Single battery and battery pack

Abstract

The single battery is provided with a first direction, and comprises a shell, a first electrode, a second electrode, a third electrode and a fourth electrode, the electrode assembly is arranged in the shell; the end cover is arranged at one end of the shell and is connected with the shell; the current collecting component comprises a first current collecting part and a second current collecting part which are connected, the first current collecting part is arranged between the end cover and the electrode assembly and electrically connected with the electrode assembly, the first current collecting part and the end cover are arranged in an insulated mode, the second current collecting part extends in the first direction in the direction away from the end cover, and the second current collecting part extends in the direction away from the end cover. And the second current collecting part is arranged between the electrode assembly and the shell and is electrically connected with the shell. According to the invention, the space utilization rate of the electrode assembly in the shell is improved, so that the energy density of the single battery is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a single cell and a battery pack. Background Art

[0002] With the rapid development of mobile phones, laptops, electric vehicles, power tools, and other devices, batteries with high capacity, long cycle life, and high safety performance have been widely used and developed. At the same time, there is an urgent demand for batteries with higher capacity, greater durability, and greater safety. Energy density is one of the core performance characteristics of batteries, so how to improve battery energy density has become a pressing issue. Utility Model Content

[0003] Embodiments of the present application provide a single cell and a battery pack to improve the energy density of the single cell.

[0004] In order to solve the above technical problems, the embodiments of the present application disclose the following technical solutions:

[0005] In one aspect, a single cell battery is provided, having a first orientation, comprising: a housing;

[0006] an electrode assembly disposed in the housing;

[0007] an end cover, disposed at one end of the housing and connected to the housing; and

[0008] The current collecting component includes a first current collecting part and a second current collecting part connected to each other. The first current collecting part is arranged between the end cover and the electrode assembly and is electrically connected to the electrode assembly. The first current collecting part and the end cover are insulated. The second current collecting part extends in a first direction away from the end cover. The second current collecting part is arranged between the electrode assembly and the shell and is electrically connected to the shell.

[0009] In addition to or as an alternative to one or more features disclosed above, the thickness of the second header is L1 mm, the thickness of the housing is L2 mm, and the following relationship is satisfied: 1≤L1 / L2≤1.5.

[0010] In addition to one or more of the features disclosed above, or as an alternative, the thickness L1 mm of the second header further satisfies: 0.1 mm ≤ L1 ≤ 1.5 mm; and / or,

[0011] The thickness L2 mm of the shell also satisfies: 0.1 mm ≤ L2 ≤ 1 mm.

[0012] In addition to or as an alternative to one or more features disclosed above, the thickness of the first header is L3 mm, satisfying: 0.05 mm ≤ L3 ≤ 1 mm.

[0013] In addition to one or more of the features disclosed above, or as an alternative, the maximum outer dimension of the first current collecting portion is D1 mm, the maximum outer dimension of the electrode assembly is D2 mm, and the following conditions are met:

[0014] 1.001≤D1 / D2≤1.1.

[0015] In addition to or as an alternative to one or more features disclosed above, the maximum dimension of the electrode assembly in the first direction is H1 mm, the maximum dimension of the second current collecting portion in the first direction is H2 mm, and 0.01≤H2 / H1≤1 is satisfied.

[0016] In addition to or as an alternative to one or more of the features disclosed above, the second current collecting portion has an extension surface, the extension surface is located on a side of the second current collecting portion facing the inner wall of the housing, and the extension surface extends along the first direction toward a side away from the end cover, the extension surface has a connection area, and the second current collecting portion is electrically connected to the housing through the connection area;

[0017] The maximum area of the connection area is S1 mm 2 , the maximum area of the extended surface is S2 mm 2 , satisfying: 0.3≤S1 / S2≤1.

[0018] In addition to or as an alternative to one or more of the features disclosed above, the present invention further includes: an expansion adhesive layer, at least a portion of which is disposed between the electrode assembly and the second current collecting portion.

[0019] In addition to or as an alternative to one or more of the features disclosed above, the thickness of the expansion adhesive layer is L4 mm, satisfying: 0.01 mm≤L4≤0.5 mm.

[0020] On the other hand, a battery pack is further disclosed. In addition to or as an alternative to one or more of the features disclosed above, the battery pack includes a box; and a single battery as described in any one of the above items, wherein the single battery is arranged in the box.

[0021] One of the above technical solutions has the following advantages or beneficial effects: the present application arranges the first current collecting part of the current collecting component between the end cover and the electrode assembly, and arranges the second current collecting part between the electrode assembly and the shell. Since the second current collecting part extends in the first direction away from the end cover, and has no extension and space occupation in the first direction between the electrode assembly and the end cover, the space occupied by the current collecting component in the first direction inside the shell is reduced, so that more electrode assemblies can be accommodated in the shell, thereby improving the space utilization rate of the electrode assembly in the shell, so as to improve the energy density of the single cell; at the same time, in the present application, the first current collecting part is electrically connected to the electrode assembly, and the second current collecting part is electrically connected to the shell, so that the single cell forms a current path of electrode assembly-first current collecting part-second current collecting part-shell, so that the current path of the single cell when it is working normally is not conducted to the end cover, so that the resistance value of the structural parts when the single cell is working does not include the end cover, effectively reducing the internal resistance of the single cell, reducing the heat generation of the single cell when it is working normally, and improving the performance of the single cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0023] Figure 1 This is a perspective exploded structural view of a single cell provided in accordance with an embodiment of the present application;

[0024] Figure 2 is a partial cross-sectional view of a single cell provided according to an embodiment of the present application;

[0025] Figure 3 is a cross-sectional view of an electrode assembly and a current collecting member provided according to an embodiment of the present application;

[0026] Figure 4 yes Figure 3 A partial enlarged view of point A in the middle.

[0027] Description of reference numerals:

[0028] 100. Single cell;

[0029] 110. Housing;

[0030] 120. Electrode assembly;

[0031] 130, end cap;

[0032] 140. Current collecting member; 141. First current collecting portion; 142. Second current collecting portion; 1421. Extension surface;

[0033] 150. Expanding adhesive layer. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and beneficial effects of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for the purpose of explaining this application and are not intended to limit this application.

[0035] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, the meaning of "multiple" refers to two or more, unless otherwise clearly and specifically defined.

[0036] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, direct connections, or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0037] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0038] Existing large cylindrical batteries have received widespread attention due to their superior performance of low internal resistance and high energy density. At present, after the current collecting plate in a large cylindrical battery is electrically connected to the electrode assembly, it can be overlap-welded to the shell or welded to the end cover. When the current collecting plate is overlap-welded to the shell, the overlap structure on the current collecting plate occupies a large height space, affecting the battery energy density. At the same time, the overlap structure is prone to poor contact with the shell, affecting the welding effect; when the current collecting plate is welded to the end cover, the two are mainly connected by penetration welding. Penetration welding requires a very small gap between the end cover and the current collecting plate, and has high tolerance requirements on the height of the electrode assembly and structural parts. The manufacturing process is relatively difficult.

[0039] In order to solve the above problems, in the embodiments of the present application, referring to Figures 1 to 4 The present application provides a single battery 100, and the single battery 100 has a first direction Z. Exemplarily, the first direction Z is the height direction of the single battery 100 in the present application.

[0040] The single cell 100 may be a secondary battery, which refers to a battery that can be recharged to activate the active material after discharge for continued use. For example, the single cell 100 may be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-metal hydride battery, or a nickel-cadmium battery, but is not limited thereto.

[0041] The single battery 100 may be a cylindrical battery, a prismatic battery, a soft-pack battery, or a battery of other shapes.

[0042] Specifically, the single battery 100 may include a housing 110 , an electrode assembly 120 , an end cap 130 , and a current collecting member 140 .

[0043] Specifically, the electrode assembly 120 is disposed in the shell 110; the end cover 130 is disposed at one end of the shell 110, and the end cover 130 and the shell 110 are connected; the current collecting component 140 is disposed in the shell 110, and the current collecting component 140 is disposed between the end cover 130 and the electrode assembly 120.

[0044] The housing 110 may be made of a strong material such as metal, but is not limited thereto. For example, the housing 110 may be made of an aluminum profile, but is not limited thereto.

[0045] The end cap 130 can be integrally formed with the housing 110, i.e., the end cap 130 and the housing 110 form a one-piece structure. The end cap 130 can also be fixedly connected to the housing 110, for example, by welding or other processes to one end of the housing 110 in the first direction Z. This is not specifically limited in this application and can be specifically configured according to actual circumstances. For example, in this application, the end cap 130 is provided separately from the housing 110, and the end cap 130 and the housing 110 are fixedly welded.

[0046] Among them, the above-mentioned single cell 100 also includes an electrolyte, a pole and other functional components. The electrolyte can be a conventional electrolyte or a special electrolyte with additives added. The electrolyte is used to soak the electrode assembly 120. Among them, the electrode assembly 120 is a component where the electrochemical reaction occurs in the single cell 100, and there can be one or more electrode assemblies. The electrode assembly 120 is mainly formed by winding or stacking a positive electrode sheet, a diaphragm and a negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet with active substances constitute the electrode body, and the parts of the positive electrode sheet and the negative electrode sheet without active substances constitute the tabs. During the charge and discharge process of the single cell 100, the positive electrode active substance and the negative electrode active substance react with the electrolyte, and the tabs are electrically connected to the poles to form a current loop, so that the single cell 100 can be used normally.

[0047] The current collecting component 140 may be a positive electrode current collecting disk or a negative electrode current collecting disk, which is not specifically limited in this application.

[0048] Specifically, the current collecting component 140 includes a first current collecting part 141 and a second current collecting part 142 connected to each other. The first current collecting part 141 is arranged between the end cover 130 and the electrode assembly 120, and the first current collecting part 141 is electrically connected to the electrode assembly 120, and the first current collecting part 141 is insulated from the end cover 130. The second current collecting part 142 extends in the first direction Z in a direction away from the end cover 130, and the second current collecting part 142 is arranged between the electrode assembly 120 and the shell 110, and the second current collecting part 142 is electrically connected to the shell 110, and the second current collecting part 142 is insulated from the electrode assembly 120 to form a current path of the electrode assembly 120-first current collecting part 141-second current collecting part 142-shell 110.

[0049] The first collecting part 141 may be circular, or the central area of the first collecting part 141 may be hollow, so that the first collecting part 141 is in a circular ring shape. This is not specifically limited in the present application and can be selected according to actual circumstances.

[0050] Among them, the first collecting part 141 can be integrally formed with the second collecting part 142, that is, the first collecting part 141 and the second collecting part 142 are an integrated structure; the first collecting part 141 can also be fixedly connected to the second collecting part 142, for example, the first collecting part 141 is fixedly connected to the second collecting part 142 by welding or other processes. This is not specifically limited in this application and can be specifically set according to actual circumstances. For example, in this application, a die-casting mold can be used to integrally cast the first collecting part 141 and the second collecting part 142 to improve the molding efficiency of the collecting component 140, thereby improving the overall assembly efficiency of the single cell 100.

[0051] The first current collecting section 141 and the second current collecting section 142 may be made of a variety of materials, and the materials of the first current collecting section 141 and the second current collecting section 142 may be the same or different. For example, the first current collecting section 141 and the second current collecting section 142 may be made of any conductive material such as copper, iron, aluminum, steel, or aluminum alloy, but are not limited thereto.

[0052] Among them, there can be multiple ways of connecting the first collecting part 141 and the electrode assembly 120, exemplarily: welding, abutment or connection through conductive glue, etc. Similarly, there can be multiple ways of connecting the second collecting part 142 and the shell 110, exemplarily: welding, abutment or connection through conductive glue, etc.

[0053] Different regions of the second current collecting portion 142 may be connected to the housing 110 in the same or different ways. For example, in this application, the first current collecting portion 141 is fixed to the electrode assembly 120 by laser welding, and the second current collecting portion 142 is fixed to the housing 110 by laser welding.

[0054] The conductivity of the second current collecting portion 142 may be greater than that of the housing 110; the conductivity of the second current collecting portion 142 may also be less than that of the housing 110; or the conductivity of the second current collecting portion 142 may be the same as that of the housing 110. This is not specifically limited in the present application and may be set according to actual circumstances.

[0055] It can be understood that the present application arranges the first collecting portion 141 of the current collecting member 140 between the end cover 130 and the electrode assembly 120, and arranges the second collecting portion 142 between the electrode assembly 120 and the shell 110. Since the second collecting portion 142 extends in the first direction Z in the direction away from the end cover 130, and has no extension and space occupation in the first direction Z between the electrode assembly 120 and the end cover 130, the occupation of the space in the first direction Z inside the shell 110 by the current collecting member 140 is reduced, so that more electrode assemblies 120 can be accommodated in the shell 110, thereby improving the space utilization rate of the electrode assembly 120 in the shell 110, so as to improve the energy density of the single battery 100; at the same time, in the present application, the first collecting portion 141 is electrically connected to the electrode assembly 120, and the second collecting portion 142 is electrically connected to the shell 110. 0 electrical connection, so that the single battery 100 forms a current path of the electrode assembly 120-first current collecting part 141-second current collecting part 142-housing 110, thereby making the current path of the single battery 100 during normal operation not conductive to the end cover 130, thereby making the resistance value of the structural parts of the single battery 100 during operation not include the end cover 130, effectively reducing the internal resistance of the single battery 100, reducing the heat generation of the single battery 100 during normal operation, and improving the performance of the single battery 100; at the same time, the current collecting member 140 in the present application adopts the above-mentioned connection arrangement method, so that there is no requirement for the tolerance of the electrode assembly 120 and other structural parts in the single battery 100, reducing the difficulty of the production process of the single battery 100, improving the manufacturability of the single battery 100, and thereby improving the production efficiency of the single battery 100.

[0056] In one embodiment, the thickness of the second header 142 at different locations may be uniform or non-uniform. When the second header 142 has a uniform thickness, the thickness ratio of the second header to the housing 110 is fixed. If the second header 142 has a non-uniform thickness, the thickness ratio is a range of values rather than a single point.

[0057] For example, in the present application, the thicknesses of different positions of the second collecting portion 142 are consistent. Even if they are inconsistent, there are small thickness differences due to processing.

[0058] Specifically, the thickness of the second collecting section 142 is L1 mm, and the thickness of the shell 110 is L2 mm, satisfying: 1≤L1 / L2≤1.5. Specifically, when the second collecting section 142 is a structure with uneven thickness, the ratio of the thickness L1 mm of the second collecting section 142 to the thickness L2 mm of the shell 110 can be controlled within the range of 1 to 1.1, 1.1 to 1.3, 1.2 to 1.4, or 1.3 to 1.5. When the second collecting section 142 is a structure with uniform thickness, L1 / L2 can be 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, or 1.5. It is worth noting that the specific values of L1 / L2 are given for example only, and any value within the range of 1 to 1.5 of the thickness difference is within the protection scope of this application.

[0059] The thickness L1 mm of the second current collecting portion 142 can be determined by disassembling the actual single battery 100, measuring the distance between two opposing surfaces of the second current collecting portion 142 of the current collecting member 140 in the thickness direction multiple times using a measuring tool, and calculating the average value. The measuring tool can be, but is not limited to, a ruler, a vernier caliper, or other dimensional measuring instrument.

[0060] The thickness L2 mm of the housing 110 can be determined by disassembling the actual single battery 100, measuring the distance between two opposing surfaces of the sidewall of the housing 110 in the thickness direction multiple times using a measuring tool, and calculating the average value. The measuring tool can be, but is not limited to, a ruler, a vernier caliper, or other dimensional measuring instrument.

[0061] It can be understood that the present application reasonably designs the thickness structure of the second collecting part 142 by limiting the ratio of the thickness L1 mm of the second collecting part 142 to the thickness L2 mm of the shell 110 within the range of 1 to 1.5, so as to further reduce the occupation of the internal space of the shell 110 by the collecting component 140, so that more electrode assemblies 120 can be accommodated in the shell 110, thereby improving the space utilization of the electrode assembly 120 in the shell 110, and ultimately improving the energy density of the single battery 100.

[0062] In one embodiment, the thickness L1 mm of the second collecting portion 142 also satisfies: 0.1 mm ≤ L1 ≤ 1.5 mm. Specifically, when the second collecting portion 142 is a structure with uneven thickness, the thickness L1 mm of the second collecting portion 142 can be controlled within the range of 0.1 mm to 0.5 mm, 0.3 mm to 0.8 mm, 0.5 mm to 1 mm, or 1 mm to 1.5 mm. When the second collecting portion 142 is a structure with uniform thickness, the thickness L1 mm of the second collecting portion 142 can be 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1.1 mm, 1.3 mm, or 1.5 mm. It is worth noting that the specific value of L1 mm is given for example only, and any value within the range of 0.1 mm to 1.5 mm is within the protection scope of this application.

[0063] The present application limits the thickness L1 mm of the second current collecting portion 142 to be within the range of 0.1 mm to 1.5 mm, so as to further rationally design the thickness structure of the second current collecting portion 142, thereby further reducing the occupation of the internal space of the shell 110 by the current collecting component 140, so that more electrode assemblies 120 can be accommodated in the shell 110, thereby improving the space utilization rate of the electrode assembly 120 in the shell 110, and ultimately improving the energy density of the single battery 100.

[0064] In one embodiment, the thickness L2 mm of the housing 110 further satisfies the following: 0.1 mm ≤ L2 ≤ 1 mm. That is, the thickness L2 mm of the housing 110 can be controlled within the range of 0.1 mm to 1 mm. For example, the thickness L2 mm of the housing 110 can be within a range of 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, or any two thereof. The above specific values of L2 mm are provided for example only; any value within the range of 0.1 mm to 1 mm is within the scope of protection of this application. By limiting the thickness L2 mm of the housing 110 to within the range of 0.1 mm to 1 mm, this application designs the thickness structure of the housing 110 to ensure that the housing 110 has a certain structural strength, thereby ensuring that the housing 110 has a good protective function and improving the safety performance of the single battery 100.

[0065] In one embodiment, the thickness of the first collecting part 141 is also designed in the present application. Specifically, the thickness of the first collecting part 141 is L3 mm, which satisfies: 0.05 mm ≤ L3 ≤ 1 mm. That is, the thickness L3 mm of the first collecting part 141 can be controlled within the range of 0.05 mm to 1 mm. For example, the thickness L3 mm of the first collecting part 141 can be 0.05 mm, 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, or a range consisting of any two of them. The above specific numerical values of L3 mm are given for example only, and any value within the range of 0.05 mm to 1 mm is within the protection scope of the present application. The present application limits the thickness L3 mm of the first current collecting portion 141 to be within the range of 0.05 mm to 1 mm, thereby rationally designing the thickness of the first current collecting portion 141 and reducing the space occupied by the first current collecting portion 141 of the current collecting component 140 in the internal space of the shell 110. This further allows more electrode assemblies 120 to be accommodated in the shell 110, thereby improving the space utilization rate of the electrode assembly 120 in the shell 110 and ultimately improving the energy density of the single battery 100.

[0066] The thickness L3 mm of the first current collecting portion 141 can be determined by disassembling the actual single battery 100, measuring the distance between two opposing surfaces of the first current collecting portion 141 of the current collecting member 140 in the thickness direction multiple times using a measuring tool, and calculating the average value. The measuring tool can be, but is not limited to, a ruler, a vernier caliper, or other dimensional measuring instrument.

[0067] Furthermore, the thickness L3 mm of the first collecting section 141 also satisfies the following: 0.1 mm ≤ L3 ≤ 0.5 mm. That is, the thickness L3 mm of the first collecting section 141 can be controlled within the range of 0.1 mm to 0.5 mm. For example, the thickness L3 mm of the first collecting section 141 can be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, or 0.5 mm, or a range consisting of any two of them. The above specific values of L3 mm are given for example only, and any value within the range of 0.1 mm to 0.5 mm is within the scope of protection of this application. The present application limits the thickness L3 mm of the first current collecting portion 141 to be within the range of 0.1 mm to 0.5 mm, so as to further rationally design the thickness dimension of the first current collecting portion 141, reduce the occupation of the internal space of the shell 110 by the first current collecting portion 141 of the current collecting component 140, and further allow more electrode assemblies 120 to be accommodated in the shell 110, thereby improving the space utilization rate of the electrode assembly 120 in the shell 110, and ultimately improving the energy density of the single battery 100.

[0068] In one embodiment, the maximum outer dimension of the first current collecting portion 141 is D1 mm, and the maximum outer dimension of the electrode assembly 120 is D2 mm, satisfying: 1.001≤D1 / D2≤1.1. That is, the ratio of the maximum outer dimension D1 mm of the first current collecting portion 141 to the maximum outer dimension D2 mm of the electrode assembly 120 can be controlled within the range of 1.001 to 1.1. For example, D1 / D2 can be 1.001, 1.005, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09 or 1.1, or a range consisting of any two of them. The above specific values of D1 / D2 are given for example only, and any value within the range of 1.001 to 1.1 is within the scope of protection of this application. The present application limits the ratio of the maximum outer contour dimension D1 mm of the first current collecting part 141 to the maximum outer contour dimension D2 mm of the electrode assembly 120 within the range of 1.001 to 1.1, so as to reasonably design the structural dimensions of the first current collecting part 141, thereby ensuring that the first current collecting part 141 has sufficient contact area to connect with the electrode assembly 120, ensuring that the current collecting component 140 can be fully utilized for heat dissipation when the single cell 100 is working normally, thereby improving the heat dissipation performance of the single cell 100 and ultimately improving the safety performance of the single cell 100.

[0069] The maximum outer dimension D1 mm of the first current collecting section 141 can be obtained by disassembling the actual single battery cell 100, measuring the outer dimensions of the first current collecting section 141 at different locations in the first direction Z multiple times using a measuring tool, and calculating the average value. For example, the maximum outer dimension D1 mm of the first current collecting section 141 can be obtained by measuring the outer dimensions of the two opposite ends of the first current collecting section 141 in the first direction Z, as well as the outer dimensions of the central region of the first current collecting section 141 in the first direction Z, and calculating the average value to obtain the maximum outer dimension D1 mm of the first current collecting section 141. The measuring tool can be, but is not limited to, a ruler, a vernier caliper, or other dimensional measuring instrument.

[0070] The maximum outer dimension D2 mm of the electrode assembly 120 can be obtained by disassembling the actual single battery cell 100, measuring the outer dimensions of the electrode assembly 120 at different locations in the first direction Z multiple times using a measuring tool, and calculating the average value. For example, the maximum outer dimension D2 mm of the electrode assembly 120 can be obtained by measuring the outer dimensions of two opposite ends of the electrode assembly 120 in the first direction Z, as well as the outer dimensions of the central region of the electrode assembly 120 in the first direction Z, and calculating the average value to obtain the maximum outer dimension D2 mm of the electrode assembly 120. The measuring tool can be, but is not limited to, a ruler, a vernier caliper, or other dimensional measuring instrument.

[0071] Furthermore, the maximum outer dimension of the first current collecting portion 141 is D1 mm, and the maximum outer dimension of the electrode assembly 120 is D2 mm, satisfying: 1.005≤D1 / D2≤1.05. That is, the ratio of the maximum outer dimension D1 mm of the first current collecting portion 141 to the maximum outer dimension D2 mm of the electrode assembly 120 can be controlled within the range of 1.005 to 1.05. For example, D1 / D2 can be one of 1.005, 1.01, 1.015, 1.02, 1.025, 1.03, 1.035, 1.04, 1.045 or 1.05, or a range consisting of any two of them. The above specific values of D1 / D2 are given for example only, and any value within the range of 1.005 to 1.05 is within the scope of protection of this application. The present application limits the ratio of the maximum outer contour dimension D1 mm of the first current collecting part 141 to the maximum outer contour dimension D2 mm of the electrode assembly 120 within the range of 1.005 to 1.05, so as to further rationally design the structural dimensions of the first current collecting part 141, ensure that the first current collecting part 141 has sufficient contact area to connect with the electrode assembly 120, and ensure that the current collecting component 140 can be fully utilized for heat dissipation when the single cell 100 is working normally, thereby improving the heat dissipation performance of the single cell 100 and ultimately improving the safety performance of the single cell 100.

[0072] In one embodiment, the maximum dimension of the electrode assembly 120 in the first direction Z is H1 mm, and the maximum dimension of the second current collecting portion 142 in the first direction Z is H2 mm, satisfying: 0.01≤H2 / H1≤1. That is, the ratio of the maximum dimension H2 mm of the second current collecting portion 142 in the first direction Z to the maximum dimension H1 mm of the electrode assembly 120 in the first direction Z can be controlled within the range of 0.01 to 1. For example, H2 / H1 can be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, or a range consisting of any two of them. The above specific values of H2 / H1 are given for example only, and any value within the range of 0.01 to 1 is within the scope of protection of this application. The present application limits the ratio of the maximum dimension H2 mm of the second current collecting portion 142 in the first direction Z to the maximum dimension H1 mm of the electrode assembly 120 in the first direction Z to be within the range of 0.01 to 1, so as to reasonably design the structural dimensions of the second current collecting portion 142, ensure that the second current collecting portion 142 has sufficient contact area to be connected with the shell 110, further ensure that the current collecting component 140 can be fully utilized for heat dissipation when the single cell 100 is working normally, thereby improving the heat dissipation performance of the single cell 100 and ultimately improving the safety performance of the single cell 100.

[0073] The maximum dimension H1 mm of the electrode assembly 120 in the first direction Z can be obtained by disassembling the actual single battery cell 100, measuring the distance between two opposing surfaces of the electrode assembly 120 in the first direction Z multiple times using a measuring tool, and calculating the average value. The measuring tool can be, but is not limited to, a ruler, a vernier caliper, or other dimension measuring instrument.

[0074] The maximum dimension H2 mm of the second current collecting portion 142 in the first direction Z can be obtained by disassembling the actual single battery 100, measuring the distance between two opposing surfaces of the second current collecting portion 142 of the current collecting member 140 in the first direction Z multiple times using a measuring tool, and calculating the average value. The measuring tool can be any one of, but is not limited to, a ruler, a vernier caliper, or other dimensional measuring instrument.

[0075] In one embodiment, the maximum dimension H1 mm of the electrode assembly 120 in the first direction Z and the maximum dimension H2 mm of the second current collecting portion 142 in the first direction Z also satisfy: 0.3≤H2 / H1≤0.9. That is, the ratio of the maximum dimension H2 mm of the second current collecting portion 142 in the first direction Z to the maximum dimension H1 mm of the electrode assembly 120 in the first direction Z can be controlled within the range of 0.3 to 0.9. For example, H2 / H1 can be 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85 or 0.9, or a range consisting of any two of them. The above specific values of H2 / H1 are given for example only, and any value within the range of 0.3 to 0.9 is within the scope of protection of this application. The present application limits the ratio of the maximum dimension H2 mm of the second current collecting portion 142 in the first direction Z to the maximum dimension H1 mm of the electrode assembly 120 in the first direction Z to be within the range of 0.3 to 0.9, so as to further rationally design the structural dimensions of the second current collecting portion 142, ensure that the second current collecting portion 142 has sufficient contact area to be connected with the shell 110, and ensure that the current collecting component 140 can be fully utilized for heat dissipation when the single cell 100 is working normally, thereby improving the heat dissipation performance of the single cell 100 and ultimately improving the safety performance of the single cell 100.

[0076] In one embodiment, the second collecting portion 142 has an extension surface 1421, which is located on the side of the second collecting portion 142 facing the inner wall of the shell 110, and the extension surface 1421 extends along the first direction Z toward the side away from the end cover 130, and the extension surface 1421 has a connection area 14211, and the second collecting portion 142 is electrically connected to the shell 110 through the connection area 14211.

[0077] The extension surface 1421 in this application is the outer surface of the second current collecting portion 142 that faces the inner wall of the housing 110, and the connection region 14211 of the extension surface 1421 can be directly connected to the housing 110, welded, or connected using a conductive adhesive. For example, in this application, the connection region 14211 of the extension surface 1421 is welded to the housing 110, and the connection region 14211 is a welding region.

[0078] Specifically, the maximum area of the connection region 14211 is S1 mm 2 , the maximum area of the extension surface 1421 is S2mm 2 , satisfying: 0.3≤S1 / S2≤1. That is, the maximum area of the connection area 14211 is S1 mm 2 and the maximum area S2 mm of the extension surface 1421 2The ratio of S1 / S2 can be controlled within the range of 0.3 to 1. For example, S1 / S2 can be in the range of 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, or any two thereof. The above specific values of S1 / S2 are given for example only, and any value within the range of 0.3 to 1 is within the scope of protection of this application.

[0079] This application defines the maximum area of the connection area 14211 as S1 mm 2 and the maximum area of the extension surface 1421 is S2mm 2 The ratio is within the range of 0.3 to 1, so as to further reasonably design the structural dimensions of the second current collecting part 142, ensure that the second current collecting part 142 is fully in contact and connected with the shell 110, and ensure that the current collecting component 140 can be fully utilized for heat dissipation when the single battery 100 is working normally, thereby improving the heat dissipation performance of the single battery 100 and ultimately improving the safety performance of the single battery 100.

[0080] Among them, the maximum area of the extension surface 1421 is S2 mm 2 After disassembling the actual single battery 100, the second current collecting portion 142 of the current collecting member 140 is flattened, and the image area of the extension surface 1421 of the second current collecting portion 142 is measured multiple times using a projection measurement device (such as a digital microscope or an image measuring instrument), thereby obtaining the maximum area S2 mm of the extension surface 1421. 2 , but not limited to this.

[0081] Maximum area of the connection area 14211 S1 mm 2 After disassembling the actual single battery 100, the second current collecting portion 142 of the current collecting member 140 is flattened, and the image area of the connection area 14211 of the extension surface 1421 of the second current collecting portion 142 is measured multiple times using a projection measurement device (such as a digital microscope or an image measuring instrument), thereby obtaining the maximum area S1 mm of the connection area 14211. 2 , but not limited to this.

[0082] Furthermore, the maximum area of the connection region 14211 is S1 mm 2 and the maximum area of the extension surface 1421 is S2mm 2 It also satisfies: 0.9≤S1 / S2≤1. That is, the maximum area of the connection area 14211 is S1 mm 2 and the maximum area S2 mm of the extension surface 1421 2The ratio of S1 / S2 can be controlled within the range of 0.9 to 1. For example, S1 / S2 can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or 1, or a range consisting of any two of them. The above specific values of S1 / S2 are given for example only, and any value within the range of 0.9 to 1 is within the scope of protection of this application.

[0083] This application defines the maximum area of the connection area 14211 as S1 mm 2 and the maximum area of the extension surface 1421 is S2mm 2 The ratio is within the range of 0.9 to 1, so as to further reasonably design the structural dimensions of the second current collecting part 142, ensure that the second current collecting part 142 is fully in contact and connected with the shell 110, and ensure that the current collecting component 140 can be fully utilized for heat dissipation when the single battery 100 is working normally, thereby improving the heat dissipation performance of the single battery 100 and ultimately improving the safety performance of the single battery 100.

[0084] In one embodiment, the single battery 100 further includes an expandable adhesive layer 150 , at least a portion of which is disposed between the electrode assembly 120 and the second current collecting portion 142 , to ensure that the second current collecting portion 142 is in contact and connected to the housing 110 after the expandable adhesive layer 150 expands, thereby achieving electrical conduction therebetween.

[0085] Insulating material may be added to the expansion adhesive layer 150 to ensure that the expansion adhesive layer 150 has an insulating function, thereby achieving an insulating setting between the second current collecting part 142 and the electrode assembly 120 and avoiding a short circuit caused by direct contact between the second current collecting part 142 and the electrode assembly 120 .

[0086] In one embodiment, the thickness of the expandable adhesive layer 150 is L4 mm, satisfying the following condition: 0.01 mm ≤ L4 ≤ 0.5 mm. That is, the thickness L4 mm of the expandable adhesive layer 150 can be controlled within the range of 0.01 mm to 0.5 mm. For example, the thickness L4 mm of the expandable adhesive layer 150 can be in the range of 0.01 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, or 0.5 mm, or any two thereof. The above specific values of L4 mm are provided for example only; any value within the range of 0.01 mm to 0.5 mm is within the scope of protection of this application. The present application limits the thickness L4 mm of the expansion adhesive layer 150 to a range of 0.01 mm to 0.5 mm, thereby rationally designing the structural dimensions of the expansion adhesive layer 150 , reducing the internal space occupied by the expansion adhesive layer 150 , further allowing more electrode assemblies 120 to be accommodated in the housing 110 , thereby improving the space utilization of the electrode assemblies 120 in the housing 110 , and ultimately improving the energy density of the single battery 100 .

[0087] The thickness L4 mm of the expandable adhesive layer 150 can be determined by disassembling the actual single battery 100, measuring the distance between two opposing surfaces of the expandable adhesive layer 150 with the thickness L4 mm multiple times using a measuring tool, and calculating the average value. The measuring tool can be, but is not limited to, a ruler, a vernier caliper, or other dimension measuring instrument.

[0088] Furthermore, the thickness L4 mm of the expandable adhesive layer 150 also satisfies the following: 0.05 mm ≤ L4 ≤ 0.3 mm. That is, the thickness L4 mm of the expandable adhesive layer 150 can be controlled within the range of 0.05 mm to 0.3 mm. For example, the thickness L4 mm of the expandable adhesive layer 150 can be in the range of 0.05 mm, 0.075 mm, 0.1 mm, 0.125 mm, 0.15 mm, 0.175 mm, 0.2 mm, 0.225 mm, 0.25 mm, 0.275 mm, or 0.3 mm, or any two thereof. The above specific values of L4 mm are provided for illustrative purposes only; any value within the range of 0.05 mm to 0.3 mm is within the scope of protection of this application. The present application limits the thickness L4 mm of the expandable adhesive layer 150 to a range of 0.05 mm to 0.3 mm, thereby further rationally designing the structural dimensions of the expandable adhesive layer 150 , reducing the internal space occupied by the expandable adhesive layer 150 , and further allowing more electrode assemblies 120 to be accommodated in the housing 110 , thereby improving the space utilization of the electrode assemblies 120 in the housing 110 and ultimately increasing the energy density of the single battery 100 .

[0089] On the other hand, in an embodiment of the present application, the present application further provides a battery pack, comprising: a box body; and a single cell 100 as described in any of the above embodiments, wherein the single cell 100 is disposed in the box body.

[0090] On the other hand, in an embodiment of the present application, the present application further provides an electrical device including the battery pack described above, which serves as a power supply for the electrical device. The electrical device described above may be, but is not limited to, a mobile device (e.g., a mobile phone, a laptop computer, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0091] To better understand the technical solution of the present application, a lithium-ion battery is used as an example for further explanation.

[0092] This embodiment provides a method for preparing a lithium-ion battery, and the specific process is as follows:

[0093] 1. Preparation of positive electrode

[0094] The positive electrode active material is lithium iron phosphate, the conductive agent is conductive carbon black SP, and the binder is PVDF in a mass ratio of 96:2:2, and then NMP is added as a solvent to mix. The mixture is stirred under vacuum until the system becomes uniform to obtain a positive electrode slurry; the positive electrode slurry is evenly coated on both sides of the positive electrode current collector aluminum foil, and then transferred to a 120°C oven for drying, and then rolled, slit, and cut into pieces to obtain a positive electrode sheet.

[0095] 2. Preparation of negative electrode sheet

[0096] The negative electrode active material graphite, the conductive agent conductive carbon black SP, the thickener CMC, and the binder SBR are mixed in a mass ratio of 96.2:1.2:1.2:1.4, and then deionized water is added as a solvent to mix. The mixture is stirred under vacuum until the system becomes uniform to obtain a negative electrode slurry; the negative electrode slurry is evenly coated on both sides of the negative electrode current collector copper foil, and then transferred to a 110°C oven for drying, and then rolled, slit, and cut into pieces to obtain a negative electrode sheet.

[0097] 3. Preparation of electrolyte

[0098] 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 evenly, and then vinylene carbonate, vinyl sulfate, and lithium difluorophosphate were added to prepare an electrolyte.

[0099] 4. Preparation of diaphragm

[0100] PP film is used as the separator.

[0101] 5. Preparation of lithium-ion batteries

[0102] After drying, the negative and positive electrode sheets prepared by the above steps are wound together with the separator using a winding machine to prepare a wound electrode roll. The positive and negative electrode tabs are welded to the end caps, and the welded electrode assembly with the top cover is placed in an aluminum shell for packaging. The lithium-ion battery is obtained by pouring electrolyte and forming a constant capacity.

[0103] The lithium-ion batteries of the embodiments and comparative examples were all prepared according to the above-mentioned preparation method. The structural dimensions and performance test data of the embodiments and comparative examples are shown in Tables 1 and 2.

[0104] Among them, Examples 1 to 18 in Table 1 were all prepared according to the above method. The differences between Examples 2 to 18 and Example 1 are: changes in the values of L1, L2, H1, H2, H2 / H1, S1, S2, and S1 / S2.

[0105] In Example 1 and Examples 19 to 35 in Table 2, lithium-ion batteries were prepared according to the above method. The differences between Examples 19 to 35 and Example 1 are: changes in the values of L3, D1, D2, D1 / D2 and L4.

[0106] The batteries prepared in the above examples and comparative examples were subjected to performance tests. The specific test items were as follows:

[0107] 1. Test method for heat dissipation performance of lithium-ion batteries:

[0108] At 25°C, the lithium-ion battery was allowed to stand for 30 minutes, then discharged at a constant current rate of 1C, allowed to stand for 10 minutes, and then charged at a constant current and constant voltage rate of 1C. After 10 cycles of charge and discharge, the maximum temperature rise on the surface of the lithium-ion battery was tested.

[0109] 2. Test method for energy density of lithium-ion batteries:

[0110] At 25°C, the lithium-ion battery was allowed to stand for 30 minutes, charged to the cut-off voltage with a current of 1C, allowed to stand for 30 minutes, and then discharged to the cut-off voltage with a current of 1C, and the actual discharge energy was recorded; the lithium-ion battery was weighed using an electronic balance; the ratio of the 1C actual discharge energy to the weight is the actual energy density of the lithium-ion battery.

[0111] The relevant parameters and test results in the above embodiments and comparative examples are recorded in Table 1.

[0112] Table 1 Parameters and test results of Examples 1 to 18

[0113]

[0114] From the data in Table 1, it can be seen that in Example 17, although the energy density of the lithium-ion battery is relatively high, the maximum surface temperature rise of the lithium-ion battery is also relatively high, and the lithium-ion battery does not exhibit corresponding heat dissipation performance, which does not meet the requirements; in Example 18, although the heat dissipation performance of the lithium-ion battery is relatively good, the density of the lithium-ion battery is relatively low, and the lithium-ion battery does not exhibit corresponding performance, which does not meet the requirements.

[0115] It can be seen that the present application reasonably designs the thickness structure of the second current collecting portion 142 by limiting the ratio of the thickness L1 mm of the second current collecting portion 142 to the thickness L2 mm of the shell 110 within the range of 1 to 1.5, limiting the thickness L1 mm of the second current collecting portion 142 to the range of 0.1 mm to 1.5 mm, and limiting the thickness L2 mm of the shell 110 to the range of 0.1 mm to 1 mm, so as to further reduce the occupation of the internal space of the shell 110 by the current collecting member 140, so that more electrode assemblies 120 can be accommodated in the shell 110, thereby improving the space utilization rate of the electrode assembly 120 in the shell 110, and ultimately improving the energy density of the single battery 100; at the same time, limiting the ratio of the maximum dimension H2 mm of the second current collecting portion 142 in the first direction Z to the maximum dimension H1 mm of the electrode assembly 120 in the first direction Z to the range of 0.01 to 1, and limiting the maximum area S1 mm of the connection area 14211 2 and the maximum area S2 mm of the extension surface 1421 2 The ratio is within the range of 0.3 to 1, so as to further reasonably design the structural dimensions of the second current collecting part 142, ensure that the second current collecting part 142 has sufficient contact area to connect with the shell 110, and further ensure that the current collecting component 140 can be fully utilized for heat dissipation when the single cell 100 is working normally, thereby improving the heat dissipation performance of the single cell 100 and ultimately improving the safety performance of the single cell 100.

[0116] Table 2 Parameters and test results of Example 1 and Examples 19 to 35

[0117]

[0118] It can be seen from the data in Table 2 that: in Example 34, although the energy density of the lithium-ion battery is relatively high, the maximum surface temperature rise of the lithium-ion battery is also relatively high, and the lithium-ion battery does not exhibit corresponding heat dissipation performance, which does not meet the requirements; in Example 35, although the heat dissipation performance of the lithium-ion battery is relatively good, the density of the lithium-ion battery is relatively low, and the lithium-ion battery does not exhibit corresponding performance, which does not meet the requirements.

[0119] It can be seen that the present application limits the thickness L3 mm of the first current collecting part 141 to be within the range of 0.05 mm to 1 mm and limits the thickness L4 mm of the expansion adhesive layer 150 to be within the range of 0.01 mm to 0.5 mm, so that more electrode assemblies 120 can be accommodated in the shell 110, thereby improving the space utilization of the electrode assembly 120 in the shell 110, and ultimately improving the energy density of the single battery 100; at the same time, the ratio of the maximum outer contour dimension D1 mm of the first current collecting part 141 to the maximum outer contour dimension D2 mm of the electrode assembly 120 is limited to the range of 1.001 to 1.1, so as to reasonably design the structural dimensions of the first current collecting part 141, to ensure that the first current collecting part 141 has sufficient contact area to connect with the electrode assembly 120, to ensure that the current collecting component 140 can be fully utilized for heat dissipation when the single battery 100 is working normally, thereby improving the heat dissipation performance of the single battery 100, and ultimately improving the safety performance of the single battery 100.

[0120] The above steps are merely provided to help understand the method, structure, and core concept of the present application. A person skilled in the art may make several improvements and modifications to the present application without departing from the principles of the present application, and such improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A single battery having a first direction, characterized in that: include: case; an electrode assembly, disposed in the housing; an end cover, disposed at one end of the housing and connected to the housing; as well as The current collecting component includes a first current collecting part and a second current collecting part connected to each other, the first current collecting part is arranged between the end cover and the electrode assembly, and is electrically connected to the electrode assembly, the first current collecting part and the end cover are insulated, the second current collecting part extends in the first direction away from the end cover, the second current collecting part is arranged between the electrode assembly and the shell, and is electrically connected to the shell.

2. The single cell according to claim 1, wherein: The thickness of the second collecting portion is L1 mm, and the thickness of the shell is L2 mm, satisfying: 1≤L1 / L2≤1.

5.

3. The single cell according to claim 2, wherein: The thickness L1mm of the second current collecting portion also satisfies: 0.1mm≤L1≤1.5mm; and / or, The thickness L2 mm of the shell also satisfies: 0.1 mm ≤ L2 ≤ 1 mm.

4. The single cell according to any one of claims 1 to 3, wherein: The thickness of the first collecting portion is L3 mm, which satisfies the following conditions: 0.05 mm ≤ L3 ≤ 1 mm.

5. The single cell according to any one of claims 1 to 3, wherein: The maximum outer dimension of the first current collecting portion is D1 mm, and the maximum outer dimension of the electrode assembly is D2 mm, satisfying the following: 1.001≤D1 / D2≤1.

1.

6. The single cell according to any one of claims 1 to 3, wherein: The maximum dimension of the electrode assembly in the first direction is H1 mm, and the maximum dimension of the second current collecting portion in the first direction is H2 mm, satisfying the following: 0.01≤H2 / H1≤1.

7. The single cell according to any one of claims 1 to 3, wherein: The second current collecting portion has an extension surface, the extension surface is located on a side of the second current collecting portion facing the inner wall of the shell, and the extension surface extends along the first direction toward a side away from the end cover, the extension surface has a connection area, and the second current collecting portion is electrically connected to the shell through the connection area; The maximum area of the connection area is S1 mm 2 The maximum area of the extension surface is S2 mm 2 , satisfying: 0.3≤S1 / S2≤1.

8. The single cell according to any one of claims 1 to 3, wherein: Also includes: The expansion adhesive layer, at least a portion of which is disposed between the electrode assembly and the second current collecting portion.

9. The single cell according to claim 8, wherein: The thickness of the expansion adhesive layer is L4 mm, satisfying the following conditions: 0.01 mm ≤ L4 ≤ 0.5 mm.

10. A battery pack, characterized in that: include: Box; as well as The single cell according to any one of claims 1 to 9, wherein the single cell is disposed in the box.

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