Cathode collector plate and cylindrical lithium ion battery

Abstract

The utility model provides a negative collector plate and a cylindrical lithium ion battery. The negative collector plate comprises a plate body part, a supporting part, an elastic element and a contact part, the supporting part is connected with the disc body part, one end of the elastic element is connected to the supporting part, the other end of the elastic element extends out of the disc body part in the radial direction, the contact part is arranged outside the outer periphery of the disc body part and connected to the elastic element, and the contact part is provided with a contact surface used for being matched with the inner wall of a shell of the cylindrical lithium ion battery. The contact surface of the contact part can be well attached to the inner wall of the shell, so that the welding quality and the reliability of laser penetration welding between the negative electrode collector plate and the shell are good, and the risk of poor welding problems such as insufficient welding and solder skips of a welding wire between the negative electrode collector plate and the shell is low; due to the fact that the elastic force generated by the elastic element can enable the contact portion to be tightly attached to the inner wall of the shell, positioning and pressing tools do not need to be additionally arranged and used, welding equipment can be saved and simplified, and manufacturing cost is reduced.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a negative electrode current collector and a cylindrical lithium-ion battery. Background Technology

[0002] Currently, in large-diameter cylindrical lithium-ion batteries like the 46 series, the negative electrode current collector typically consists of a disk body and a flange around the perimeter of the disk body. During the assembly of the cylindrical lithium-ion battery, the disk body is welded to the negative terminal of the core, while the outer surface of the flange is bonded to the inner wall of the casing and connected via through-welding, thus enabling the casing and the core to conduct electricity. It is understandable that ensuring a good fit between the flange and the inner wall of the casing in the above process determines the reliability of subsequent welding.

[0003] To ensure a good fit between the inner and outer walls of the casing, related technologies typically employ clamping fixtures to press the flange against the inner wall, forming a reliable welded connection. However, even with clamping fixtures, a perfect fit between the flange and the inner wall is not guaranteed, leading to weld spalls, incomplete welds, and other defects, compromising weld reliability. Furthermore, the additional design of clamping fixtures and their corresponding positioning fixtures increases costs. Moreover, to accommodate these fixtures, the flange of the negative electrode current collector needs increased height, increasing its size and weight, thus reducing battery energy density. In addition, the aforementioned negative electrode current collector design is only suitable for cylindrical lithium-ion batteries of a specific size range and cannot be adapted to other battery sizes, further increasing manufacturing costs. Utility Model Content

[0004] This application provides a negative electrode current collector and a cylindrical lithium-ion battery to at least solve the technical problems of low welding reliability and high manufacturing cost of the negative electrode current collector to the casing in existing cylindrical lithium-ion batteries.

[0005] The first aspect of this application provides a negative electrode current collector that can be installed in the casing of a cylindrical lithium-ion battery, comprising:

[0006] Disc body;

[0007] The support portion is connected to the disk body portion;

[0008] An elastic element, one end of which is connected to the support portion, and the other end extends radially to the outer periphery of the disc body portion;

[0009] The contact portion is connected to one end of the elastic element that extends to the outer periphery of the disc portion. The contact portion has a contact surface on the side away from the disc portion, and the contact surface is used to fit and connect with the inner wall of the cylindrical lithium-ion battery casing.

[0010] The negative current collector according to the embodiments of this application has at least the following beneficial effects:

[0011] First, because the contact surface of the contact part can fit well with the inner wall of the shell, the laser penetration welding between the negative electrode current collector and the shell has good welding quality and high reliability, and the risk of welding defects such as incomplete welding or missing welding between the two is low.

[0012] Secondly, since the elastic force generated by the elastic element can make the contact part fit tightly against the inner wall of the shell, there is no need to set up and use additional positioning and clamping fixtures, which can save and simplify welding equipment and reduce manufacturing costs.

[0013] Furthermore, since no positioning and clamping fixtures are required for clamping, the height of the negative electrode current collector in the longitudinal direction can be reduced, thereby reducing the negative electrode current collector's occupation of the battery's longitudinal space, improving the utilization rate of the battery's internal space, and thus increasing the battery's capacity and energy density.

[0014] Furthermore, due to the action of the elastic element, the contact part can have a certain amount of expansion and contraction in the radial direction of the disk body. Thus, the negative electrode current collector can be adapted to various sizes of housings without changing its own size, thereby reducing design and manufacturing costs.

[0015] In one possible implementation, the elastic element comprises a helical spring with a length of L1, the length of which ranges from 0.8 to 2 mm.

[0016] By setting the length L1 of the helical spring within a reasonable range, it is possible to ensure that the welding effect of the disc body is taken into account while ensuring that the helical spring can generate an appropriate amount of deformation to press the contact part tightly against the inner wall of the housing.

[0017] In one possible implementation, the outer diameter of the helical spring is D, which ranges from 2 to 4 mm.

[0018] By setting the outer diameter D of the helical spring within a reasonable range, it is convenient to assemble the negative current collector with the housing, and it can be ensured that the helical spring can generate an appropriate amount of deformation to press the contact part against the inner wall of the housing.

[0019] In one possible implementation, the wire diameter of the helical spring is d, which ranges from 0.2 to 0.4 mm.

[0020] By setting the wire diameter d of the helical spring within a reasonable range, it is convenient to assemble the negative current collector with the housing, and it can be ensured that the helical spring can produce an appropriate amount of deformation to press the contact part against the inner wall of the housing.

[0021] In one possible implementation, the support portion and the contact portion are flush with each other along the height direction, and the support portion and the contact portion are arranged parallel to each other perpendicular to the disc body portion.

[0022] This design minimizes and lightens the dimensions of the structure consisting of the support, elastic element, and contact part in both the radial and vertical directions. It facilitates arrangement without affecting the welding effect of the disk body, and also does not increase the weight of the negative electrode current collector, thus ensuring that the energy density of the battery is not affected.

[0023] In one possible implementation, the elastic element is smaller in the height direction than the support portion and the contact portion, and the elastic element is located within the height range of the support portion and the contact portion.

[0024] By designing the height of the support, contact, and elastic elements within a reasonable range, the height of the negative current collector can be avoided from being too high, thus preventing it from occupying the internal space of the battery.

[0025] In one possible implementation, the support portion includes a flange that protrudes in the height direction along the outer periphery of the disc portion, and the contact portion includes a strip-shaped member that is curved in an arc.

[0026] By rationally designing the shape of the support and contact parts, the weight of the negative electrode current collector can be reduced while satisfying the welding effect and manufacturing costs can be lowered.

[0027] In one possible implementation, the height of the contact portion is L2, the distance from the bottom of the elastic element to the bottom of the disc portion is L3, and the range of L3 / L2 is 14≤L3 / L2≤28%.

[0028] By setting the relative positions of the elastic elements within a reasonable range, a good fit between the contact part and the inner wall of the housing can be ensured, facilitating penetration welding.

[0029] In one possible implementation, the number of contact portions is four, and the four contact portions are evenly distributed circumferentially along the outer periphery of the disk body portion.

[0030] By rationally designing the number and layout of the contact parts, when assembling the negative current collector with the housing, a pressing operation can be performed within the circumference of the housing to facilitate the installation of the negative current collector into the housing.

[0031] A second aspect of this application provides a cylindrical lithium-ion battery, including a casing, a winding core, and a negative electrode current collector as described in the first aspect embodiment above. The disk body portion of the negative electrode current collector is connected to the negative end of the winding core, and the contact portion of the negative electrode current collector is connected to the inner wall of the casing by laser penetration welding.

[0032] The cylindrical lithium-ion battery according to the embodiments of this application has at least the following beneficial effects:

[0033] The cylindrical lithium-ion battery of this application embodiment has the characteristics of good welding quality, low manufacturing cost and high energy density. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a cross-sectional schematic diagram of the negative electrode side of a cylindrical lithium-ion battery provided in an embodiment of this application;

[0036] Figure 2 This is a schematic diagram of the structure of a negative electrode current collector provided in an embodiment of this application;

[0037] Figure 3 yes Figure 2 A schematic diagram of the assembly of the negative current collector, the winding core, and the housing;

[0038] Figure 4 yes Figure 2 A front view of the negative current collector;

[0039] Figure 5 This is a schematic diagram of the structure of an elastic element in a negative electrode current collector provided in an embodiment of this application;

[0040] Figure 6 yes Figure 5 Schematic diagram of the lateral side of the elastic element;

[0041] Figure 7 yes Figure 5 A front view of the elastic element;

[0042] Figure 8 yes Figure 4 Schematic sectional view along the middle AA direction;

[0043] Figure 9 yes Figure 8 A partial schematic diagram at point B in the middle.

[0044] Figure label:

[0045] 100-Negative current collector, 110-Disc body, 111-Central hole, 112-Notch, 113-Circular edge, 114-Concave edge, 120-Flanged edge, 130-Elastic element, 140-Contact part, 141-Contact surface;

[0046] 200 - core, 210 - negative end;

[0047] 300 - Housing;

[0048] 400-Negative electrode cover. Detailed Implementation

[0049] The embodiments of this implementation are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this implementation, and should not be construed as limiting this implementation.

[0050] In the description of this embodiment, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this embodiment.

[0051] In the description of this embodiment, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0052] In the description of this embodiment, unless otherwise explicitly limited, terms such as setting, installing, and connecting should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this embodiment in conjunction with the specific content of the technical solution.

[0053] Figure 1 This is a cross-sectional schematic diagram of the negative electrode side of a cylindrical lithium-ion battery provided in an embodiment of this application. Figure 1 In a cylindrical lithium-ion battery, the negative electrode side is on top, and the positive electrode side is on the bottom. For example... Figure 1As shown, the cylindrical lithium-ion battery includes a negative electrode current collector 100, a core 200, a housing 300, and a negative electrode cover 400. The negative electrode end 210 of the core 200 is connected to the housing 300 via the negative electrode current collector 100, and the housing 300 serves as the negative electrode of the cylindrical lithium-ion battery. It can be understood that on the positive electrode side of the cylindrical lithium-ion battery (not shown in the figure), the positive electrode end of the core 200 is connected to the positive electrode cover assembly, which has an external electrode post serving as the positive electrode of the cylindrical lithium-ion battery.

[0054] It is understood that in the embodiments of this application, the negative electrode current collector 100 is connected to the inner wall of the housing 300 by laser penetration welding. However, by improving the structure of the negative electrode current collector 100, this application eliminates the need for additional positioning and clamping devices, thus enabling good surface-to-surface contact between the negative electrode current collector 100 and the inner wall of the housing 300. This results in higher welding reliability between the negative electrode current collector 100 and the housing 300 and reduces manufacturing costs. The negative electrode current collector 100 of this application embodiment is described in detail below.

[0055] Figure 2 This is a schematic diagram of the structure of the negative current collector 100 provided in the embodiments of this application, as shown below. Figure 2 As shown, the negative electrode current collector 100 includes a disk body 110, a support portion 120, an elastic element 130, and a contact portion 140. The support portion 120 is connected to the disk body 110. One end of the elastic element 130 is connected to the support portion 120, and the other end extends radially outward from the disk body 110. The contact portion 140 is located on the outer periphery of the disk body 110 and is connected to the end of the elastic element 130 extending outward from the disk body 110. Thus, the contact portion 140 is elastically connected to the support portion 120 via the elastic element 130. Furthermore, on the outer side of the contact portion 140, i.e., on the side away from the disk body 110, a contact surface 141 is provided that matches the inner wall surface of the housing 300. The contact surface 141 is used to fit and connect with the inner wall of the cylindrical lithium-ion battery housing, meaning the two can fit together.

[0056] It is understandable that when the contact portion 140 is subjected to a force toward the center of the disc portion 110, it can move along the radial direction of the disc portion 110 and continuously approach the center of the disc portion 110. During this process, the contact portion 140 can compress the elastic element 140, so that the elastic element 140 generates a reaction force on it.

[0057] Figure 3 yes Figure 2 A schematic diagram of the combined structure of the negative electrode current collector 100, the core, and the housing. In this state, the negative electrode current collector 100 can be welded to the housing 300 via laser penetration welding. Specifically, as shown... Figure 3 As shown, after the negative electrode current collector 100 is assembled with the core 200 and the housing 300, the bottom surface of the disk body 110 is welded to the negative end 210 of the core 200. The contact surface 141 of each contact part 140 is in contact with the inner wall of the housing 300. Furthermore, since the elastic element 140 exerts an elastic force on the contact part 140, the contact surface 141 is tightly in contact with the inner wall of the housing 300, and the two have a good fit.

[0058] It is understandable that the negative current collector 100 constructed as described above has several advantages, as follows:

[0059] First, since the contact surface 141 of the contact part 140 can fit well with the inner wall of the housing 300, the laser penetration welding between the negative electrode current collector 100 and the housing 300 has good welding quality and high reliability, and the risk of welding defects such as incomplete welding or missing welding between the two is low.

[0060] Secondly, since the elastic force generated by the elastic element 130 can make the contact part 140 fit tightly against the inner wall of the housing 300, there is no need to set up and use additional positioning and clamping fixtures, which can save and simplify welding equipment and reduce manufacturing costs.

[0061] Furthermore, since no positioning and clamping fixtures are required for clamping, the height of the negative electrode current collector 100 in the longitudinal direction can be reduced, thereby reducing the negative electrode current collector 100's occupation of the battery's longitudinal space, improving the utilization rate of the battery's internal space, and thus increasing the battery's capacity and energy density.

[0062] Furthermore, due to the action of the elastic element 130, the contact portion 140 can have a certain amount of expansion and contraction in the radial direction of the disk portion 110, so that the negative electrode current collector 100 can be adapted to various sizes of housing 300 without changing its own size, thereby reducing design and manufacturing costs.

[0063] like Figure 2 and Figure 4 As shown, the disk body 110 is the main structural part of the negative electrode current collector 100. It is a thin sheet and can be made of a metallic material, such as copper, which has good conductivity and solderability. The surface can be nickel-plated to improve corrosion resistance. A through-hole 111 is formed in the disk body 110, and multiple notches 112 are formed at the outer periphery of the disk body 110. It can be understood that the disk body 110 has two opposing disk surfaces, combined with... Figure 3The bottom plate is used for welding to the negative terminal 210 of the core 200, while the top plate faces the opening of the housing 300. It is understood that for a solution that injects electrolyte on the negative side, the electrolyte will enter the battery through this plate in the subsequent electrolyte injection process.

[0064] It is understandable that the cross-sectional shapes of the core 200 and the casing 300 of the cylindrical lithium-ion battery are both circular. Therefore, to facilitate welding between the disc portion 110 and the core 200, and to facilitate welding between the contact portion 140 and the casing 300, the outer contour shape of the negative electrode current collector 100 is generally circular. In this embodiment, due to the presence of the notch 112, the outer contour shape of the disc portion 110 is not a complete perfect circle. Figure 4 As can be seen, the shape of the disc body 110 is a closed shape composed of multiple alternating arc edges 113 and multiple concave edges 114 connected end to end.

[0065] Understandably, by setting the notch 112, on the one hand, during the electrolyte injection process, when the electrolyte flows into the disk surface of the disk body 110, some electrolyte will flow directly into the battery through the central hole 111, while some electrolyte will reach the outer periphery of the disk body 110 along the disk surface. Due to the existence of the notch 112, this part of the electrolyte will flow into the battery through the notch 112, improving the electrolyte injection efficiency, reducing the injection time, increasing production efficiency, and reducing the battery manufacturing cost. On the other hand, in the event of a short circuit or thermal runaway and a large amount of gas generation inside the battery, some gas can be diverted through the notch 112, improving the venting efficiency and enhancing the battery safety.

[0066] As mentioned above, the disc portion 110 is not a complete circle, but the ends of each arc-shaped edge 113 can be extended to form a complete circle. Therefore, the disc portion 110 can be regarded as a circular component.

[0067] Of course, this is not the only option. For example, the notch 112 can be omitted from the disc body 110, resulting in a perfectly circular shape. Multiple auxiliary holes can also be provided around the central hole 111 in the middle of the disc body to assist in liquid injection.

[0068] As previously described, the negative current collector 100 includes a support portion 120, which serves to mount and support the elastic element 130, and indirectly support the contact portion 140. It is understood that the support portion 120 is made of a metallic material, such as copper, which has good conductivity and weldability, and its surface can be nickel-plated to improve corrosion resistance. Furthermore, it is understood that the connection between the disk body 110 and the support portion 120 can be any fixed connection method. To ensure a stable connection, structural strength, and manufacturing economy, the disk body 110 and the support portion 120 can be integrally connected, for example, integrally formed by stamping.

[0069] In some embodiments, such as Figure 2 and Figure 3 As shown, the support portion 120 includes a flange protruding from the outer periphery of the disc body portion 110 toward the top disc surface. The flange is substantially perpendicular to the disc surface of the disc body portion 110. Furthermore, to avoid the location of the notch 112, the flange is only provided at the edge of the arcuate edge 113, meaning that there are multiple support portions 120. Thus, each flange appears to be a long, thin strip with an arcuate curve. Consequently, the outer side of the support portion 120 forms a mounting surface that extends a certain arc length along the circumferential direction of the outer periphery of the disc body portion 110, and the elastic element 130 can be connected to this mounting surface.

[0070] It is understandable that when multiple support parts 120 are provided, their number and position in the circumferential direction of the disk body 110 generally correspond to the number and position of the contact parts 140. For example, when there are 4 contact parts 140, there are also 4 support parts 120, and the 4 contact parts 140 and 4 support parts 120 are provided in a one-to-one correspondence.

[0071] Of course, it is not limited to this. For example, without the notch 112, the support portion 120 can be a single integral structure. In other words, in this case, only one support portion 120 can be provided. Furthermore, the shape of the support portion 120 is not limited to a flange; it can be any structure that can provide support. Moreover, its radial position along the disc portion 110 is not limited to the periphery of the disc portion 110.

[0072] As mentioned above, the negative electrode current collector 100 includes an elastic element 130. The function of the elastic element 130 is to support the contact portion 140 and generate elastic force to press the contact portion 140 against the inner wall of the housing 300. At the same time, the elastic element 130 also has a telescopic function, so that the contact portion 140 can move in the radial direction of the disk body portion 110, so that the negative electrode current collector 100 can be adapted to housings 300 of various sizes.

[0073] In some embodiments, such as Figure 5As shown, the elastic element 130 includes a helical spring. The elastic element 130 uses a helical spring, which has the advantages of simple structure and easy manufacturing. It can be made of stainless steel or spring steel, and its surface can be nickel-plated. Specifically, one end of the helical spring is connected to the support portion 120, and the other end is connected to the contact portion 140, thereby elastically connecting the contact portion 140 to the support portion 120. Furthermore, one end of the contact portion 140 extends radially outward from the outer periphery of the disc portion 110, thus suspending the contact portion 140 at the outer periphery of the disc portion 110. In this way, the helical spring expands or contracts radially in the disc portion 110 to facilitate insertion into a housing 300 of matching size. The restoring force of the helical spring presses the contact portion 140 against the inner wall of the housing 300, ensuring a good fit between its contact surface 141 and the inner wall of the housing 300. Understandably, the helical spring can be connected to the support 120 in any known manner, such as by welding, thereby forming a strong and reliable electrical connection between the two.

[0074] It is understandable that when the helical spring, which is the elastic element 130, is in a free state, the contact portion 140 can be considered to be in its initial position. At this time, the helical spring has not yet undergone elastic deformation. Therefore, the contact portion 140 connected to its end is furthest from the center of the disk portion 110. Thus, during the process of installing the negative current collector 100 into the housing 300, in order to smoothly enter the inner cavity of the housing 300, the helical spring needs to be compressed, causing the contact portion 140 to move from its initial position closer to the center of the disk portion 110. As a result, the position of the contact portion 140 will change, and the helical spring will also undergo compression deformation during this process, generating an elastic force in the opposite direction. This elastic force will cause the contact portion 140 to press against the inner wall of the housing 300, thereby ensuring that the contact surface 141 of the contact portion 140 fits well with the inner wall of the housing 300.

[0075] It is understandable that the number of elastic elements 130 corresponds to the number of contact portions 140. For example, when there are 4 contact portions 140, there are also 4 support portions 120. The 4 contact portions 140 and the 4 support portions 120 are arranged in a one-to-one correspondence.

[0076] In some embodiments, such as Figure 6 As shown, the length of the helical spring is L1, which ranges from 0.8 to 2 mm, i.e., 0.8 mm ≤ L1 ≤ 2 mm. For example, L1 is 1.1 mm. It should be noted that the length L1 of the helical spring described in this embodiment refers to the length of the helical spring in its free state, that is, the length of the negative electrode current collector 100 before it is assembled to the cylindrical lithium-ion battery. Figure 6The support portion 120 and the contact portion 140 connected to the helical spring are not shown in the figure.

[0077] Understandably, the space around the outer periphery of the negative electrode current collector 100 is limited, and the plate body 110 needs to have a reasonable plate area to facilitate connection with the core 200. If the helical spring is too long, it will be difficult to arrange. Conversely, if the helical spring is too short, its stroke will be too short, failing to generate sufficient deformation to achieve elastic deformation and thus failing to press the contact part 140 against the inner wall of the housing 300. By setting the length L1 of the helical spring within a reasonable range, the welding effect of the plate body 110 can be considered while ensuring that the helical spring can generate an appropriate amount of deformation to press the contact part 140 against the inner wall of the housing 300.

[0078] In some embodiments, such as Figure 7 As shown, the outer diameter of the helical spring is D, which ranges from 2 to 4 mm, i.e., 2 mm ≤ L1 ≤ 4 mm. For example, D is 3 mm.

[0079] Understandably, if the outer diameter of the helical spring is too large, its rigidity will be too strong, making it difficult to undergo elastic deformation. This increases the difficulty of installing the negative current collector 100 into the housing 300 and can easily lead to structural damage. Consequently, the contact part 140 may not be able to fully adhere to the inner wall of the housing 300, resulting in welding quality problems such as incomplete soldering or missing soldering. Conversely, if the outer diameter of the helical spring is too small, its rigidity and structural strength will be insufficient, and the helical spring will wobble, making installation difficult. It will also be impossible to ensure that the contact surface 141 of the contact part 140 can properly adhere to the inner wall of the housing 300, resulting in welding quality problems such as incomplete soldering or missing soldering. By setting the outer diameter D of the helical spring within a reasonable range, the assembly of the negative current collector 100 and the housing 300 is facilitated, and it can be ensured that the helical spring can generate an appropriate amount of deformation to press the contact part 140 tightly against the inner wall of the housing 300.

[0080] In some embodiments, such as Figure 7 As shown, the wire diameter of the helical spring is d, which ranges from 0.2 to 0.4 mm, i.e., 0.2 mm ≤ d ≤ 0.4 mm. For example, d is 0.3 mm.

[0081] Understandably, if the wire diameter of the helical spring is too large, its rigidity will be too high, making it difficult to undergo elastic deformation. This increases the difficulty of installing the negative current collector 100 into the housing 300 and can easily lead to structural damage. Consequently, the contact part 140 may not be able to fully adhere to the inner wall of the housing 300, resulting in welding quality problems such as incomplete soldering or missing solder joints. Conversely, if the wire diameter of the helical spring is too small, its rigidity and structural strength will be insufficient, and the helical spring will wobble, making installation difficult. It will also be impossible to ensure that the contact surface 141 of the contact part 140 can properly adhere to the inner wall of the housing 300, resulting in welding quality problems such as incomplete soldering or missing solder joints. By setting the range of the helical spring wire diameter d within a reasonable range, it is convenient to assemble the negative current collector 100 with the housing 300 and ensures that the helical spring can generate an appropriate amount of deformation to press the contact part 140 tightly against the inner wall of the housing 300.

[0082] Of course, it is not limited to this. The elastic element 130 can also adopt any other suitable structure, such as a silicone rubber component with good elastic properties.

[0083] As previously described, the negative electrode current collector 100 includes a contact portion 140 connected to one end of the elastic element 130 extending to the outer periphery of the disk body portion 110. It is understood that the contact portion 140 can be connected to the elastic element 130 in any known manner, such as by welding, thereby forming a strong and reliable conductive connection between them. The contact portion 140 serves to contact the inner wall of the housing 300 and is connected to the inner wall of the housing by through-welding to establish conductivity between them, thereby enabling an electrical connection between the housing 300 and the negative terminal 210 of the core 200, allowing the housing 300 to be used as the negative electrode of the battery. It is understood that the contact portion 140 is made of a metallic material, such as copper, which has good conductivity and weldability, and its surface can be nickel-plated to improve corrosion resistance.

[0084] In some embodiments, such as Figures 2 to 4 As shown, the contact portion 140 is an elongated strip-shaped member with an arc-shaped bend, which is substantially the same as the flange that serves as the support portion 120. The contact portion 140 is generally parallel to the flange. Thus, in the radial direction, it has an outer side away from the disc portion 110 and an inner side close to the disc portion 110. The contact portion 140 is connected to the elastic element 130 on the inner side. The contact portion 140 has an arc-shaped contact surface 141 formed on the outer side. It can be understood that the contact surface 141 matches the inner wall of the housing 300, so that when the contact portion 140 is pressed against the housing of the housing 300 by the elastic force, the contact surface 141 can fit tightly against the inner wall of the housing.

[0085] By setting the contact portion 140 as an arc-shaped, elongated sheet member, and setting the contact portion 140 parallel to the flange, and aligning the two in the height direction, the structure composed of the support portion 120, the elastic element 130, and the contact portion 140 is minimized and lightweight in both the radial and height directions. This facilitates arrangement without affecting the welding effect of the disk portion 110, and also does not increase the weight of the negative electrode current collector 100, thereby ensuring that the energy density of the battery is not affected.

[0086] Furthermore, such as Figure 8 As shown, the heights of the support portion 120 and the contact portion 140 are approximately the same, while the height of the elastic element 130 is less than the heights of the support portion 120 and the contact portion 140, and is located within the height range of the support portion 120 and the contact portion 140. For example, taking the contact portion 140 as an example, it is a long strip-shaped sheet member. Therefore, the distance from the top to the bottom in its height direction is the height of the contact portion 140. It can be understood that this height direction is consistent with the thickness direction of the disk portion 110. In this way, by designing the heights of the support portion 120 and the contact portion 140 within a reasonable range, the height of the negative electrode current collector 100 can be avoided from being too high, thus preventing it from occupying the internal space of the battery.

[0087] Furthermore, with the height of the contact portion 140 as L2 and the distance from the bottom of the elastic element 130 to the bottom of the disc portion 110 as L3, the range of L3 / L2 is 14≤L3 / L2≤28%. For example, the height of the contact portion 140, L2, is 4.5mm, L3 is 0.85mm, and L3 / L2 is 18.9%.

[0088] Understandably, if the elastic element 130 is far from the bottom of the disk body 110, i.e., the position of the elastic element 130 is too high, then during the process of installing the negative electrode current collector 100 into the housing, the force of the inner wall of the housing pressing on the contact part 140 is transmitted to the end of the support part 120 away from the root, i.e., the top end of the support part 120. Since this position is prone to bending deformation, the contact part 140 cannot fit well with the inner wall of the housing 300. The welding quality of the two is difficult to guarantee, and there is a high risk of quality problems such as poor welding and missing welding in the welding line. It may even lead to the collapse of the entire structure and the generation of scrap. Conversely, if the elastic element 130 is too close to the bottom of the disk portion 110, i.e., the elastic element 130 is positioned too low, then the elastic element 130 cannot support most of the upper area of ​​the contact portion 140. Consequently, the upper area of ​​the contact portion 140 will tilt during the insertion of the negative electrode current collector 100 into the housing. Furthermore, after the contact portion 140 is pressed against the inner wall of the housing 300, the upper part of the contact portion 140 lacks strong support due to the elastic element 130's proximity to the root of the support portion 120. This limits the range of possible solder joint positions during welding. In this case, welding in the upper area is more prone to problems such as incomplete soldering or missed soldering. It should be noted that the "root" described here refers to the connection point between the support portion 120 and the disk portion 110, i.e., the bottom of the flange. By setting the relative position of the elastic element 130 within a reasonable range, a good fit between the contact portion 140 and the inner wall of the housing 300 can be ensured, facilitating through-welding.

[0089] It is understandable that multiple contact portions 140 can be provided, for example, four contact portions 140, and the four contact portions 140 are evenly distributed along the circumferential direction of the outer periphery of the disk portion 110. In this way, a pressing operation can be performed within the circumferential range of the housing 300 to facilitate the installation of the negative electrode current collector 100 into the housing 300. It is also understandable that the number of support portions 120 and elastic elements 130 can be matched one-to-one with the number of contact portions 140, thereby ensuring the installation and welding effect while reducing manufacturing costs.

[0090] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this implementation. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0091] Although embodiments of this implementation have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this implementation, the scope of which is defined by the claims and their equivalents.

Claims

1. A negative electrode current collector, characterized in that, include: Disc body (110); The support part (120) is connected to the disk body part (110); The elastic element (130) has one end connected to the support portion (120) and the other end extending radially to the outer periphery of the disc portion (110); The contact portion (140) is connected to one end of the elastic element (130) that extends to the outer periphery of the disc portion (110). The contact portion (140) has a contact surface (141) on the side away from the disc portion (110). The contact surface (141) is used to fit and connect with the inner wall of the cylindrical lithium-ion battery casing. The support portion (120) and the contact portion (140) are flush with each other in the height direction, and the support portion (120) and the contact portion (140) are arranged parallel to each other perpendicular to the disc portion (110). The support portion (120) includes a flange that protrudes in the height direction along the outer periphery of the disc portion (110), and the contact portion (140) includes a strip-shaped member that is curved in an arc. The elastic element (130) is smaller in height than the support portion (120) and the contact portion (140), and the elastic element (130) is located within the height range of the support portion (120) and the contact portion (140).

2. The negative electrode current collector according to claim 1, characterized in that, The elastic element (130) includes a helical spring with a length of L1, which ranges from 0.8 to 2 mm.

3. The negative electrode current collector according to claim 2, characterized in that, The outer diameter of the helical spring is D, which ranges from 2 to 4 mm.

4. The negative electrode current collector according to claim 2, characterized in that, The diameter of the helical spring is d, which ranges from 0.2 to 0.4 mm.

5. The negative electrode current collector according to claim 1, characterized in that, The height of the contact portion (140) is L2, and the distance from the bottom of the elastic element (130) to the bottom of the disc portion (110) is L3. The range of L3 / L2 is 14≤L3 / L2≤28%.

6. The negative electrode current collector according to any one of claims 1 to 4, characterized in that, The number of the contact portions (140) is four, and the four contact portions (140) are evenly distributed along the circumferential direction of the outer periphery of the disk body portion (110).

7. A cylindrical lithium-ion battery, characterized in that, The device includes a housing (300), a core (200), and a negative electrode current collector (100) according to any one of claims 1-6, wherein the disk body portion (110) of the negative electrode current collector (100) is connected to the negative end (210) of the core (200), and the contact portion (140) of the negative electrode current collector (100) is connected to the inner wall of the housing (300) by laser penetration welding.

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