Single cell and battery pack

Abstract

Disclosed in the embodiments of the present application are a single cell and a battery pack. The single cell comprises: a casing; an electrode assembly arranged in the casing; an end cover arranged at one axial end of the casing and connected to the casing; and a current-collecting member, comprising: a current-collecting body and electrical connection portions connected to the current-collecting body, wherein the current-collecting body is arranged between the electrode assembly and the end cover, and the current-collecting body is electrically connected to the electrode assembly by means of the electrical connection portions. The current-collecting body comprises welding areas, the electrical connection portions are arranged in the welding areas, a plurality of electrical connection portions are provided, and the plurality of electrical connection portions are arranged spaced apart from one another in the radial direction. In the radial direction, the maximum dimension of each electrical connection portion is L1 mm, and the spacing between every two adjacent electrical connection portions is L2 mm, L1 and L2 satisfying: 0.01≤L1 / L2≤2.

Description

Individual cells and battery packs

[0001] This application claims priority to Chinese Utility Model Patent Application No. 202520501846.7, filed on March 20, 2025, entitled "Single Battery and Battery Pack", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and in particular to a single cell battery and a battery pack. Background Technology

[0003] The replacement of traditional gasoline-powered vehicles with new energy vehicles is of great significance in improving the energy and pollution problems faced by the global transportation industry, and it is also an inevitable trend. With the rapid development of the new energy industry, the demand for batteries with larger capacity, greater durability, and longer driving range is extremely urgent. As one of the core performance characteristics of batteries, how to improve battery rate performance has become a pressing issue that needs to be addressed.

[0004] Application content

[0005] Embodiments of this application provide a single-cell battery and a battery pack to improve the rate performance of the single-cell battery.

[0006] In a first aspect of this application, a single-cell battery is provided. The single-cell battery includes: a housing having intersecting axial and radial directions; an electrode assembly disposed within the housing; an end cap disposed at one axial end of the housing and connected to the housing; and a current collector, the current collector including: a current collector body and an electrical connection portion connecting the current collector body, the current collector body being disposed between the electrode assembly and the end cap, and the current collector body being electrically connected to the electrode assembly through the electrical connection portion, wherein the current collector body includes a welding area, the electrical connection portion is disposed in the welding area, and multiple electrical connection portions are provided, the multiple electrical connection portions being radially spaced apart, and in the radial direction, the maximum dimension of each electrical connection portion is L1 mm, the distance between two adjacent electrical connection portions is L2 mm, and L1 and L2 satisfy: 0.01≤L1 / L2≤2.

[0007] In addition to one or more of the features disclosed above, or alternatively, the maximum radial dimension L1 mm of each electrical connection also satisfies: 0.1 ≤ L1 ≤ 1.

[0008] In addition to one or more of the features disclosed above, or alternatively, the radial spacing L2 mm between two adjacent electrical connections also satisfies: 0.5 ≤ L2 ≤ 10.

[0009] In addition to one or more of the features disclosed above, or alternatively, the maximum radial dimension L1 mm of each electrical connection also satisfies: 0.1≤L1≤1, and the radial spacing L2 mm between two adjacent electrical connections also satisfies: 0.5≤L2≤10.

[0010] In addition to one or more of the features disclosed above, or alternatively, the housing also has a reference plane perpendicular to the axial direction, the orthographic projection of the welded area onto the reference plane is fan-shaped, and the two radii of the welded area extend radially respectively.

[0011] In addition to one or more of the features disclosed above, or alternatively, the single cell also has a circumferential orientation around the axial direction, with multiple electrical connections in the welding area extending circumferentially and having a consistent curvature.

[0012] In addition to one or more of the features disclosed above, or as an alternative, the central angle of the sector projection of the welded area onto the reference plane is α, where α satisfies: 9°≤α.

[0013] In addition to one or more of the features disclosed above, or alternatively, the single cell also has multiple welding areas arranged around the axial direction, the multiple welding areas are spaced apart along the circumference, and the radii of the multiple welding areas intersect at a common center, and the multiple welding areas are symmetrical about the common center.

[0014] In addition to one or more of the features disclosed above, or alternatively, the sum of the central angles of the sector projections of the multiple welded areas onto the reference plane P is α. m α m Satisfy: 18°≤α m ≤360°.

[0015] In addition to one or more of the features disclosed above, or alternatively, the central angles of the sector projections of multiple welded areas on the reference plane are the same.

[0016] In addition to one or more of the features disclosed above, or alternatively, the central angles of the sector projections of the multiple welded areas on the reference plane are different.

[0017] In addition to one or more of the features disclosed above, or alternatively, the housing also has a circumferential direction around the axial direction and a reference plane perpendicular to the axial direction. Each electrical connection extends circumferentially, and the orthographic projection of each electrical connection on the reference plane is an arc shape arranged around a common center, and each welding area is provided with a plurality of electrical connections spaced apart in the radial direction.

[0018] In addition to one or more of the features disclosed above, or alternatively, the maximum circumferential dimension of the electrical connection increases radially, in a direction away from the common center.

[0019] In addition to one or more of the features disclosed above, or as an alternative, the electrode assembly is welded to the current collector to form an electrical connection.

[0020] In a second aspect of this application, a battery pack is further disclosed. In addition to one or more features disclosed above, or alternatively, the battery pack includes a housing; and individual battery cells according to the first aspect of this application, the individual battery cells being disposed within the housing.

[0021] In the battery cell provided in this application embodiment, by limiting the ratio of the maximum size L1 mm of each electrical connection in the radial X direction to the distance L2 mm between two adjacent electrical connections in the radial X direction to be within the range of 0.01 to 2, the structural dimensions of the electrical connections on the current collector are reasonably designed, thereby optimizing the electron conduction path in the battery cell, reducing the impedance of the battery cell, improving the overall overcurrent performance of the battery cell, and thus improving the rate performance and cycle performance of the battery cell. Attached Figure Description

[0022] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0023] Figure 1 schematically shows an exploded view of a single cell provided according to some embodiments of this application;

[0024] Figure 2 schematically shows a top view of a current collection component provided according to some embodiments of this application;

[0025] Figure 3 schematically shows a top view of a current collection component provided according to other embodiments of this application.

[0026] Explanation of reference numerals in the attached drawings: 100, single cell; 110, casing; 120, electrode assembly; 130, end cap; 140, current collector; 141, current collector body; 1411, welding area; 142, electrical connection. Detailed Implementation

[0027] To make the objectives, technical solutions, and beneficial effects of this application clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates this application. It should be understood that the specific embodiments described in this specification are merely for explaining this application and are not intended to limit it.

[0028] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0029] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0030] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] Existing cylindrical secondary batteries feature a multi-tab or all-tab design, with the tabs and terminals electrically connected via current collectors. Currently, the welding trajectory between the current collector and the tabs in existing cylindrical secondary batteries is linear and distributed radially along the battery. Because the lengths of the electrode sheets at different levels within the inner and outer rings of the electrode assembly differ, the conduction current of the electrode sheets gradually increases from the inside to the outside, and the current-carrying requirements for the tab welding also gradually increase from the inside to the outside. However, this linear welding trajectory distributed radially along the battery not only fails to meet the differentiated current-carrying capacity requirements of the electrode sheets at different levels within the inner and outer rings, but also easily leads to performance failure or degradation of the battery under high-rate charge and discharge conditions, thus affecting battery performance.

[0032] To address the aforementioned problems, in the embodiments of this application, referring to Figures 1 to 3, a single-cell battery 100 is provided. Specifically, the single-cell battery 100 includes: a housing 110, an electrode assembly 120, an end cap 130, and a current collector 140.

[0033] The housing 110 has an axial direction Z, a radial direction X intersecting the axial direction Z, a circumferential direction R around the axial direction Z, and a reference plane perpendicular to the axial direction Z. For example, the housing 110 has an axial direction Z, a radial direction X perpendicular to the axial direction Z, a circumferential direction R around the axial direction Z, and a reference plane P perpendicular to the axial direction Z.

[0034] Electrode assembly 120 is disposed within housing 110. End cap 130 is disposed at one end of housing 110 in the Z-axis direction and is connected to housing 110. Current collector 140 includes current collector body 141 and electrical connection portion 142 connecting current collector body 141. Current collector body 141 is disposed between electrode assembly 120 and end cap 130, and current collector body 141 is electrically connected to electrode assembly 120 through electrical connection portion 142.

[0035] In some embodiments, the single-cell battery 100 can be a rechargeable battery. A rechargeable battery is a single-cell battery that can be recharged to activate the active materials and continue to be used after the single-cell battery has been discharged. For example, the single-cell battery 100 can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, or nickel-cadmium battery, but is not limited thereto.

[0036] In some embodiments, the single cell 100 may be a prismatic cell, a pouch cell, or a cell of other shapes. For example, in the embodiment shown in FIG1, the single cell 100 is a cylindrical cell.

[0037] In some embodiments, the housing 110 described above may be made of a material with good mechanical strength, such as metal, but is not limited thereto. For example, the housing 110 described above is made of aluminum profile, but is not limited thereto.

[0038] In some embodiments, the end cap 130 may be integrally formed with the housing 110, that is, the end cap 130 and the housing 110 may be a single piece. In some embodiments, the end cap 130 and the housing 110 may be separate pieces, and the end cap 130 and the housing 110 may be fixedly connected, for example, the end cap 130 may be fixedly connected to one end of the housing 110 in the axial Z direction by welding or other processes. This application does not impose specific limitations on this, and the specific connection relationship between the end cap 130 and the housing 110 may be specifically set according to the actual situation. For example, in the embodiment shown in FIG1, the end cap 130 and the housing 110 are separately disposed, and the end cap 130 and the housing 110 are fixedly welded together.

[0039] In some embodiments, the current collector 140 can be a positive current collector or a negative current collector. This application does not impose specific limitations on this; it can be configured according to actual circumstances.

[0040] The current collector 140 can be made of various materials. For example, the current collector 140 can be made of copper, iron, aluminum, steel or aluminum alloy, but is not limited to these.

[0041] In some embodiments, the electrode assembly 120 is welded to the current collector 140 to form an electrical connection 142. Specifically, the tabs in the electrode assembly 120 are welded to the current collector 140 to form the electrical connection 142.

[0042] In some embodiments, the single-cell battery 100 further includes an electrolyte, terminals, and other functional components. The electrolyte can be a conventional electrolyte or a special electrolyte with added additives, and is used to wet the electrode assembly 120. The electrode assembly 120 is the component in the single-cell battery 100 where electrochemical reactions occur, and there can be one or more electrode assemblies. The electrode assembly 120 is mainly formed by winding or stacking a positive electrode, a separator, and a negative electrode. The portions of the positive and negative electrode with active material constitute the main body of the electrode assembly 120, and the portions of the positive and negative electrode without active material constitute the tabs. During the charging and discharging process of the single-cell battery 100, the positive and negative active materials react with the electrolyte, and the tabs are electrically connected to the terminals through the current collector 140 to form a current loop, enabling the single-cell battery 100 to function normally.

[0043] Specifically, the current collector body 141 includes a welding area 1411, and an electrical connection portion 142 is disposed in the welding area 1411. Multiple electrical connection portions 142 are disposed at intervals in the radial direction X, so that the multiple electrical connection portions 142 are respectively electrically connected to the tabs of different levels in the electrode assembly 120, thereby optimizing the electronic conduction path in the single cell 100, reducing the impedance of the single cell 100, and improving the overall overcurrent performance of the single cell 100.

[0044] Specifically, in the radial direction X, the maximum dimension of each electrical connection 142 is L1 mm, and the distance between two adjacent electrical connection parts 142 is L2 mm. L1 and L2 satisfy: 0.01 ≤ L1 / L2 ≤ 2. That is, the ratio of the maximum dimension L1 mm of each electrical connection part 142 in the radial direction X to the distance L2 mm between two adjacent electrical connection parts 142 in the radial direction X can be controlled within the range of 0.01 to 2. For example, L1 / L2 can be one of 0.01, 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, or 2, or any combination of two of them. The specific values ​​of L1 / L2 given above are only illustrative examples, and any value within the range of 0.01 to 2 is within the protection scope of this application.

[0045] In the radial direction X, the maximum dimension L1 mm of each electrical connection 142 is obtained, for example, by disassembling the actual single battery cell 100 and measuring the dimension in the radial direction X at different positions of each electrical connection 142 on the current collector 140 multiple times using a measuring tool, calculating the average value of these dimensions, and taking this average value as the dimension L1 mm. For example, the maximum dimension L1 mm of each electrical connection 142 in the radial direction X is obtained, for example, by measuring the dimensions in the radial direction X at both ends of the electrical connection 142 and the dimensions in the radial direction X at the middle region of the electrical connection 142 using a measuring tool, calculating the average value of these dimensions, and taking this average value as the maximum dimension L1 mm of the electrical connection 142 in the radial direction X. The measuring tool can be any one of a ruler, vernier caliper, or other dimensional measuring instruments, but is not limited thereto.

[0046] In the radial direction X, the distance L2 mm between two adjacent electrical connection portions 142 is obtained, for example, by disassembling the actual single cell 100 and measuring the distance in the radial direction X at different positions of two adjacent electrical connection portions 142 on the current collector 140 multiple times using a measuring tool, calculating the average value of these distances, and using this average value as the distance L2 mm. For example, the distance L2 mm between two adjacent electrical connection portions 142 in the radial direction X is obtained, for example, by measuring the distance in the radial direction X between the two ends of the two adjacent electrical connection portions 142 and the distance in the radial direction X between the middle regions of the two adjacent electrical connection portions 142 using a measuring tool, calculating the average value of these distances, and using this average value as the distance L2 mm between the two adjacent electrical connection portions 142 in the radial direction X. The measuring tool can be any one of a ruler, vernier caliper, or other dimensional measuring instruments, but is not limited thereto.

[0047] In the battery cell provided in this application embodiment, by limiting the ratio of the maximum size L1 mm of each electrical connection portion 142 in the radial X direction to the distance L2 mm between two adjacent electrical connection portions 142 in the radial X direction to be within the range of 0.01 to 2, the structural dimensions of the electrical connection portions 142 on the current collector 140 are reasonably designed, thereby optimizing the electronic conduction path in the battery cell 100, reducing the impedance of the battery cell 100, improving the overall overcurrent performance of the battery cell 100, and thus improving the rate performance and cycle performance of the battery cell 100.

[0048] In some embodiments, the maximum dimension L1 mm of each electrical connection portion 142 in the radial X direction also satisfies: 0.1 ≤ L1 ≤ 1, that is, the maximum dimension L1 mm of each electrical connection portion 142 in the radial X direction can be controlled within the range of 0.1 mm to 1 mm. For example, L1 mm can be one or a combination of any two of the following: 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1 mm. The specific values ​​of L1 mm given above are merely illustrative; any value within the range of 0.1 mm to 1 mm is within the scope of protection of this application.

[0049] In the battery cell provided in this application embodiment, by limiting the maximum size L1 of each electrical connection portion 142 in the radial X direction to within the range of 0.1mm to 1mm, the structural dimensions of the electrical connection portion 142 on the current collector 140 are designed more reasonably, further optimizing the electronic conduction path in the battery cell 100, reducing the impedance of the battery cell 100, improving the overall overcurrent performance of the battery cell 100, and thus improving the rate performance and cycle performance of the battery cell 100.

[0050] In some embodiments, the maximum dimension L1 mm of each electrical connection 142 in the radial X direction is the same.

[0051] In some embodiments, the radial distance L2 mm between two adjacent electrical connection portions 142 further satisfies: 0.5 ≤ L2 ≤ 10, that is, the radial distance L2 between two adjacent electrical connection portions 142 can be controlled within the range of 0.5 mm to 10 mm. For example, L2 mm can be one or any combination of 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, or 10 mm. The specific values ​​of L2 mm given above are merely illustrative; any value within the range of 0.5 mm to 10 mm is within the scope of protection of this application.

[0052] In the battery cell 100 provided in this application embodiment, by limiting the distance L2 between two adjacent electrical connection portions 142 in the radial X direction to within the range of 0.5mm to 10mm, the structural dimensions of the electrical connection portions 142 on the current collector 140 are designed more reasonably, further optimizing the electronic conduction path in the battery cell 100, reducing the impedance of the battery cell 100, improving the overall overcurrent performance of the battery cell 100, and thus improving the rate performance and cycle performance of the battery cell 100.

[0053] In some embodiments, each electrical connection 142 extends along the circumferential direction R, and the orthographic projection of each electrical connection 142 on the reference plane P is an arc shape arranged around a common center Q, and each welding area 1411 is provided with a plurality of electrical connections 142 spaced apart in the radial direction X.

[0054] Understandably, since the electrode assembly 120 is formed by winding electrode sheets, each turn of the electrode sheet is arc-shaped, and the tabs on each turn of the electrode sheet are also arranged in an arc shape. In the battery cell 100 provided in this application embodiment, by limiting the orthographic projection of each electrical connection portion 142 on the reference plane P to be arc-shaped, it is ensured that the shape of each electrical connection portion 142 matches the tab, further optimizing the electronic conduction path in the battery cell 100 and improving the overall overcurrent performance of the battery cell 100.

[0055] In some embodiments, the maximum dimension of the electrical connection portion 142 in the circumferential direction R increases in the radial direction X, in the direction away from the common center Q. That is, in any two adjacent electrical connection portions 142 in the radial direction X, the maximum dimension of the electrical connection portion 142 away from the common center Q in the circumferential direction R is larger than the maximum dimension of the electrical connection portion 142 closer to the common center Q in the circumferential direction R.

[0056] Understandably, since the electrode assembly 120 is formed by winding electrode sheets, the lengths of the electrode sheets at different levels are different, resulting in different currents conducted by the electrode sheets at different levels. In the battery cell provided in this application embodiment, by limiting the maximum size variation of multiple electrical connection portions 142 arranged sequentially along the radial direction X in the circumferential direction R, it is ensured that the different electrical connection portions 142 are fully matched with the tabs of the electrode sheets at different levels, further optimizing the electronic conduction path in the battery cell 100, meeting the overcurrent requirements of the electrode sheets at different levels, and improving the overall overcurrent performance of the battery cell 100.

[0057] In some embodiments, the current collector body 141 includes a welding area 1411, an electrical connection portion 142 is disposed on the welding area 1411, and the orthographic projection of the welding area 1411 on the reference plane P is fan-shaped, and the two radii of the welding area 1411 extend radially X.

[0058] It is understood that in the battery cell 100 provided in this application embodiment, by defining the welding area 1411 as a fan shape, the curvature of the multiple electrical connection portions 142 located in the welding area 1411 is consistent, ensuring that each electrical connection portion 142 meets the overcurrent requirements of different levels of the electrode assembly 120 with the smallest area, thereby improving the performance of the battery cell 100.

[0059] In some embodiments, the central angle of the sector projection of the welding area 1411 onto the reference plane P is α, where α satisfies: 9° ≤ α. That is, the central angle α of the sector projection of the welding area 1411 onto the reference plane P is not less than 9°. For example, the central angle α can be one of 9°, 18°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, 330°, or 360°, but is not limited thereto. The specific values ​​of the central angle α described above are merely illustrative; any value within the range of not less than 9° is within the scope of protection of this application.

[0060] In some embodiments, the central angle α of the sector projection of the welding area 1411 on the reference plane P can be obtained, for example, by disassembling the actual single cell 100 and measuring the central angle of the welding area 1411 on the current collector 140 multiple times using a measuring tool, calculating the average value of these central angles, and using this average value as the central angle α. For example, the central angle α of the sector projection of the welding area 1411 on the reference plane P can be obtained, for example, by connecting the two ends of any two electrical connection portions 142 located on the same side within the welding area 1411 to generate auxiliary lines, generating two auxiliary lines on both sides of the two electrical connection portions 142, measuring the included angle between the two auxiliary lines multiple times using a measuring tool, and calculating the average value of these included angles, which can be used as the central angle α of the sector projection of the welding area 1411 on the reference plane P. The measuring tool can be a protractor, but is not limited to this.

[0061] In the battery cell 100 provided in this application embodiment, by limiting the central angle α of the sector projection of the welding area 1411 on the reference plane P to not less than 9°, it is ensured that the welding area 1411 has sufficient welding area, thereby ensuring that the electrical connection part of the welding area 1411 has sufficient connection area to be electrically connected to the electrode assembly 120. This optimizes the electronic conduction path in the battery cell 100, reduces the impedance of the battery cell 100, improves the overall overcurrent performance of the battery cell 100, and ultimately improves the rate performance of the battery cell 100.

[0062] In some embodiments, multiple welding areas 1411 are provided. Exemplarily, two welding areas 1411 may be provided, or four welding areas 1411 may be provided, but not limited thereto. The multiple welding areas 1411 are arranged at intervals along the circumferential direction R, and the radii of the multiple welding areas 1411 intersect at a common center Q. The multiple welding areas 1411 may be centrally symmetrical about the common center Q.

[0063] In some embodiments, the central angles of the sector projections of the multiple welding areas 1411 on the reference plane P may be the same or different. This application does not make specific limitations. The central angles of the sector projections of each welding area 1411 on the reference plane P can be specifically selected according to the actual situation.

[0064] In some embodiments, a non-welded area is formed between two adjacent welded areas 1411. It is understood that in the battery cell 100 provided in this application embodiment, by providing multiple welded areas 1411 and electrically connecting them to the tabs of the electrode assembly 120 via electrical connection portions 142 within the multiple welded areas 1411, multiple current conduction paths are formed between the current collector 140 and the tabs of the electrode assembly 120. This further optimizes the electronic conduction path in the battery cell 100, reduces the impedance of the battery cell 100, improves the overall overcurrent performance of the battery cell 100, and thus improves the rate performance of the battery cell 100.

[0065] In some embodiments, the sum of the central angles of the sector projections of the plurality of welding areas 1411 onto the reference plane P is α. m α m Satisfy: 18°≤α m ≤360°. That is, the sum of the central angles α of the sector projections of multiple welding areas 1411 onto the reference plane P. m It can be controlled within the range of 18° to 360°. For example, α... m It can be a range of one or any two of the following: 18°, 20°, 40°, 60°, 80°, 100°, 120°, 140°, 160°, 180°, 200°, 220°, 240°, 260°, 280°, 300°, 320°, 340°, or 360°. α m The specific values ​​mentioned above are merely illustrative examples, and any value within the range of 18° to 360° is within the scope of protection of this application.

[0066] In some embodiments, the sum of the central angles α of the sector projections of the plurality of welding regions 1411 onto the reference plane P is... m For example, it can be obtained by disassembling the actual single cell 100, measuring the central angles of multiple welding areas 1411 on the current collector 140 using measuring tools, and summing them up.

[0067] In the battery cell 100 provided in this application embodiment, the sum of the central angles α of the sector projections of the plurality of welding regions 1411 onto the reference plane P is used. m By limiting the range to 18° to 360°, the welding area 1411 is further guaranteed to have sufficient welding area, which in turn guarantees that the electrical connection part of the welding area 1411 has sufficient connection area to be electrically connected to the electrode assembly 120. This optimizes the electronic conduction path in the single cell 100, reduces the impedance of the single cell 100, improves the overall overcurrent performance of the single cell 100, and thus improves the rate performance of the single cell 100.

[0068] On the other hand, embodiments of this application also provide a battery pack, the battery pack including: a housing; and a single battery cell 100 as described in any of the above embodiments, the single battery cell 100 being disposed within the housing.

[0069] In some embodiments, the battery pack can be a three-tiered battery pack with individual battery cells 100, battery modules, and a battery pack. That is, the individual battery cells 100 are first assembled into battery modules, and then the battery modules are placed inside a housing to form the battery pack. In some embodiments, the battery pack can also be a two-tiered battery pack with individual battery cells 100 and a battery pack. That is, the individual battery cells 100 are directly housed inside a housing to form the battery pack. This application does not impose specific limitations on this; the number of tiers in the battery pack can be set according to actual circumstances, as long as it does not affect the effectiveness of this application.

[0070] On the other hand, embodiments of this application also provide an electrical device, which includes a battery pack as described above, and the battery pack serves as the power supply for the electrical device.

[0071] In some embodiments, the electrical device may be, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0072] To better understand the technical solutions of the embodiments of this application, the following explanation uses a lithium-ion battery as an example.

[0073] Example 1

[0074] This embodiment provides a method for preparing a lithium-ion battery, the specific process of which is as follows:

[0075] 1. Preparation of positive electrode sheet

[0076] The positive electrode active material is lithium iron phosphate, the conductive agent is conductive carbon black (SP), and the binder is polyvinylidene fluoride (PVDF). The positive electrode active material, conductive agent, and binder are mixed at a mass ratio of 96:2:2. Then, N-methylpyrrolidone (NMP) is added as a solvent for further mixing, and the mixture is stirred under vacuum until homogeneous, yielding a positive electrode slurry. The positive electrode slurry is uniformly coated on both sides of the positive electrode current collector aluminum foil, which is then transferred to a 120°C oven for drying. Finally, the positive electrode current collector aluminum foil is rolled, slit, and cut into sheets to obtain the positive electrode sheet.

[0077] 2. Preparation of negative electrode sheet

[0078] The negative electrode active material is graphite, the conductive agent is conductive carbon black (SP), the thickener is sodium carboxymethyl cellulose (CMC), and the binder is styrene-butadiene rubber (SBR). The negative electrode active material, conductive agent, thickener, and binder are mixed at a mass ratio of 96.2:1.2:1.2:1.4, then deionized water is added as a solvent for further mixing. The mixture is stirred under vacuum until homogeneous, yielding the negative electrode slurry. The negative electrode slurry is then uniformly coated on both sides of the negative electrode current collector copper foil, which is subsequently transferred to a 110°C oven for drying. Finally, the negative electrode current collector copper foil is rolled, slit, and cut into sheets to obtain the negative electrode sheet.

[0079] 3. Preparation of electrolyte

[0080] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a mass ratio of 3:4:3 to obtain an organic solvent. 1 mol / L of LiPF6 was added and mixed thoroughly. Then, vinylene carbonate, ethylene sulfate, and lithium difluorophosphate were added to prepare an electrolyte.

[0081] 4. Preparation of the diaphragm

[0082] PP film is used as the separator.

[0083] 5. Preparation of lithium-ion batteries

[0084] After drying, the negative and positive electrode sheets prepared using the above steps are wound together with the separator using a winding machine to form an electrode roll. The positive or negative electrode tabs are then welded onto the current collector 140, and the welded electrode assembly with end caps is placed into an aluminum shell for encapsulation. After filling with electrolyte and undergoing formation and volume determination, a lithium-ion battery is obtained.

[0085] The lithium-ion battery prepared in Example 1 corresponds to Example 1 in Table 1 below. In the lithium-ion battery provided in Example 1, the current collector 140 has two welding areas, each welding area 1411 has seven electrical connections 142, the maximum radial dimension L1 mm of each electrical connection 142 is 1 mm, the radial spacing L2 mm between two adjacent electrical connections 142 is 2 mm, the ratio L1 / L2 of the maximum radial dimension L1 mm of each electrical connection 142 and the radial spacing L2 mm between two adjacent electrical connections 142 is 0.5, the central angle α of the sector projection of the welding area 1411 on the reference plane P is 90°, and the sum of the central angles α of the sector projections of multiple welding areas 1411 on the reference plane P is... m It is 180°.

[0086] The lithium-ion batteries corresponding to Examples 2 to 16 in Table 1 below were all prepared according to the method in Example 1. The difference between Examples 2 to 16 and Example 1 is the change in the values ​​of L1, L2 and L1 / L2.

[0087] The lithium-ion batteries corresponding to Examples 17 to 25 in Table 1 below were all prepared according to the method in Example 1. The differences between Examples 17 to 25 and Example 1 are: the number of welding areas, α, and α. m Changes in numerical values.

[0088] Comparative Example 1

[0089] Comparative Example 1 corresponds to Comparative Example 1 in Table 1 below. The lithium-ion battery corresponding to Comparative Example 1 was prepared according to the method of Example 1, the difference being:

[0090] In Comparative Example 1, the maximum radial dimension L1 mm of each electrical connection 142 is 0.09 mm. The radial distance L2 mm between two adjacent electrical connection 142 is 11 mm. The ratio L1 / L2 of the maximum radial dimension L1 mm of each electrical connection 142 and the radial distance L2 mm between two adjacent electrical connection 142 is 0.008.

[0091] Comparative Example 2

[0092] Comparative Example 2 corresponds to Comparative Example 2 in Table 1 below. The lithium-ion battery corresponding to Comparative Example 2 was prepared according to the method of Example 1, the difference being:

[0093] In Comparative Example 2, the maximum radial dimension L1 mm of each electrical connection 142 is 1.2 mm. The radial spacing L2 mm between two adjacent electrical connections 142 is 0.4 mm. The ratio L1 / L2 of the maximum radial dimension L1 mm of each electrical connection 142 and the radial spacing L2 mm between two adjacent electrical connections 142 is 3.

[0094] Comparative Example 3

[0095] Comparative Example 3 corresponds to Comparative Example 3 in Table 1 below. The lithium-ion battery corresponding to Comparative Example 3 was prepared according to the method of Example 1, the difference being:

[0096] In Comparative Example 3, the central angle α of the sector projection of each welded region 1411 onto the reference plane P is 5°. The sum of the central angles α of the sector projections of multiple welded regions 1411 onto the reference plane P is... m It is 10°.

[0097] Comparative Example 4

[0098] Comparative Example 4 corresponds to Comparative Example 4 in Table 1 below. The lithium-ion battery corresponding to Comparative Example 4 was prepared according to the method of Example 1, the difference being:

[0099] In Comparative Example 4, the current collector 140 has four welded areas. The central angle α of the sector projection of each welded area 1411 onto the reference plane P is 4°. The sum of the central angles α of the sector projections of the multiple welded areas 1411 onto the reference plane P is... m It is 16°.

[0100] Comparative Example 5

[0101] Comparative Example 5 corresponds to Comparative Example 5 in Table 1 below. The lithium-ion battery corresponding to Comparative Example 5 was prepared according to the method of Example 1, the difference being:

[0102] In Comparative Example 5, the maximum radial dimension L1 mm of each electrical connection 142 is 0.09 mm. The radial spacing L2 mm between two adjacent electrical connections 142 is 11 mm. The ratio L1 / L2 of the maximum radial dimension L1 mm of each electrical connection 142 and the radial spacing L2 mm between two adjacent electrical connections 142 is 0.008. The central angle α of the sector projection of each welding area 1411 on the reference plane P is 5°. The sum of the central angles α of the sector projections of multiple welding areas 1411 on the reference plane P is... m It is 10°.

[0103] Comparative Example 6

[0104] Comparative Example 6 corresponds to Comparative Example 6 in Table 1 below. The lithium-ion battery corresponding to Comparative Example 6 was prepared according to the method of Example 1, the difference being:

[0105] In Comparative Example 6, the maximum radial dimension L1 mm of each electrical connection 142 is 1.2 mm. The radial spacing L2 mm between two adjacent electrical connections 142 is 0.4 mm. The ratio L1 / L2 of the maximum radial dimension L1 mm of each electrical connection 142 and the radial spacing L2 mm between two adjacent electrical connections 142 is 3. The central angle α of the sector projection of each welding area 1411 on the reference plane P is 5°. The sum of the central angles α of the sector projections of multiple welding areas 1411 on the reference plane P is... m It is 10°.

[0106] Comparative Example 7

[0107] Comparative Example 7 corresponds to Comparative Example 7 in Table 1 below. The lithium-ion battery corresponding to Comparative Example 7 was prepared according to the method of Example 1, the difference being:

[0108] In Comparative Example 7, the current collector 140 has four welded areas. The maximum radial dimension L1 mm of each electrical connection 142 is 0.09 mm. The radial spacing L2 mm between two adjacent electrical connections 142 is 11 mm. The ratio L1 / L2 of the maximum radial dimension L1 mm of each electrical connection 142 and the radial spacing L2 mm between two adjacent electrical connections 142 is 0.008. The central angle α of the sector projection of each welded area 1411 on the reference plane P is 4°. The sum of the central angles α of the sector projections of multiple welded areas 1411 on the reference plane P is... m It is 16°.

[0109] Comparative Example 8

[0110] Comparative Example 8 corresponds to Comparative Example 8 in Table 1 below. The lithium-ion battery corresponding to Comparative Example 8 was prepared according to the method of Example 1, the difference being:

[0111] In Comparative Example 8, the current collector 140 has four welded areas. The maximum radial dimension L1 mm of each electrical connection 142 is 1.2 mm. The radial spacing L2 mm between two adjacent electrical connections 142 is 0.4 mm. The ratio L1 / L2 of the maximum radial dimension L1 mm of each electrical connection 142 and the radial spacing L2 mm between two adjacent electrical connections 142 is 3. The central angle α of the sector projection of each welded area 1411 on the reference plane P is 4°. The sum of the central angles α of the sector projections of multiple welded areas 1411 on the reference plane P is... m It is 16°.

[0112] The batteries prepared in the above embodiments and comparative examples were subjected to performance tests. The specific test methods for the test items are as follows:

[0113] 1. Test method for impedance performance of lithium-ion batteries

[0114] At 25℃, the lithium-ion battery was charged to the upper limit voltage using a 1C rate constant current and constant voltage method, allowed to stand for 30 minutes, then discharged to 50% SQC using a 1C rate constant current method, allowed to stand for 60 minutes, and then discharged to 10 seconds using a 3C rate constant current method, allowed to stand for 30 minutes. The DC internal resistance of the lithium-ion battery was then calculated.

[0115] 2. Test methods for the cycle performance of lithium-ion batteries

[0116] At 25°C, the prepared lithium-ion battery was charged to 4.2V at a constant current and constant voltage of 1C, with a cutoff current of 0.05C, and discharged to 2.8V at a constant current of 1C. Cyclic tests were then conducted until the capacity of the lithium-ion battery decayed to 80% of its initial capacity, and the number of cycles was recorded.

[0117] The relevant parameters and test results from the above embodiments and comparative examples are recorded in Table 1 below.

[0118] Table 1

[0119] As can be seen from the data in Table 1, the lithium-ion batteries in Comparative Examples 1 to 8 did not exhibit the corresponding performance and did not meet the requirements.

[0120] Therefore, in the battery cell provided in this application embodiment, by limiting the ratio of the maximum radial dimension L1 mm of each electrical connection 142 to the radial distance L2 mm between two adjacent electrical connection portions 142 to be in the range of 0.01 to 2, limiting the maximum radial dimension L1 mm of each electrical connection portion 142 to be in the range of 0.1 mm to 1 mm, limiting the radial distance L2 mm between two adjacent electrical connection portions 142 to be in the range of 0.5 mm to 10 mm, limiting the central angle α of the sector projection of the welding area 1411 on the reference plane P to be not less than 9°, and limiting the sum of the central angles α of the sector projections of multiple welding areas 1411 on the reference plane P to be α m Within the range of 18° to 360°, the structural dimensions of the electrical connection portion 142 on the current collector 140 are more rationally designed, which optimizes the electronic conduction path in the single cell 100, reduces the impedance of the single cell 100, improves the overall overcurrent performance of the single cell 100, and thus improves the rate performance and cycle performance of the single cell 100.

[0121] The above steps are provided only to help understand the method, structure, and core ideas of this application. Those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A single-cell battery, comprising: The housing (110) has intersecting axial (Z) and radial (X) axes; An electrode assembly (120) is disposed within the housing (110); An end cap (130) is disposed at one end of the housing (110) in the axial direction (Z), and the end cap (130) and the housing (110) are connected; A current collector (140) includes a current collector body (141) and an electrical connection portion (142) connecting the current collector body (141). The current collector body (141) is disposed between the electrode assembly (120) and the end cap (130), and the current collector body (141) is electrically connected to the electrode assembly (120) through the electrical connection portion (142). The current collector body (141) includes a welding area (1411), and the electrical connection part (142) is disposed in the welding area (1411). There are multiple electrical connection parts (142), which are spaced apart in the radial direction (X). In the radial direction (X), the maximum size of each electrical connection part (142) is L1 mm, and the distance between two adjacent electrical connection parts (142) is L2 mm. L1 and L2 satisfy: 0.01≤L1 / L2≤2.

2. The single-cell battery as described in claim 1, wherein, The maximum dimension L1 mm of each of the electrical connections (142) in the radial (X) direction also satisfies: 0.1≤L1≤1.

3. The single-cell battery as described in claim 1, wherein, The distance L2 mm between two adjacent electrical connection parts (142) in the radial (X) direction also satisfies: 0.5≤L2≤10.

4. The single-cell battery as described in claim 1, wherein, The maximum dimension L1 mm of each of the electrical connections (142) in the radial (X) direction also satisfies: 0.1≤L1≤1, and the distance L2 mm between two adjacent electrical connections (142) in the radial (X) direction also satisfies: 0.5≤L2≤10.

5. The single-cell battery according to any one of claims 1 to 4, wherein, The housing (110) also has a reference plane (P) perpendicular to the axial direction (Z). The orthographic projection of the welding area (1411) onto the reference plane (P) is fan-shaped, and the two radii of the welding area (1411) extend along the radial direction (X).

6. The single-cell battery as described in claim 5, wherein, The individual cell also has a circumferential (R) orientation around the axial direction (Z). The plurality of electrical connections (142) within the welding area (1411) extend along the circumferential direction (R), and the curvature of the plurality of electrical connections (142) is consistent.

7. The single-cell battery as described in claim 5, wherein, The central angle of the sector projection of the welding area (1411) on the reference plane (P) is α, and α satisfies: 9°≤α.

8. The single-cell battery as described in claim 5, wherein, The individual cell also has a circumferential (R) orientation around the axial direction (Z). The welding area (1411) is provided in multiple ways. The multiple welding areas (1411) are arranged at intervals along the circumferential direction (R), and the radii of the multiple welding areas (1411) intersect at a common center (Q). The multiple welding areas (1411) are symmetrical about the common center (Q).

9. The single-cell battery as described in claim 8, wherein, The sum of the central angles of the sector projections of the plurality of welding areas (1411) onto the reference plane (P) is α. m α m Satisfy: 18°≤α m ≤360°.

10. The single-cell battery as described in claim 8, wherein, The central angles of the sector projections of the multiple welding areas (1411) on the reference plane (P) are the same.

11. The single-cell battery as described in claim 8, wherein, The central angles of the sector projections of the multiple welding areas (1411) on the reference plane (P) are different.

12. The single-cell battery as described in claim 8, wherein, Each of the electrical connections (142) extends along the circumferential direction (R), and the orthographic projection of each of the electrical connections (142) on the reference plane (P) is an arc shape arranged around the common center (Q), and each of the welding areas (1411) is provided with a plurality of electrical connections (142) spaced apart in the radial direction (X).

13. The single-cell battery as described in claim 12, wherein, In the radial direction (X), the maximum dimension of the electrical connection (142) in the circumferential direction (R) increases in the direction away from the common center (Q).

14. The single-cell battery as claimed in claim 1, wherein, The electrode assembly (120) is welded to the current collector (140) to form the electrical connection (142).

15. A battery pack, comprising: Box; as well as The single-cell battery as described in any one of claims 1 to 14, wherein the single-cell battery is disposed within the housing.

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