

[0008] In the case of adopting the above technical solution, by setting the central tube to a structure with adjustable diameter, during the battery charging process, the pole pieces of the battery cell expand and generate extrusion force inward, and the diameter of the central tube can be reduced after being squeezed. During the battery discharging process, the pole pieces shrink, the extrusion force gradually decreases, and the diameter of the central tube increases until it returns to its original state. In this way, by adjusting the diameter of the central tube under the action of external force, no matter how many times the battery is cycled for charging and discharging, the central tube can provide effective support to avoid deformation of the central hole due to the extrusion of the battery cell, and the diameter of the central tube can be adjusted to change dynamically with the expansion and contraction of the battery cell, so that the overall binding force of the metal shell and the central tube on the battery cell can be controlled within a more appropriate range, thereby avoiding the phenomenon of diving in the late stage of the battery cycle and effectively improving the cycle performance of the battery.

[0009] In an optional technical solution of the above central tube, the outer tube extends axially along the central hole, and the support structure is configured to adjust the diameter of the outer tube under the action of an external force.

[0010] By making the central tube include two parts, the outer tube and the support structure, and adjusting the diameter of the outer tube through the support structure, the purpose of adjusting the diameter of the central tube can be achieved. During the battery charging and discharging cycle, the outer tube can always provide effective support to the battery cell to avoid deformation of the central hole of the battery cell, and the binding force on the battery cell can be controlled within a more appropriate range through the adjustment of the support structure, effectively improving the cycle performance of the battery.

[0011] In an optional technical solution of the above-mentioned central tube, the support structure includes a support shaft and at least one support spring plate arranged on the support shaft, the support shaft extends axially along the outer tube, and the support spring plate is arranged to adjust the distance between the support shaft and the inner wall of the outer tube under the action of external force.

[0012] In an optional technical solution of the above-mentioned central tube, there are multiple supporting springs, and there is a gap between two adjacent supporting springs. The supporting springs are extended and retracted along the radial direction of the central hole.

[0013] The support structure composed of a support shaft and a plurality of support springs will shrink and deform radially inward when subjected to external pressure, and the outer tube will shrink synchronously, that is, the diameter of the center tube will decrease. When the external pressure decreases, the external pressure on the support structure decreases, and the support springs gradually return to their original state under their own resilience, and the outer tube will become larger, that is, the diameter of the center tube will become larger. With such a setting, when the pole pieces of the battery cell expand or contract during the battery charge and discharge cycle, the diameter of the center tube can also be reduced or increased accordingly, thereby ensuring that effective support is always provided for the battery cell, avoiding deformation of the center hole due to the extrusion of the battery cell, which in turn causes diving in the late cycle.

[0014] In an optional technical solution of the above-mentioned central tube, along the axial projection of the central tube, the supporting spring sheet is extended along the axial direction of the supporting shaft.

[0015] In an optional technical solution of the above central tube, along the radial projection of the central tube, the supporting spring piece is arranged to be an arc-shaped structure or a spiral structure extending along the supporting axis toward the outer tube.

[0016] In the optional technical solution of the above-mentioned central tube, the wall thickness of the outer tube ranges from 0.2 mm to 1 mm.

[0017] In the optional technical solution of the above-mentioned central tube, the number of the supporting spring pieces is 4 to 12.

[0018] In an optional technical solution of the above-mentioned central tube, the support shaft is a solid structure.

[0019] In a second aspect, the utility model further provides a battery, comprising a battery cell and a central tube as described in any of the above schemes.

[0020] It should be noted that the battery has all the technical effects of the central tube described in any of the aforementioned solutions, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0022] Figure 1 This is a structural diagram of a central tube of an embodiment of the utility model;

[0023] Figure 2 It is a top view of a central tube of an embodiment of the utility model;

[0024] Figure 3 It is a schematic diagram of the diameter change of the central tube of an embodiment of the utility model;

[0025] Figure 4 It is a cross-sectional view of a cylindrical battery according to an embodiment of the utility model.

[0026] List of reference numerals:

[0027] 1. Shell; 2. Battery cell; 3. Center tube; 31. Outer tube; 32. Support structure; 321. Support shaft; 322. Support spring. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0029] It should be noted that, in the description of the present invention, the terms "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0030] In addition, it should be noted that in the description of this application, unless otherwise clearly specified and limited, the terms "connected" and "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0031] At present, a central circular tube made of metal aluminum, steel or other materials is usually inserted into the central hole of the battery cell, and the central circular tube is used to support the central hole to prevent the central hole from being deformed due to extrusion. However, since the binding force exerted by the central circular tube and the metal shell on the battery cell is relatively large, it is easy to cause diving in the late stage of the cycle. To this end, the utility model sets the central tube into a structure with adjustable diameter. During the battery charging and discharging process, the diameter of the central tube can dynamically change with the expansion and contraction of the battery cell. In this way, the central tube can provide effective support and control the binding force within a more appropriate range, thereby avoiding diving in the late stage of the battery cycle.

[0032] Refer to the following Figures 1 to 4 To illustrate possible implementations of the central tube of the utility model.

[0033] like Figures 1 to 4As shown, the cylindrical battery includes a shell 1, a battery cell 2 and a central tube 3 arranged in the shell 1. The shell 1 is usually made of metal aluminum, copper and other materials. The battery cell 2 is usually wound by a positive electrode sheet, a negative electrode sheet and a diaphragm, and a central hole is arranged in the center. The central hole is roughly cylindrical. The central tube 3 is inserted in the central hole and extends along the axial direction of the central hole. The central tube 3 is set as an elastic structure with adjustable diameter, which means that the diameter of the central tube 3 can be increased or decreased.

[0034] During the charging process of the cylindrical battery, the positive and negative plates expand, generating an inward squeezing force, reducing the diameter of the central hole and forming a radial squeezing force on the central tube 3. After being squeezed, the diameter of the central tube 3 can be reduced accordingly. Figure 3 As shown in , the center tube 3 changes from a to b. During the discharge process of the cylindrical battery, the positive and negative electrode sheets shrink, the squeezing force on the center tube 3 gradually decreases, and the diameter of the center tube 3 increases until it returns to its original state, as shown in Figure 3 As shown in , the center tube 3 changes from b to a. That is to say, through the spontaneous adjustment of the diameter of the center tube 3, the center tube 3 is in contact with the inner wall of the center hole to provide effective support for the battery cell 2, thereby avoiding the occurrence of lithium precipitation, powder loss, structural collapse and other problems. Since the diameter of the center tube 3 will shrink to a certain extent when the positive and negative plates expand, a certain space will be released for the battery cell 2, which can reduce the binding force of the center tube 3 and the shell 1 on the battery cell 2, thereby avoiding the occurrence of diving. And since the diameter of the center tube 3 can be adjusted spontaneously with the size of the pressure it bears, even if the expansion degree of the positive and negative plates changes with the increase in the number of battery cycles, the diameter of the center tube 3 can also provide effective support for the center hole while releasing appropriate space for the battery cell 2, thereby minimizing the overall binding force of the shell 1 and the center tube 3 on the battery cell 2, and controlling it within a more suitable range, thereby avoiding the diving phenomenon in the later stage of the battery cycle, and effectively improving the battery cycle performance.

[0035] like Figures 1 to 4 As shown, the center tube 3 includes an outer tube 31 and a support structure 32. The outer tube 31 is roughly a hollow cylindrical structure, which is extended along the axial direction of the center hole, and the length is roughly the same as the length of the center hole. The outer tube 31 is made of elastic material, and its inner and outer walls are smooth and flat, and have a certain elastic function. When subjected to external pressure, the outer tube 31 shrinks inward, and when the external pressure decreases or disappears, the outer tube 31 returns to its original state. During the shrinkage or rebound process of the outer tube 31, the outer surface of the outer tube 31 fits with the inner wall of the center hole, so that it can ensure that the pressure on all parts of the center hole is relatively uniform, so that it can provide comprehensive support for the battery cell 2 along the axial direction of the center hole, and avoid lithium deposition or breakage of the positive / negative electrode sheets due to uneven local force.

[0036] The support structure 32 is arranged in the outer tube 31, and includes a support shaft 321 made of metal such as aluminum and copper and 8 support springs 322, wherein the support shaft 321 is a substantially cylindrical solid structure, and its diameter is much smaller than the diameter of the outer tube 31. The 8 support springs 322 are evenly distributed along the circumference of the support shaft 321, and there is a gap between two adjacent support springs 322. One end of each support spring 322 is connected to the support shaft 321, and the other end is connected to the inner wall of the outer tube 31, and can be extended and retracted along the radial direction of the center hole. Along the radial projection of the center tube 3, the support spring 322 is arranged as an arc structure. Along the axial projection of the center tube 3, the support spring 322 is arranged to extend along the axial direction of the support shaft 321, that is, the length of the 8 support springs 322 is substantially the same as the length of the support shaft 321. In other embodiments of the present invention, the number of the supporting spring piece 322 may be one, and along the radial projection of the central tube 3 , the supporting spring piece 322 is a spiral structure extending along the supporting shaft 321 toward the outer tube 31 .

[0037] Based on the above arrangement, during the charging process of the cylindrical battery, the positive and negative plates expand, and a pressure perpendicular to the surface of the outer tube 31 is applied to the outer tube 31, and the outer tube 31 is squeezed inwardly along its radial direction. After being squeezed, the outer tube 31 shrinks inwardly, and the supporting spring sheet 322 shrinks accordingly, and the diameter of the central tube 3 decreases. Figure 3 During the discharge process of the cylindrical battery, the positive and negative electrodes shrink to their original state, the pressure on the central tube 3 gradually decreases, the outer tube 31 and the supporting spring 322 gradually return to their original state under their own elastic force, and the diameter of the central tube 3 returns to its original state, as shown in FIG. Figure 3 The change from b to a in the figure. With such a setting, the purpose of adjusting the diameter of the center tube 3 according to the magnitude of the pressure it is subjected to is achieved. In addition, since the pressure is applied uniformly along the radial direction of the outer tube 31 and to all parts of the axial direction of the outer tube 31, the center tube 3 also contracts uniformly inward along the radial direction after being subjected to external pressure. Similarly, the center tube 3 also rebounds uniformly outward when it rebounds. In this way, the center tube 3 can provide support for the battery cell 2 more uniformly, and can also uniformly adjust the circumferential and axial restraints of the shell 1 and the center tube 3 on the battery cell 2, thereby better avoiding the occurrence of structural collapse or even diving, better improving the cycle performance of the battery, and enhancing the overall performance of the battery.

[0038] In this embodiment, the length of the supporting spring piece 322 and the supporting shaft 321 is approximately Figure 4 The vertical dimensions of the middle support spring 322 and the support shaft 321 are as follows. Figure 4 The vertical direction of the center hole is approximately Figure 4 Horizontal direction in .

[0039] It should be noted that the outer tube 31 can be made of elastic materials such as rubber, polyurethane thermoplastic elastomer, styrene thermoplastic elastomer, olefin thermoplastic elastomer, dynamically vulcanized thermoplastic elastomer, polyester thermoplastic elastomer, polyamide thermoplastic elastomer, etc. Obviously, the outer tube 31 can also be made of a softer metal such as copper, tin, or a memory alloy instead of the aforementioned elastic materials. In this case, the outer tube 31 can be set to a cylindrical structure with small corrugations. When subjected to external pressure, the outer tube 31 is compressed, the distance between the peaks of two adjacent corrugations on the outer tube 31 is reduced, and the diameter of the outer tube 31 is reduced. When the external pressure is reduced or disappears, the distance between the peaks of two adjacent corrugations on the outer tube 31 increases, and the diameter of the outer tube 31 becomes larger and returns to its original state. Without departing from the basic principles of the present application, those skilled in the art can flexibly select the specific setting method of the outer tube 31 according to the specific application scenario, as long as the outer tube 31 has a certain elastic function and its diameter can change with the size of the extrusion force it is subjected to.

[0040] It should be noted that, along the radial projection of the central tube 3, the support spring piece 322 may not be set to an arc structure, but may be set to other possible shapes such as a corrugated structure, a curved surface structure, etc. Observed along the axial direction of the central tube 3, the support spring piece 322 may not be set along the axial direction of the support shaft 321. For example, the length of the support spring piece 322 is much smaller than the length of the support shaft 321. That is to say, the central tube 3 includes a plurality of shorter support spring pieces 322, which are arranged in an array on the outer surface of the support shaft 321 to provide a relatively uniform radial support force and axial support force for the battery cell 2. Without departing from the basic principles of the present application, those skilled in the art can flexibly select the specific setting method of the support spring piece 322 according to the specific application scenario, as long as it can provide elastic force, shrink inward when subjected to external pressure, and rebound to its original state when the external pressure decreases or disappears.

[0041] It should be noted that the support shaft 321 can also be set as a cylindrical hollow structure. Obviously, the support shaft 321 can also be set as a hollow or solid columnar structure with a cross section of a square, hexagonal or other possible shapes. Without departing from the basic principles of the present application, those skilled in the art can flexibly select the specific setting form of the support shaft 321 according to the specific application scenario, as long as it can provide uniform and sufficient support force in the radial direction when the central tube 3 is compressed, and avoid the collapse of the support structure 32 or even the central tube 3.

[0042] Preferably, the number of supporting spring clips 322 ranges from 4 to 12, and the supporting spring clips 322 within this number range can provide sufficient supporting force. It should be noted that the circumference of the supporting shaft 321 can also be provided with 1, 2, 4, 6, 8, 10, 12 or other numbers of supporting spring clips 322. Without departing from the basic principles of the present application, technical personnel in this field can flexibly select the specific number of supporting spring clips 322 according to specific application scenarios, as long as these supporting spring clips 322 can provide sufficient supporting force, can shrink accordingly when under pressure so as to reduce the binding force of the central tube 3 on the battery core 2, and can gradually return to their original state under the action of their own elastic force when the external pressure is reduced or disappears.

[0043] It should be noted that the axial direction of the central tube 3 is approximately Figure 3 In the vertical direction, the radial direction of the central tube 3 is approximately Figure 3 Horizontal direction in .

[0044] In a possible implementation, the wall thickness of the outer tube 31 is in the range of 0.2 mm to 1 mm. The outer tube 31 of this thickness has sufficient strength and will not be damaged due to the pressure exerted by the expansion of the pole piece, thereby causing lithium deposition or fracture of the positive / negative pole piece. At the same time, the outer tube 31 within this wall thickness range can also deform in time when subjected to external pressure, shrinking inward to leave space for the expansion of the positive and negative pole pieces, reducing the binding force of the central tube 3 on the battery cell 2, and controlling the binding force on the battery cell 2 within a more appropriate range. Through such a setting, the cycle performance of the battery can be better improved, and the diving phenomenon in the later stage of the battery cycle can be avoided.

[0045] It should be noted that the central tube 3 may not be composed of the outer tube 31 and the support structure 32, but only includes the outer tube 31. The outer tube 31 is made of elastic material and can shrink when under pressure and rebound to its original state when the pressure is reduced or disappears. Of course, the outer tube 31 can also be configured as a structure similar to a shutter formed by overlapping and connecting multiple sheet structures in sequence. When subjected to external pressure, the overlapping parts of each sheet structure increase, and the diameter of the outer tube 31 decreases. When the external pressure decreases or disappears, the overlapping parts of each sheet structure decrease, and the diameter of the outer tube 31 becomes larger and returns to its original state. Without departing from the basic principles of the present application, those skilled in the art can flexibly select the specific setting method of the central tube 3 according to the specific application scenario, as long as the diameter of the central tube 3 can change with the expansion and contraction of the positive and negative electrodes, provide effective support for the battery cell 2, and reduce the binding force of the central tube 3 and the shell 1 on the battery cell 2.

[0046] In summary, in the preferred technical solution of the utility model, by setting the central tube 3 to a structure with adjustable diameter, no matter how many times the battery is used for charge and discharge cycles, the central tube 3 can provide effective support, and the overall binding force of the metal shell and the central tube 3 on the battery core can be controlled within a more appropriate range, so that the central hole deformation can be effectively avoided, and the diving phenomenon in the later stage of the battery cycle can be avoided, thereby improving the cycle performance of the battery. By making the central tube 3 include an outer tube 31 and a support structure 32, and making the support structure 32 include a support shaft 321 and a plurality of support springs 322 arranged on the support shaft 321, the purpose of reducing the diameter of the central tube is achieved by contracting the outer tube 31 and the support springs 322 when under pressure, and the purpose of restoring the diameter of the central tube to its original state is achieved by the rebound of the outer tube 31 and the support springs 322 when the pressure is reduced, so that the adjustment of the diameter of the central tube is achieved.

[0047] Of course, the above-mentioned replaceable implementations, as well as the replaceable implementations and the preferred implementations, can be used in a cross-coordinated manner to combine new implementations to suit more specific application scenarios.

[0048] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims of the present invention, any one of the claimed embodiments may be used in any combination.

[0049] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A central tube, characterized in that: The central tube is inserted into the central hole of the battery core and extends axially along the central hole. The central tube includes an outer tube and a support structure arranged in the outer tube. At least one of the outer tube and the support structure can adjust the diameter of the central tube.

2. The central tube according to claim 1, characterized in that The outer tube extends along the axial direction of the central hole, and the support structure is configured to adjust the diameter of the outer tube under the action of an external force.

3. The central tube according to claim 2, characterized in that The support structure includes a support shaft and at least one support spring arranged on the support shaft, the support shaft extends along the axial direction of the outer tube, and the support spring is arranged to adjust the distance between the support shaft and the inner wall of the outer tube under the action of external force.

4. The central tube according to claim 3, characterized in that There are multiple supporting springs, and there is a gap between two adjacent supporting springs. The supporting springs are extended and retracted along the radial direction of the central hole.

5. The central tube according to claim 4, characterized in that Along the axial projection of the central tube, the supporting spring piece is extended along the axial direction of the supporting shaft.

6. The central tube according to claim 4, characterized in that Along the radial projection of the central tube, the supporting spring piece is an arc-shaped structure or a spiral structure extending along the supporting axis toward the outer tube.

7. The central tube according to claim 2, characterized in that The wall thickness of the outer tube ranges from 0.2 mm to 1 mm.

8. The central tube according to claim 4, characterized in that The number of the supporting spring pieces is 4 to 12.

9. The central tube according to claim 3, characterized in that The supporting shaft is a solid structure.

10. A battery, characterized in that: The battery comprises a battery cell and a central tube as claimed in any one of claims 1 to 9.

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