Rechargeable batteries, battery packs, and electronic devices

Abstract

The present invention provides a secondary battery, battery pack, and electronic device that can improve the problem of low electrolyte penetration efficiency. [Solution] The secondary battery includes a housing, an electrode assembly, and a current collector. The electrode assembly includes a wound structure formed by stacking and winding a first electrode sheet, a second electrode sheet, and a separator. The end of the first electrode sheet includes an uncoated area including a first cut segment and an uncut segment. The uncut segment is folded to form a tab, and the first cut segment is wound to form a first annular region. The area covered by the tab is a second annular region, and the first annular region includes a third annular region not covered by the second annular region. The current collector is welded to the tab, and the current collector includes a second injection hole. Here, when projected along the axial direction of the electrode assembly, the projection of the second injection hole covers the third annular region.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to secondary batteries, battery packs, and electronic devices.

Background Art

[0002] Cylindrical batteries have advantages such as high energy efficiency and long cycle life, and thus have been widely applied in many aspects of modern society. The electrode assembly usually has a wound structure, tabs are installed at both ends of the electrode assembly, and a current collector member is electrically connected to the outside of the tabs. Due to the shielding of the current collector member and the tabs, it brings great problems to the injection of electrolyte and the infiltration of the electrode assembly in the manufacturing process of the cylindrical battery. Therefore, not only the production efficiency of the cylindrical battery is limited, but it also affects the performance of the battery. Therefore, improving the infiltration efficiency of the electrolyte has become a technical problem to be overcome in this field.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The present invention provides a secondary battery, a battery pack, and an electronic device that can improve the technical problem of low infiltration efficiency of the electrolyte.

Means for Solving the Problems

[0004] To achieve the aforementioned and other related objectives, the present invention provides a secondary battery, a battery pack, and an electronic device. The secondary battery includes a housing, an electrode assembly, and a current collector. The housing includes an end wall on which a first injection hole is provided. The electrode assembly is housed within the housing and includes a winding structure formed by stacking and winding a first electrode sheet, a second electrode sheet, and a separator. The end of the first electrode sheet includes an uncoated region protruding from the separator along the axial direction of the electrode assembly, the uncoated region including a first cut segment near the winding axis of the winding structure and an uncut segment located radially outward of the first cut segment. The uncut segment of the uncoated region is bent to form a tab. Along the radial direction of the electrode assembly, the first cut segment is wound to form a first annular region. The region covered by the tab is a second annular region, and the first annular region includes a third annular region not covered by the second annular region. The current collector is positioned between the electrode assembly and the end wall and is welded to the tab. The current collector includes a second fluid injection hole. Here, when projected onto the end face of the winding structure along the axial direction of the electrode assembly, the projection of the second fluid injection hole covers a third annular region.

[0005] In the above-described technical solution, the first cut segment of the uncoated region is wound to form a first annular region, the uncut segment of the uncoated region is folded to form a tab, the region covered by the tab is a second annular region, and the first annular region includes a third annular region not covered by the second annular region. That is, the third annular region is exposed outside the second annular region and is not shielded by the tab. Furthermore, the projection of the second injection hole of the current collector member covers the third annular region. Because the projection of the second injection hole covers the third annular region, i.e., the third annular region is exposed inside the second injection hole, the third annular region is not shielded by either the tab or the current collector member. Therefore, when electrolyte is injected from the first injection hole, the electrolyte flows directly into the third annular region exposed inside the second injection hole. In the process of flowing in, the electrolyte is directly absorbed by the separator of the third annular region and penetrates radially, allowing it to permeate the electrode assembly. This installation improves the immersion efficiency of the electrode assembly, and simultaneously, by positioning the third annular region to surround the winding axis of the winding structure, the uniformity of electrolyte immersion along the radial direction of the electrode assembly can be improved, thereby improving the performance and lifespan of the battery.

[0006] Furthermore, the current collector and the tab are welded together. Since there is no tab on the third annular region, exposing the third annular region to the second injection hole effectively prevents accidental welding within the third annular region when welding the current collector and the tab, thereby reducing the risk of the separator burning out.

[0007] In one embodiment of the secondary battery of the present invention, the projection of the second liquid injection hole covers the first annular region.

[0008] In the above-described technical solution, the first annular region is formed by winding the first cut segment. After cutting, part of the first annular region is covered by a tab, but compared to the uncut segment, the area covered by the tab is still convenient for electrolyte flow, and the electrolyte can flow in through the gap between the tab and the first annular region. In addition, the electrolyte is directly absorbed into the separator of the first annular region during the flow process and penetrates radially, allowing it to infiltrate the electrode assembly. With this setup, the entire first annular region can be exposed into the second injection hole, further improving the infiltration efficiency of the electrode assembly.

[0009] At the same time, the portion of the first annular region covered by the tabs has a relatively small number of tab layers and is not suitable for welding to the current collector. By exposing the entire first annular region into the second injection hole, it is possible to effectively prevent accidental welding to the area with a small number of tab layers when welding the current collector and the tabs, thereby reducing the risk of the tabs melting off and the separator burning out.

[0010] In one embodiment of the secondary battery of the present invention, the inner radius of the second annular region is R1, and the winding structure includes a winding hole located at the center, the radius of which is R2, where R1-R2≧1mm.

[0011] In the above-described technical solution, the inner circumference of the second annular region is, that is, the inner circumference of the region covered by the tab. By limiting R1-R2 ≥ 1 mm, it is possible to have an annular region on the outer circumference of the winding hole that is not shielded by the tab and has a width of at least 1 mm, and this annular region is, that is, the third annular region. This configuration ensures that the width of the third annular region is not less than 1 mm, thereby further improving the penetration efficiency of the electrode assembly, and thereby improving the performance and lifespan of the battery.

[0012] In one embodiment of the secondary battery of the present invention, when projected onto the end face of the winding structure along the axial direction of the electrode assembly, the projected area of ​​the current collector is S1, and the end face area of ​​the winding structure is S2, where 0.9S2 ≥ S1 ≥ 0.4S2.

[0013] In the above-described technical solution, setting S1≧0.4S2 ensures that the area for welding the current collector to the tab is sufficiently large, thereby improving the hardness and reliability of the weld between the current collector and the electrode assembly, as well as the effect of reducing the internal resistance of the battery. Setting S1≦0.9S2 ensures that the area of ​​the electrode assembly that is not shielded by the current collector and is exposed to the outside is 0.1S2 or more. This installation is advantageous on the one hand for allowing the electrolyte to penetrate smoothly into the electrode assembly through the unshielded area, and on the other hand for allowing gases inside the electrode assembly to be discharged from the unshielded area, thereby improving the safety performance and overall performance of the battery.

[0014] In one embodiment of the secondary battery of the present invention, the current collector member includes a plurality of tab connectors arranged circumferentially, with one transition connector provided between each pair of adjacent tab connectors, and at least one through-hole provided on each transition connector. Along the radial direction of the current collector member, the maximum width of the through-hole is L, and the radius of the winding structure is R3, where L ≥ 0.5 × (R3 - R2).

[0015] In the above-described technical solution, the through-holes installed in the transition connection section may be one or multiple. The above-described through-holes are, in other words, the parts of the current collector member that do not shield the electrode assembly, and R3-R2 corresponds to the annular width of the end face of the winding structure, and is further limited to L≧0.5×(R3-R2). That is, the maximum value of the width of one through-hole or the sum of the widths of multiple through-holes in the same transition connection section is not less than 0.5 times the annular width of the end face of the winding structure. This arrangement allows the electrolyte to permeate into the electrode assembly from the through-holes, thereby improving the electrolyte permeation efficiency. At the same time, by arranging multiple transition connection sections along the circumferential direction of the current collector member and spacing adjacent transition connection sections with tab connection sections, the through-holes can be arranged even more uniformly along the circumferential direction of the current collector member. This arrangement can further improve the uniformity of electrolyte permeation and, furthermore, improve the performance and lifespan of the battery.

[0016] In one embodiment of the secondary battery of the present invention, the current collector includes a plurality of tab connections arranged circumferentially, with one transition connection provided between each pair of adjacent tab connections. The maximum distance from the outer edge of the transition connection to the center of the current collector is R4, and the radius of the winding structure is R3, where R3 > R4.

[0017] In the above-described technical solution, the distance from the outer edge of the transition connection to the center of the first current collector is smaller than the outer edge radius of the winding structure. This installation further reduces shielding of the electrode assembly by the current collector, thereby improving the electrolyte penetration efficiency and, furthermore, the performance and lifespan of the battery. In addition, it prevents the current collector from interfering with the electrode assembly when it is attached to the housing, thereby improving assembly efficiency and assembly quality.

[0018] In one embodiment of the secondary battery of the present invention, the uncoated region further includes a second cut segment located on the outer circumference of the winding structure and adjacent to the uncut segment. Along the radial direction of the electrode assembly, the second cut segment is wound to form a fourth annular region, the inner peripheral radius of the fourth annular region being R5, where R4 ≤ R5.

[0019] In the above-described technical solution, the fourth annular region formed by winding the second cut segment is not shielded by the tab, and the fourth annular region is positioned on the outer circumference of the winding structure. At the same time, by limiting R4 ≤ R5, that is, by making the distance from the outer circumference of the transition connection to the center of the first current collector less than or equal to the inner circumference radius of the fourth annular region, the portion of the fourth annular region located radially outside the transition connection is also not shielded by the current collector. Therefore, when electrolyte is injected from the first injection hole, the electrolyte flows directly into the portion exposed to the outside of the fourth annular region. In the process of inflow, the electrolyte is directly absorbed into the separator of the fourth annular region and penetrates simultaneously in the circumferential and radial directions, allowing it to permeate the electrode assembly. This configuration improves the permeation efficiency of the electrode assembly, and at the same time, by positioning the portion of the fourth annular region not covered by the current collector along the circumferential direction of the current collector, the uniformity of electrolyte permeation along the radial direction of the electrode assembly can be improved, thereby improving the performance and lifespan of the battery.

[0020] In one embodiment of the secondary battery of the present invention, along the axial direction of the current collector, the current collector covers at least a portion of the tab located on the outermost periphery of the winding structure.

[0021] In the above-described technical solution, by covering and pressing down at least a portion of the tab located on the outermost circumference of the winding structure with a current collector, the tab can be effectively prevented from lifting up, thereby reducing the risk of a short circuit caused by the tab breaking due to external force and falling into the housing.

[0022] In one embodiment of the secondary battery of the present invention, R3 - R4 ≥ 1 mm.

[0023] In the above technical solution, by further limiting R3 - R4 ≥ 1 mm, the transition connection part can press and cover as many tabs on the outermost periphery as possible. At the same time, it can also ensure that the area not shielding the electrode assembly becomes larger. Therefore, the risk of the tab breaking due to the action of an external force and falling inside the housing can be reduced, and the effect of improving the infiltration efficiency of the electrolyte can also be realized.

[0024] In one embodiment of the secondary battery of the present invention, when projected onto the end face of the winding structure along the axial direction of the electrode assembly, the projection of the first liquid injection hole covers at least a part of the third annular region covered by the projection of the second liquid injection hole.

[0025] In the above technical solution, by the projection of the first liquid injection hole covering at least a part of the third annular region covered by the projection of the second liquid injection hole, when the electrolyte enters from the first liquid injection hole, it can directly flow into the parts of the tab and the current collecting member in the third annular region that are not shielded. Therefore, the electrolyte can be directly absorbed by the separator in the third annular region and penetrate radially to infiltrate the electrode assembly. With this arrangement, the infiltration efficiency of the electrode assembly can be further improved.

[0026] The present invention further provides a battery pack, which includes the secondary battery according to any one of the above items.

[0027] The present invention further provides an electronic device, which includes the above battery pack.

Effects of the Invention

[0028] The secondary battery of the present invention forms a first annular region by winding the first cut segment of the uncoated region, and forms a tab by bending the uncut segment of the uncoated region. The region covered by the tab is the second annular region, and the first annular region includes a third annular region not covered by the second annular region. That is, the third annular region is exposed outside the second annular region and is not shielded by the tab. Further, the projection of the second liquid injection hole of the current collecting member covers the third annular region. By covering the third annular region with the projection of the second liquid injection hole, that is, by exposing the third annular region in the portion of the second liquid injection hole, the third annular region can be made not shielded by the tab or the current collecting member. Therefore, when the electrolytic solution is injected from the first liquid injection hole, the electrolytic solution directly flows into the third annular region exposed in the second liquid injection hole. In the process of flowing in, the electrolytic solution is directly absorbed by the separator in the third annular region and penetrates in the radial direction, so that the electrode assembly can be infiltrated. By this arrangement, the infiltration efficiency of the electrode assembly can be improved. At the same time, by arranging the third annular region so as to surround the winding axis of the winding structure, the uniformity of the electrolytic solution infiltration along the radial direction of the electrode assembly can be improved, thereby improving the performance and life of the battery.

[0029] Also, the current collecting member and the tab are connected by welding. Since there is no tab in the third annular region, by exposing the third annular region in the second liquid injection hole, it is possible to effectively prevent miswelding in the third annular region when welding the current collecting member and the tab, and reduce the risk of the separator burning out.

Brief Description of the Drawings

[0030] To more clearly explain the embodiments of the present invention or the technical solutions of the prior art, the attached drawings necessary for the description of the embodiments or the prior art are briefly introduced below. Obviously, the attached drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative efforts.

[0031] [Figure 1] It is a schematic structural view of one embodiment of the secondary battery of the present invention. [Figure 2] This is a cross-sectional view of an electrode assembly in one embodiment of the secondary battery of the present invention. [Figure 3] This is a schematic diagram of the exploded structure of the electrode assembly and the first current collector in one embodiment of the secondary battery of the present invention. [Figure 4] This is a localized enlarged view of section A in Figure 3. [Figure 5] This is a top view of an electrode assembly and a first current collector in one embodiment of the secondary battery of the present invention. [Figure 6] This is a schematic diagram of the structure of the first uncoated region of the electrode assembly in one embodiment of the secondary battery of the present invention. [Figure 7] This is a schematic diagram of one embodiment of the battery pack of the present invention. [Figure 8] This is a schematic diagram of one embodiment of the electronic device of the present invention. [Modes for carrying out the invention]

[0032] The embodiments of the present invention will be described below through specific examples, but those skilled in the art will readily understand other advantages and effects of the present invention from what is disclosed herein. The present invention may also be implemented or applied through other different specific embodiments, and the details of each item herein can be modified or changed in various ways based on different viewpoints and applications, as long as they do not deviate from the spirit of the invention. It should be noted that the embodiments and features within the embodiments below may be combined with each other, where there is no contradiction. It should also be understood that the technical terms used in the embodiments of the present invention are for the purpose of describing specific embodiments and do not limit the scope of protection of the present invention. In the following embodiments, test methods for which specific conditions are not specified shall generally follow conventional conditions or conditions proposed by various manufacturers.

[0033] Where numerical ranges are given in embodiments, it should be understood that, unless otherwise specifically described in the Invention, any two endpoints of each numerical range and any number between those two endpoints can be selected. Unless otherwise specifically defined, all technical and scientific terms used in the Invention may be based on prior art knowledge of those skilled in the art and the description of the Invention. Furthermore, the Invention may also be carried out using any prior art methods, apparatus, and materials that are similar to or equivalent to those described in embodiments of the Invention.

[0034] It should be noted that terms such as “up,” “down,” “left,” “right,” “middle,” and “one” used herein are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes or adjustments to their relative relationships should also be considered within the scope of the invention, provided that there is no substantial change in the technical content.

[0035] A secondary battery includes a housing and an electrode assembly. The electrode assembly is housed within the housing and is the component in the secondary battery where electrochemical reactions occur. One or more electrode assemblies may be included within the housing.

[0036] Electrode assemblies are primarily formed by winding or laminating positive electrode sheets and negative electrode sheets, usually with a separator between them. The positive electrode sheet includes a positive electrode current collector and positive electrode active material, the positive electrode active material being coated onto the surface of the positive electrode current collector. The positive electrode current collector includes a coated area where the active material is applied and an uncoated area where the active material is not applied, the uncoated area forming the positive electrode tab of the electrode assembly after winding. The negative electrode sheet includes a negative electrode current collector and negative electrode active material, the negative electrode active material being coated onto the surface of the negative electrode current collector. The negative electrode current collector includes a coated area where the active material is applied and an uncoated area where the active material is not applied, the uncoated area forming the negative electrode tab of the electrode assembly after winding. Taking a lithium-ion secondary battery as an example, the material of the positive electrode current collector may be aluminum, and the positive electrode active material layer may contain a positive electrode active material, which may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The material of the negative electrode current collector may be copper, and the negative electrode active material layer may contain a negative electrode active material, which may be carbon or silicon. The material of the separator may be polypropylene (PP) or polyethylene (PE), etc. To provide protection and insulation to the battery cell, the outside of the battery cell may be covered with an insulating film, which can be synthesized from PP, PE, PET, PVC, or other polymer materials.

[0037] The housing includes a first end wall and a second end wall that are positioned relative to each other, and a side wall surrounding the first and second end walls. One end of the side wall has an opening, and the electrode assembly can be assembled inside the housing through the opening. A first injection hole is provided on the first or second end wall for injecting the electrolyte into the housing.

[0038] The tabs at both ends of the electrode assembly are welded to the current collectors. The current collectors can optimize the collection and distribution of current in the electrode assembly, thereby improving the performance of the battery.

[0039] However, the inventors discovered that when the electrolyte is injected, the current collector partially obstructs the penetration of the electrolyte into the electrode assembly. In addition, the bent structure of the tab also partially obstructs the penetration of the electrolyte, reducing the efficiency of electrolyte infiltration, limiting the production efficiency of the battery, and affecting the performance of the battery. Therefore, improving the efficiency of electrolyte infiltration is extremely necessary and urgent.

[0040] In view of this, the present invention provides one technical solution. A first annular region is formed by winding a first cutting segment on the side of the uncoated region closer to the winding axis, and the first annular region includes a third annular region that is not covered by a tab. Furthermore, the projection of the second liquid injection hole of the current collector member covers the third annular region, and the third annular region covered by the projection of the second liquid injection hole is, in other words, the third annular region exposed into the second liquid injection hole. Since the third annular region is not shielded by either the tab or the current collector member, when electrolyte is injected from the first liquid injection hole, the electrolyte is directly absorbed into the separator of the third annular region during the inflow process and penetrates radially, allowing it to permeate the electrode assembly, thereby improving the permeation efficiency of the electrode assembly.

[0041] Referring to Figures 1 to 8, the present invention provides a secondary battery 100, which includes a housing 110, an electrode assembly 120, an electrode post 130, and a current collector.

[0042] Referring to Figure 1, the housing 110 includes end walls, on which the first injection hole 115 is located. More specifically, in this embodiment, the housing 110 includes a first end wall 114 and a second end wall 111 located relative to each other, and a side wall 112 surrounding the first end wall 114 and the second end wall 111. The first injection hole 115 can be located on the first end wall 114 or on the second end wall 111, and the shape of the first injection hole 115 may be circular, ring-shaped, petal-shaped, rectangular, elliptical, polygonal, or other irregular shape. Typically, a sealing cover of a suitable size is further installed over the first injection hole 115 to close it after the injection is complete, but the present invention is not limited thereto, and it is sufficient as long as the first injection hole 115 can be sealed and closed.

[0043] Referring to Figure 1, the connections between the first end wall 114 and the side wall 112, and between the second end wall 111 and the side wall 112, can be achieved in various ways, such as by integral press molding, integral casting, or split welding, provided that a stable sealing and electrical connection relationship can be formed. The method of surrounding the side wall 112 is not limited and may be cylindrical or prismatic, or it may be surrounded along any other closed-loop contour that coincides with the first end wall 114 and the second end wall 111. In one embodiment, the outer edges of the first end wall 114 and the second end wall 111 of this embodiment are circular, and the side wall 112 cylindrically surrounds the outer edges of the first end wall 114 and the second end wall 111. The second end wall 111 and the side wall 112 are integrally molded, and a circular opening 113 is formed at one end of the side wall 112 near the first end wall 114. In some embodiments, the electrolyte can be injected through the opening 113 described above. A housing chamber is formed within the housing 110, which is enclosed by the second end wall 111 and the side wall 112, and is used to house the electrode assembly 120, electrolyte, and other necessary battery components. Specifically, the diameter of the housing 110 can be determined based on the specific size of the electrode assembly 120, and may be, for example, 18 mm, 21 mm, 46 mm, etc. The material of the housing 110 may be of various types, for example, copper, iron, aluminum, steel, aluminum alloy, etc. To prevent the housing 110 from rusting during long-term use, a layer of rust-preventive material such as metallic nickel may be plated onto the surface of the housing 110.

[0044] Referring to Figures 1 and 2, the electrode assembly 120 is housed within the housing 110 and is a component in the secondary battery 100 where an electrochemical reaction occurs. One or more electrode assemblies 120 may be included within the housing 110. The electrode assembly 120 includes a winding structure 126 formed by stacking and winding a first electrode sheet 123, a second electrode sheet 121, and a separator 122, wherein the first electrode sheet 123 and the second electrode sheet 121 have opposite polarities. In some embodiments, the first electrode sheet 123 is the positive electrode sheet and the second electrode sheet 121 is the negative electrode sheet, while in some other embodiments, the first electrode sheet 123 is the negative electrode sheet and the second electrode sheet 121 is the positive electrode sheet.

[0045] Referring to Figures 2 and 6, in this embodiment, the first electrode sheet 123 is a negative electrode sheet, and the first electrode sheet 123 includes a negative electrode current collector 1231 and a negative electrode active material, the negative electrode active material being coated on the surface of the negative electrode current collector 1231. The negative electrode current collector 1231 includes a first coated region 1232 to which the active material is coated and an uncoated region to which the active material is not coated. For ease of distinction, the uncoated region on the first electrode sheet 123 is defined as the first uncoated region 1233. The first uncoated region 1233 protrudes from the separator 122 along the axial direction of the electrode assembly 120, the first uncoated region 1233 is located at the end of the first electrode sheet 123, and the first uncoated region 1233 includes a first cut segment 12331 close to the winding axis of the winding structure 126 and an uncut segment 12332 located radially outward of the first cut segment 12331. The uncut segment 12332 of the first uncoated region 1233 is folded to form a tab. For ease of distinction, the tab on the first electrode sheet 123 is defined as the first tab 124, and the first tab 124 is the corresponding negative electrode tab. Along the radial direction of the electrode assembly 120, the first cut segment 12331 is wound to form the first annular region 1241, the tab-covered region being the second annular region 1242, and the first annular region 1241 includes a third annular region 1243 that is not covered by the second annular region 1242.

[0046] By installing the first cut segment 12331 described above, on the one hand, the situation in which interference occurs near the winding axis when the first uncoated region 1233 is bent can be improved, and on the other hand, the first annular region 1241 includes a third annular region 1243 that is not covered by the second annular region 1242, that is, the third annular region 1243 is exposed outside the second annular region 1242 and is not shielded by the tab, so the electrolyte is directly absorbed by the separator 122 of the third annular region 1243 in the process of flowing in and penetrates radially, allowing the electrode assembly 120 to be permeated. This installation can improve the permeation efficiency of the electrode assembly 120.

[0047] Referring to Figures 2 and 6, the second electrode sheet 121 is the positive electrode sheet. Specifically, the second electrode sheet 121 includes a positive electrode current collector 1211 and a positive electrode active material, the positive electrode active material being coated onto the surface of the positive electrode current collector 1211. The positive electrode current collector 1211 includes a second coated region 1212 on which the active material is coated and a second uncoated region 1213 on which the active material is not coated, the second uncoated region 1213 located at the end of the second electrode sheet 121. The second uncoated region 1213 protrudes from the separator 122 along the other axial end of the electrode assembly 120 and is bent toward the winding axis to form a second tab 125. The second tab 125 is the corresponding positive electrode tab. It should be noted that the second uncoated region 1213 and the first uncoated region 1233 may both have the first cutting segment 12331 installed, or the first cutting segment 12331 may be installed only in the region closer to the electrolyte inlet of the first uncoated region 1233 and the second uncoated region 1213, but the present invention is not limited thereto.

[0048] Referring to Figures 1 and 2, the separator 122 is placed between the first electrode sheet 121 and the second electrode sheet 123, separating the positive electrode active material layer from the negative electrode active material layer. Taking the lithium-ion secondary battery 100 as an example, the material of the positive electrode current collector 1211 may be aluminum, and the positive electrode active material layer contains positive electrode active material, which may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The material of the negative electrode current collector 1231 may be copper, and the negative electrode active material layer contains negative electrode active material, which may be carbon or silicon, etc. The substrate material of the separator 122 may be polypropylene (PP) or polyethylene (PE), etc. To provide protection and insulation to the battery cell, the outside of the battery cell may be covered with an insulating film, which can be synthesized from PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC), or other polymer materials.

[0049] Referring to Figures 1 and 2, the first tab 124 further faces the first end wall 114 or the second end wall 111, and the second tab 125 faces the other end of the housing 110. In this embodiment, the second tab 125 faces the second end wall 111 and is electrically connected to the pole 130 to charge the pole 130 positively. The first tab 124 faces the first end wall 114 and electrically connects the housing 110 to the first tab 124 to charge it negatively. However, in other embodiments, the first tab 124 may be connected to the pole 130 and the second tab 125 may be connected to the housing 110.

[0050] Referring to Figures 1 and 2, the current collector is further positioned between the electrode assembly 120 and the end wall and welded to the tab. For ease of distinction and understanding, the current collector electrically connected to the first tab 124 is referred to as the first current collector 140, and the current collector electrically connected to the second tab 125 is referred to as the second current collector 150. The welding method can be ultrasonic welding, resistance welding, laser welding, etc., but the present invention is not limited thereto. In this embodiment, the first current collector 140 is located between the first end wall 114 and the first tab 124. The first tab 124 is the negative electrode tab, and it is preferable to select copper metal as the material for the first current collector 140. The second current collector 150 is located between the second end wall 111 and the second tab 125. The second tab 125 is the positive electrode tab, and it is preferable to select aluminum metal as the material for the second current collector 150. It should be noted that the shapes of the first current collector 140 and the second current collector 150 may be any rotationally symmetric shape, such as a circle, square, regular polygon, petal shape, or other geometric shapes that have a center of symmetry and can overlap with the original shape after being rotated by a certain angle around the center of symmetry. However, the present invention is not limited thereto, as long as a stable and reliable electrical connection relationship can be achieved. The centers of the first current collector 140 and the second current collector 150 are, in other words, their own centers of symmetry. To improve the positioning, ease of processing, interchangeability, and uniformity of the current collectors in the installation process, both the first current collector 140 and the second current collector 150 in this embodiment employ a circular structure.

[0051] Referring to Figures 1 and 2, the pole post 130 penetrates the second end wall 111 and is insulated from the second end wall 111. The structural form of the pole post 130 may be any suitable form that can penetrate the second end wall 111 and be electrically connected to the first electrode sheet 123 or the second electrode sheet 121, for example, the cross section may be circular, square, prismatic, or a different contour that can achieve stable conductivity. One end of the pole post 130 facing the electrode assembly 120 is electrically connected directly or indirectly to the first tab 124 or the second tab 125 by penetrating the second end wall 111. For example, the pole post 130 may be indirectly electrically connected to the second electrode sheet 121 via a current collector. The other end of the pole post 130 away from the electrode assembly 120 is exposed to the outside of the housing 110 and forms the corresponding electrode. The electrical character of the pole post 130 may be positive or negative. For example, in one embodiment, the pole post 130 is electrically connected to the second electrode sheet 121, and if the polarity of the second electrode sheet 121 is positive, then the pole post 130 is positive and the housing 110 forms the corresponding negative. In another embodiment, if the polarity of the second electrode sheet 121 is negative, then the pole post 130 is negative and the housing 110 forms the corresponding positive. In this embodiment, a mounting hole for the pole post 130 is provided on the second end wall 111. The pole post 130 is sealed and insulated and mounted within the mounting hole for the pole post 130, and the pole post 130 is indirectly electrically connected to the second tab 125 via the second current collector member 150. One end of the pole post 130, away from the electrode assembly 120, is exposed to the outside of the housing 110 and is positively charged.

[0052] The pole post 130 is made of a conductive metallic material. The material of the pole post 130 may be aluminum. If the material of the pole post 130 is aluminum, the riveting process can be easily carried out. In this embodiment, the material of the pole post 130 is aluminum, and its polarity is positive. Corresponding to the pole post 130, the material of the housing 110 is low carbon steel, and correspondingly forms the negative electrode. The pole post 130 and the housing 110 are electrically insulated. Electrical insulation between the pole post 130 and the second end wall 111 of the housing 110 can be achieved in various ways. For example, insulation may be achieved by placing an insulating washer between the pole post 130 and the second end wall 111, or by forming an insulating coating layer on a part of the pole post 130, or a combination of some of the above methods may be applied.

[0053] In this embodiment, the electrode assembly 120 is electrically connected to the housing 110 via a first current collector 140. Furthermore, in some embodiments, the first current collector 140 includes a housing connection portion 145 located on the outer periphery of the first current collector 140, which is welded to the side wall 112. The specific assembly process of this structure involves first welding the housing connection portion 145 to the side wall 112, and then rolling a groove into the side wall 112. Simultaneously, the housing connection portion 145, welded to the side wall 112, is continuously bent toward the axis of the housing 110, and then the first end wall 114 is positioned on the side of the roll groove away from the first current collector 140 and connected to the side wall 112 to seal the opening 113. The method of attaching the first end wall 114 employs a mechanical sealing method to seal and close the opening 113. In some other embodiments, the first end wall 114 seals and closes the opening 113. The shape of the outer edge of the first end wall 114 corresponds to the shape of the opening 113, and the outer edge of the first end wall 114 is welded to the side wall 112 to seal the opening 113, and the first current collector member 140 is welded to the first end wall 114. In this embodiment, the first tab 124 is a negative electrode tab, and the housing 110 is negatively charged by welding the first current collector member 140 to the side wall 112.

[0054] Furthermore, referring to Figures 1 and 3, in this embodiment, a first fluid injection hole 115 is provided on the first end wall 114, and the first current collector member 140 includes a second fluid injection hole 143. The shape of the second fluid injection hole 143 may be circular, ring-shaped, petal-shaped, rectangular, elliptical, polygonal, or other irregular shape. The position of the second fluid injection hole 143 on the first current collector member 140 is not limited and may be a rotationally symmetrical shape with the center of the first current collector member 140 as the center of symmetry, or it may be installed irregularly, but the present invention is not limited thereto. In this embodiment, the second fluid injection hole 143 is a circular central hole that penetrates the thickness direction of the first current collector member 140. In some other embodiments, the first fluid injection hole 115 is provided on the second end wall 111, and the second current collector member 150 includes a second fluid injection hole 143. It should be noted that the following embodiments will all be explained using the first current collector member 140 as an example. However, the following technical solutions can also be applied to the second current collector member 150, and similar technical effects can be obtained, so the explanation will be omitted here.

[0055] Referring to Figures 1 and 3-6, the electrolyte is well absorbed directly by the separator 122 of the third annular region 1243 during the process of inflow. Furthermore, the projection of the second injection hole 143 is projected along the axial direction of the electrode assembly 120 to the end face of the winding structure 126, so that the projection of the second injection hole 143 covers the third annular region 1243, that is, the third annular region 1243 is exposed within the second injection hole 143. This prevents the third annular region 1243 from being shielded by either the first tab 124 or the first current collector 140. Therefore, when the electrolyte is injected from the first injection hole 115, the electrolyte flows directly into the third annular region 1243 exposed within the second injection hole 143. During the inflow process, the electrolyte is directly absorbed by the separator 122 of the third annular region 1243 and penetrates radially, allowing it to permeate the electrode assembly 120. This configuration improves the immersion efficiency of the electrode assembly 120, and simultaneously, by positioning the third annular region 1243 to surround the winding axis of the winding structure 126, the uniformity of electrolyte immersion along the radial direction of the electrode assembly 120 can be improved, thereby improving the performance and lifespan of the battery.

[0056] Furthermore, the first current collector 140 and the first tab 124 are welded together. Since the first tab 124 is not located on the third annular region 1243, exposing the third annular region 1243 into the second injection hole 143 effectively prevents accidental welding into the third annular region 1243 when welding the first current collector 140 and the first tab 124, thereby reducing the risk of burnout of the separator 122.

[0057] Furthermore, in one embodiment of the secondary battery 100 of the present invention, the projection of the second electrolyte injection hole 143 covers the first annular region 1241. The first annular region 1241 is formed by winding a first cut segment 12331. After cutting, the first annular region 1241 is partially covered by the first tab 124, but compared to the uncut segment 12332, the area covered by the first tab 124 is still convenient for electrolyte flow, and the electrolyte can flow in through the gap between the first tab 124 and the first annular region 1241. In addition, the electrolyte is directly absorbed by the separator 122 of the first annular region 1241 during the flow process and penetrates radially, allowing it to infiltrate the electrode assembly 120. This arrangement allows the entire first annular region 1241 to be exposed into the second electrolyte injection hole 143, thereby further improving the infiltration efficiency of the electrode assembly 120. At the same time, the portion of the first annular region 1241 covered by the first tab 124 has fewer layers of the first tab 124 and is not suitable for welding to the first current collector 140. By exposing the entire first annular region 1241 into the second liquid injection hole 143, it is possible to effectively prevent accidental welding to the region with fewer layers of the first tab 124 when welding the first current collector 140 and the first tab 124, thereby reducing the risk of the first tab 124 melting off and the separator 122 burning out.

[0058] Referring to Figures 5 and 6, in one embodiment of the secondary battery 100 of the present invention, the inner radius of the second annular region 1242 is R1, and the winding structure 126 includes a winding hole 127 located at the center, the radius of which is R2. However, R1-R2 ≥ 1 mm, and may be, for example, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, etc. The inner circle of the second annular region 1242 is the inner circle of the region covered by the first tab 124. By limiting R1-R2 ≥ 1 mm, it is possible to have an annular region on the outer circumference of the winding hole 127 that is not shielded by the first tab 124 and has a width of at least 1 mm, and the aforementioned annular region is, i.e., the third annular region 1243. This configuration ensures that the width of the third annular region is not less than 1 mm, thereby further improving the penetration efficiency of the electrode assembly, and further improving the performance and lifespan of the battery.

[0059] Referring to Figures 3, 5, and 6, in one embodiment of the secondary battery 100 of the present invention, when projected onto the end face of the winding structure 126 along the axial direction of the electrode assembly 120, the projected area of ​​the first current collector 140 is S1, and the end face area of ​​the winding structure 126 is S2. However, 0.9S2 ≥ S1 ≥ 0.4S2, which may be, for example, 0.9S2, 0.8S2, 0.6S2, or 0.4S2. Setting S1 ≥ 0.4S2 ensures that the area for welding the first current collector 140 to the first tab 124 is sufficiently large, thereby improving the hardness and reliability of the weld between the first current collector 140 and the electrode assembly 120, and reducing the internal resistance of the battery. Setting S1 ≤ 0.9S2 ensures that the area of ​​the electrode assembly 120 that is not shielded by the first current collector 140 and is exposed to the outside is 0.1S2 or more. This installation is advantageous on the one hand for allowing the electrolyte to penetrate smoothly into the electrode assembly 120 through the unshielded areas, and on the other hand for allowing gas inside the electrode assembly 120 to be discharged from the unshielded areas, thereby improving the safety performance and overall performance of the battery.

[0060] Referring to Figures 3 and 5, in one embodiment of the secondary battery 100 of the present invention, the first current collector 140 includes a plurality of tab connections 141 arranged circumferentially, where the tab connections 141 are regions to which the first current collector 140 and the first tab 124 are welded together. The number of tab connections 141 may be two, three, four, or more, but the present invention is not limited thereto. By providing a transition connection 142 between each pair of adjacent tab connections 141, and by the transition connection 142 connecting adjacent tab connections 141, the first current collector 140 can have better integration, which is advantageous for assembly and welding.

[0061] Referring to Figures 5 and 6, at least one through-hole 144 is provided on each transition connection 142. Along the radial direction of the first current collector 140, the maximum width of the through-hole 144 is L. Multiple rays are created passing through the center of the first current collector 140, and one ray is selected from the above-mentioned rays that intersects the through-hole 144 and forms the maximum width. The width of the corresponding through-hole 144 is, i.e., the maximum width of the through-hole 144. The radius of the winding structure 126 is R3, where L ≥ 0.5 × (R3 - R2), and may be, for example, 0.5 × (R3 - R2), 0.55 × (R3 - R2), 0.6 × (R3 - R2), or 0.65 × (R3 - R2), etc. There may be one or more through-holes 144 provided on the transition connection 142. For example, in this embodiment, two through holes 144 are provided on each transition connection portion 142, and the aforementioned through holes 144 are, that is, the parts on the first current collector member 140 that do not shield the electrode assembly 120. The maximum width of the relatively large waist-shaped hole is indicated by L1, and the maximum width of the relatively small elliptical hole is indicated by L2, where L is the sum of L1 and L2. R3-R2 corresponds to the annular width of the end face of the winding structure 126, and is further limited to L≧0.5×(R3-R2). That is, the maximum width of one through hole 144 on the same transition connection portion 142 or the maximum sum of the widths of multiple through holes 144 is not less than 0.5 times the annular width of the end face of the winding structure 126. This arrangement allows the electrolyte to permeate into the electrode assembly 120 from the through holes 144, thereby improving the electrolyte permeation efficiency. At the same time, by arranging multiple transition connection sections 142 along the circumferential direction of the first current collector member 140, and spacing adjacent transition connection sections 142 with tab connection sections 141, the through holes 144 can be arranged even more uniformly along the circumferential direction of the first current collector member 140. This arrangement further improves the uniformity of electrolyte infiltration and can also improve the performance and lifespan of the battery.

[0062] Referring to Figures 5 and 6, in one embodiment of the secondary battery 100 of the present invention, the maximum distance from the outer edge of the transition connection portion 142 to the center of the first current collector member 140 is R4. The shape of the outer edge of the transition connection portion 142 is not limited and may be circular, polygonal, petal-shaped, or a shape in which a recess is provided on a circular outer edge. Therefore, R4 is the distance of the furthest part from the outer edge of the transition connection portion 142 to the center of the first current collector member 140. The radius of the winding structure 126 is R3, preferably R3 > R4. That is, the distance of the furthest part from the outer edge of the transition connection portion 142 to the center of the first current collector member 140 is smaller than the radius of the outer edge of the winding structure 126. This arrangement further reduces the shielding of the electrode assembly 120 by the first current collector member 140, thereby further improving the electrolyte penetration efficiency, and further improving the performance and lifespan of the battery. Furthermore, since it is possible to prevent the first current collector 140 from interfering when attaching the electrode assembly 120 to the housing 110, assembly efficiency and assembly quality can also be improved.

[0063] Referring to Figures 5 and 6, in one embodiment of the secondary battery 100 of the present invention, the first uncoated region 1233 further includes a second cut segment 12333 located on the outer circumference of the winding structure 126 and adjacent to the uncut segment 12332. Along the radial direction of the electrode assembly 120, the second cut segment 12333 is wound to form a fourth annular region 1244, the inner peripheral radius of the fourth annular region 1244 being R5, preferably R4 ≤ R5. In this technical solution, the fourth annular region 1244 formed by winding the second cut segment 12333 is not obscured by the first tab 124, and the fourth annular region 1244 is located on the outer circumference of the winding structure 126. At the same time, by limiting R4 ≤ R5, that is, the distance from the outer edge of the transition connection portion 142 to the center of the first current collector member 140 to less than or equal to the inner peripheral radius of the fourth annular region 1244, the portion of the fourth annular region 1244 located radially outside the transition connection portion 142 is also prevented from being shielded by the first current collector member 140. Therefore, when electrolyte is injected from the first injection hole 115, the electrolyte flows directly into the exposed portion of the fourth annular region 1244. In the process of flowing in, the electrolyte is directly absorbed by the separator 122 of the fourth annular region 1244 and penetrates simultaneously in the circumferential and radial directions, allowing the electrode assembly 120 to be permeated. This configuration improves the immersion efficiency of the electrode assembly 120, and simultaneously, by positioning the portion of the fourth annular region 1244 not covered by the first current collector 140 along the circumferential direction of the first current collector 140, the uniformity of electrolyte immersion along the radial direction of the electrode assembly 120 can be improved, thereby improving the performance and lifespan of the battery.

[0064] Referring to Figure 3, considering that the first tab 124 located on the outermost periphery is in a free state and is at risk of breaking and falling, in one embodiment of the secondary battery 100 of the present invention, the first current collector 140 covers at least a portion of the first tab 124 located on the outermost periphery of the winding structure 126 along the axial direction of the first current collector 140. By covering and pressing down at least a portion of the first tab 124 located on the outermost periphery of the winding structure 126 with the first current collector 140, the first tab 124 can be effectively prevented from lifting up, thereby reducing the risk of a short circuit caused by the first tab 124 breaking due to the action of an external force and falling into the housing 110.

[0065] Referring to Figures 5 and 6, in one embodiment of the secondary battery 100 of the present invention, R3-R4 may be further limited to ≥ 1 mm, for example, 1 mm, 2 mm, 3 mm, etc. That is, by limiting the difference between the radius of the winding structure 126 and the shortest distance from the outer edge of the transition connection portion 142 to the center of the first current collector member 140 to 1 mm or more, the transition connection portion 142 can cover and press down on as much of the outermost first tab 124 as possible, and at the same time, it is possible to ensure that the area not shielding the electrode assembly 120 becomes larger, thereby reducing the risk of the first tab 124 breaking due to the action of external force and falling into the housing 110, and also achieving the effect of improving the electrolyte infiltration efficiency.

[0066] Referring to Figures 1 and 5, in one embodiment of the secondary battery 100 of the present invention, when projected onto the end face of the winding structure 126 along the axial direction of the electrode assembly 120, the projection of the first electrolyte hole 115 covers at least a portion of the third annular region 1243 which is covered by the projection of the second electrolyte hole 143. As a result, when the electrolyte enters from the first electrolyte hole 115, it can flow directly into the portion of the third annular region 1243 that is not shielded by the first tab 124 and the first current collector 140. Therefore, the electrolyte can be directly absorbed into the separator 122 of the third annular region 1243 and penetrate radially, allowing it to permeate the electrode assembly 120. This configuration further improves the permeation efficiency of the electrode assembly 120.

[0067] Referring to Figure 7, the present invention further provides a battery pack 10, which includes a secondary battery 100 as described in any one of the above-described items. In one embodiment of the battery pack 10 of the present invention, the battery pack 10 includes a box 101, a box cover 102, and a plurality of secondary batteries 100, which are arranged inside the box 101 and connected to each other in series or in parallel, or in a combination of series and parallel. The box cover 102 covers the box 101 and protects the plurality of secondary batteries 100. It should be noted that, in addition to the secondary batteries 100 of the present invention, the battery pack 10 may also include a thermal management system, a circuit board, and other parts of the battery pack 10. The battery pack 10 may be a battery module, a battery pack, a power storage cabinet, etc., but each will not be described individually here.

[0068] Referring to Figure 8, the present invention further provides an electronic device 1, which includes the battery pack 10 described above. A work unit 11 is electrically connected to the battery pack 10 to receive support from electrical energy. As one example, the electronic device 1 is a vehicle, which may be a fuel-powered vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or a range-extender vehicle, etc., but the present invention is not limited thereto. The work unit 11 is the vehicle body, and the battery pack 10 is installed at the bottom of the vehicle body to provide support from electrical energy for the vehicle to run or for the operation of electrical components inside the vehicle. However, in some other embodiments, the electronic device 1 may further be a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, and a power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. The work unit 11 may be a unit component that can perform a corresponding task by obtaining electrical energy from the battery pack 10, for example, a fan blade rotation unit, a vacuum cleaner dust collection work unit, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys. Power tools include metal cutting power tools, polishing power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact electric drills, concrete vibrators, and electric planers. Embodiments of the present invention are not particularly limited to the electronic device 1 described above.

[0069] The secondary battery of the present invention forms a first annular region by winding a first cut segment on the side of the uncoated region closest to the winding axis, and the first annular region includes a third annular region not covered by a tab. Furthermore, the projection of the second electrolyte injection hole of the current collector member covers at least partially the third annular region, and the portion of the third annular region covered by the projection of the second electrolyte injection hole is the portion exposed into the second electrolyte injection hole. Since this portion of the third annular region is not shielded by either the tab or the current collector member, when electrolyte is injected from the first electrolyte injection hole, the electrolyte is directly absorbed into the separator of the third annular region during the inflow process and penetrates radially, allowing it to permeate the electrode assembly. This improves the permeation efficiency of the electrode assembly. Therefore, the present invention can effectively overcome several practical problems in the prior art, thereby having very high utility and significance.

[0070] It should be explained that, as referred to in this invention, an uncut segment refers to a segment in which the tab has not been cut in the stretching direction away from the area coated with the active material.

[0071] The embodiments described above are illustrative in illustrating the principles and effects of the present invention and are not intended to limit the invention. Those skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the invention. Therefore, all modifications or changes made by those skilled in the art without departing from the spirit and technical idea disclosed herein should still be included within the scope of the claims of the invention. [Industrial applicability]

[0072] The secondary battery of the present invention can improve the immersion efficiency of the electrode assembly and, at the same time, improve the uniformity of electrolyte immersion along the radial direction of the electrode assembly, thereby improving the performance and lifespan of the battery. [Explanation of Symbols]

[0073] 1. Electronic devices 10 battery packs 11 Work Unit 101 Boxes 102 Box Cover 100 Secondary battery 110 cabinets 111 Second End Wall 112 Side wall 113 Aperture 114 First End Wall 115 First injection port 120 Electrode Assembly 121 Second electrode sheet 1211 Positive electrode current collector 1212 2nd application area 1213 2nd uncoated area 122 Separator 123 First electrode sheet 1231 Negative electrode current collector 1232 1st application area 1233 1st uncoated area 12331 First Cut Segment 12332 Uncut segment 12333 Second Cutting Segment 124 Tab 1 1241 First Ring Region 1242 Second Ring Region 1243 Third Ring Region 1244 Fourth Ring Region 125 Second Tab 126-wound structure 127 winding holes 130 Pole Pillar 140 First current collector 141 Tab connection section 142 Transition Connection Section 143 Second injection port 144 Through holes 145 Enclosure connection section 150 Second current collector

Claims

1. A housing including an end wall, on which a first liquid injection hole is installed, An electrode assembly comprising a winding structure housed within the housing and formed by stacking and winding a first electrode sheet, a second electrode sheet, and a separator, wherein the end of the first electrode sheet includes an uncoated region protruding from the separator along the axial direction of the electrode assembly, the uncoated region includes a first cut segment near the winding axis of the winding structure and an uncut segment located radially outward of the first cut segment, the uncut segment of the uncoated region is bent to form a tab, the first cut segment is wound along the radial direction of the electrode assembly to form a first annular region, the region covered by the tab is a second annular region, and the first annular region includes a third annular region not covered by the second annular region, A current collector member is installed between the electrode assembly and the end wall, welded to the tab, and includes a second liquid injection hole. A secondary battery comprising, characterized in that, when projected along the axial direction of the electrode assembly onto the end face of the winding structure, the projection of the second liquid injection hole covers the third annular region.

2. The secondary battery according to claim 1, characterized in that the projection of the second liquid injection hole covers the first annular region.

3. The secondary battery according to claim 1, characterized in that the inner radius of the second annular region is R1, the winding structure includes a winding hole located at the center, and the radius of the winding hole is R2, provided that R1 - R2 ≥ 1 mm.

4. The secondary battery according to claim 3, characterized in that when the projection of the current collector member is made along the axial direction of the electrode assembly to the end face of the winding structure, the projected area of ​​the current collector member is S1, and the end face area of ​​the winding structure is S2, provided that 0.9S2 ≥ S1 ≥ 0.4S2.

5. The secondary battery according to claim 4, characterized in that the current collecting member includes a plurality of tab connection portions arranged along the circumferential direction, one transition connection portion is provided between each pair of adjacent tab connection portions, at least one through hole is provided on each transition connection portion, the maximum width of the through hole along the radial direction of the current collecting member is L, and the radius of the winding structure is R3, where L ≥ 0.5 × (R3 - R2).

6. The secondary battery according to claim 1, characterized in that the current collecting member includes a plurality of tab connection portions arranged along the circumferential direction, one transition connection portion is provided between each pair of adjacent tab connection portions, the maximum distance from the outer edge of the transition connection portion to the center of the current collecting member is R4, and the radius of the winding structure is R3, provided that R3 > R4.

7. The secondary battery according to claim 6, wherein the uncoated region further includes a second cut segment located on the outer circumference of the winding structure and adjacent to the uncut segment, the second cut segment is wound along the radial direction of the electrode assembly to form a fourth annular region, and the inner peripheral radius of the fourth annular region is R5, provided that R4 ≤ R5.

8. The secondary battery according to claim 6, characterized in that the current collecting member covers at least a portion of the tab located on the outermost periphery of the winding structure along the axial direction of the current collecting member.

9. The secondary battery according to claim 8, characterized in that R3 - R4 ≥ 1 mm.

10. The secondary battery according to claim 1, characterized in that when projected onto the end face of the winding structure along the axial direction of the electrode assembly, the projection of the first liquid injection hole covers at least a portion of the third annular region covered by the projection of the second liquid injection hole.

11. The secondary battery according to claim 1, characterized in that the uncut segment of the uncoated region is bent toward the center of the electrode assembly to form the tab.

12. A battery pack characterized by including a secondary battery according to any one of claims 1 to 11.

13. An electronic device characterized by including the battery pack described in claim 12.

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