Single battery and battery pack

Abstract

The embodiment of the utility model discloses a single battery and a battery pack, and belongs to the technical field of batteries. The single battery has an axial direction and a reference plane vertical to the axial direction, and comprises a shell; the end cover is arranged at one end, in the axial direction, of the shell; the electrode assembly is arranged in the shell and comprises an electrode main body, a first electrode lug and a second electrode lug, the first electrode lug and the second electrode lug are both arranged at the end part, close to the end cover, of the electrode main body in the axial direction, the polarity of the first electrode lug is opposite to that of the second electrode lug, and the first electrode lug and the second electrode lug are arranged at an interval; the orthographic projection area of the first tab on the reference plane is S1 mm < 2 >, the orthographic projection area of the second tab on the reference plane is S2 mm < 2 >, and S2 / S1 is larger than or equal to 0.3 and smaller than or equal to 1.14. According to the battery cell, the over-current capability of the first tab and the over-current capability of the second tab can be ensured to be equivalent, so that an electronic conduction path in the battery cell is optimized, and the power performance of the battery cell 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. Power performance is one of the core performance characteristics of batteries, so how to improve battery power performance 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 power performance 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 battery is provided, having an axial direction and a reference plane perpendicular to the axial direction, comprising:

[0006] case;

[0007] an end cover, disposed at one end of the housing in the axial direction;

[0008] A pole, wherein the pole is provided on the end cover, and the pole and the end cover are insulated; and

[0009] an electrode assembly disposed in the housing, the electrode assembly comprising an electrode body, a first electrode tab, and a second electrode tab, wherein the first electrode tab and the second electrode tab are both disposed at an end of the electrode body in the axial direction close to the end cap, the polarity of the first electrode tab is opposite to the polarity of the second electrode tab, the first electrode tab is electrically connected to the electrode post, the second electrode tab is electrically connected to the end cap, and the first electrode tab and the second electrode tab are spaced apart;

[0010] The orthographic projection area of the first tab on the reference plane is S1 mm 2 The orthographic projection area of the second tab on the reference plane is S2 mm 2 , satisfying: 0.3≤S2 / S1≤1.14.

[0011] In addition to or as an alternative to one or more features disclosed above, the first pole lug and the second pole lug both extend toward the end cover; the first pole lug and the second pole lug are both annularly arranged, and the second pole lug surrounds the outer circumference of the first pole lug.

[0012] In addition to or as an alternative to one or more of the features disclosed above, the present invention further comprises: an insulating member, the insulating member comprising: a first insulating portion disposed between the end cap and the electrode assembly; and

[0013] The second insulating portion is arranged on the first insulating portion, and the second insulating portion extends in the axial direction toward the electrode assembly. The first electrode tab and the second electrode tab are spaced apart to form a first spacing groove, and the second insulating portion is arranged in the first spacing groove.

[0014] In addition to or as an alternative to one or more of the features disclosed above, the single battery further has a circumference around the axial direction;

[0015] A plurality of the second insulating parts are provided, and the plurality of the second insulating parts are arranged in a ring shape along the circumferential direction, and two adjacent second insulating parts are spaced apart to form a second spacing groove between the two adjacent second insulating parts.

[0016] In addition to or as an alternative to one or more features disclosed above, the orthographic projection of the second insulating portion on the reference plane is at least one of a circle, a polygon, or a zigzag shape.

[0017] In addition to or as an alternative to one or more of the features disclosed above, the single battery further has a radial direction intersecting with the axial direction;

[0018] The insulating member further includes: a third insulating portion, provided at an end of the second insulating portion away from the first insulating portion in the axial direction, and the third insulating portion is provided between the first electrode tab and the second electrode tab;

[0019] The maximum dimension of the second insulating portion in the radial direction is L1 mm, and the maximum dimension of the third insulating portion in the radial direction is L2 mm, satisfying the following: L1<L2.

[0020] In addition to or as an alternative to one or more features disclosed above, the dimension of the first electrode tab in the axial direction is H1 mm, and the dimension of the second electrode tab in the axial direction is H2 mm, satisfying: H1<H2.

[0021] In addition to or as an alternative to one or more of the features disclosed above, the present invention further comprises: a first current collecting member;

[0022] The first current collecting member is disposed between the first electrode tab and the end cover, and the first insulating portion is disposed between the first current collecting member and the end cover. The pole is electrically connected to the first electrode tab through the first current collecting member.

[0023] In addition to one or more features disclosed above, or as an alternative, the present invention further includes: a second current collecting member disposed between the end cover and the second electrode tab, and the second electrode tab is electrically connected to the end cover through the second current collecting member.

[0024] 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 cell as described in any one of the above items, wherein the single cell is arranged in the box.

[0025] One of the above technical solutions has the following advantages or beneficial effects: the present invention forms a current loop by forming a pole, a first tab, an electrode body, a second tab and an end cap, and limits the orthographic projection area of the second tab on the reference plane to S2 mm. 2 And the orthographic projection area of the first tab on the reference plane S1mm 2 The ratio is within the range of 0.3 to 1.14, so that the current density of the current flowing through the first tab and the current density flowing through the second tab during operation of the single cell are consistent, that is, the current flow capacity of the first tab and the second tab are ensured to be equivalent, thereby optimizing the electron conduction path in the single cell, and further facilitating the improvement of the power performance of the single cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 is a three-dimensional structural view of a single cell provided according to an embodiment of the present application;

[0028] Figure 2 is an exploded structural view of a single cell provided according to an embodiment of the present application;

[0029] Figure 3 is a partial cross-sectional view of a single cell provided according to an embodiment of the present application;

[0030] Figure 4 is a partial cross-sectional view of a single cell provided according to another embodiment of the present application;

[0031] Figure 5 is a three-dimensional structural view of an insulating member provided according to an embodiment of the present application;

[0032] Figure 6 is a top view of an insulating member provided according to an embodiment of the present application;

[0033] Figure 7 is a three-dimensional structural view of an insulating member provided according to another embodiment of the present application;

[0034] Figure 8 is a cross-sectional view of an insulating member provided according to another embodiment of the present application.

[0035] Description of reference numerals:

[0036] 100. Single cell;

[0037] 110. Housing;

[0038] 120, end cap;

[0039] 130. Electrode assembly; 131. Electrode body; 132. First electrode tab; 133. Second electrode tab; 134. First spacing groove;

[0040] 140, insulating member; 141, first insulating portion; 142, second insulating portion; 143, second spacing groove; 144, third insulating portion;

[0041] 150, pole;

[0042] 160, first current collecting part;

[0043] 170, second current collecting piece;

[0044] 180, riveted parts;

[0045] 190. Seals. DETAILED DESCRIPTION

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] In the examples of this application, refer to Figures 1 to 8 The present application provides a single battery 100 , which has an axial direction Z, a radial direction X intersecting the axial direction Z, a circumferential direction R surrounding the axial direction Z, and a reference plane P perpendicular to the axial direction Z.

[0051] 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.

[0052] The single battery 100 may be a cylindrical battery, a prismatic battery, a soft-pack battery, or a battery of other shapes.

[0053] Specifically, the single cell 100 includes a housing 110 , an end cap 120 , a terminal post 150 and an electrode assembly 130 .

[0054] Specifically, the end cover 120 is arranged at one end of the shell 110 in the axial direction Z; the pole 150 is arranged on the end cover 120, and the pole 150 and the end cover 120 are insulated; the electrode assembly 130 is arranged in the shell 110, and the electrode assembly 130 includes an electrode body 131, a first pole ear 132 and a second pole ear 133, the first pole ear 132 and the second pole ear 133 are both arranged at the end of the electrode body 131 in the axial direction Z close to the end cover 120, the polarity of the first pole ear 132 is opposite to the polarity of the second pole ear 133, the first pole ear 132 is electrically connected to the pole 150, the second pole ear 133 is electrically connected to the end cover 120, and the first pole ear 132 and the second pole ear 133 are spaced apart to prevent the first pole ear 132 and the second pole ear 133 from contacting each other and causing a short circuit.

[0055] 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.

[0056] The end cap 120 can be integrally formed with the housing 110, i.e., the end cap 120 and the housing 110 are an integral structure. The end cap 120 can also be fixedly connected to the housing 110, for example, by welding or other processes to the end of the housing 110 that is away from the electrode assembly 130 in the Z direction. 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 120 is provided separately from the housing 110, and the end cap 120 and the housing 110 are welded and fixed.

[0057] The pole 150 is insulated from the end cap 120 to prevent contact between the pole 150 and the end cap 120 and thereby prevent a short circuit. For example, the pole 150 may be a positive pole, and the end cap 120 and the housing 110 may be negative poles, but the present invention is not limited thereto.

[0058] The first electrode tab 132 can be a positive electrode tab or a negative electrode tab, which is not specifically limited in this application and can be selected according to actual circumstances. For example, in this application, the first electrode tab 132 is a positive electrode tab.

[0059] The above-mentioned single cell 100 also includes an electrolyte and other functional components. The electrolyte can be a conventional electrolyte or a special electrolyte with additives. The electrolyte is used to soak the electrode assembly 130. The electrode assembly 130 is the component where the electrochemical reaction occurs in the single cell 100, and there can be one or more electrode assemblies. The electrode assembly 130 is primarily formed by winding a positive electrode sheet, a separator, and a negative electrode sheet. The portions of the positive and negative electrode sheets containing active material constitute the electrode body 131, the portions of the positive electrode sheet without active material constitute the first electrode tab 132, and the portions of the negative electrode sheet without active material constitute the second electrode tab 133. During the charge and discharge process of the single cell 100, the positive and negative electrode active materials react with the electrolyte, electrically connecting the first electrode tab 132 to the terminal 150, and the second electrode tab 133 to the end cap 120, forming a current circuit, allowing the single cell 100 to function normally.

[0060] In order to ensure that the current density flowing through the first tab 132 is consistent with the current density flowing through the second tab 133, that is, to ensure that the current carrying capacity of the first tab 132 and the second tab 133 is equivalent, the first tab 132 and the second tab 133 are designed accordingly in this application. Specifically, the orthographic projection area of the first tab 132 on the reference plane P is S1 mm 2 The orthographic projection area of the second tab 133 on the reference plane P is S2 mm 2 , satisfying: 0.3≤S2 / S1≤1.14. That is, the orthographic projection area of the second tab 133 on the reference plane P is S2 mm 2 and the orthographic projection area S1 mm of the first tab 132 on the reference plane P 2 The ratio of S2 / S1 can be controlled within the range of 0.3 to 1.14. For example, S2 / S1 can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1 or 1.14, or a range consisting of any two of them. The above specific values of S2 / S1 are given for example only, and any value within the range of 0.3 to 1.14 is within the scope of protection of this application.

[0061] The orthographic projection area of the first tab 132 on the reference plane P is S1 mm 2 The orthographic projection area S2 of the second tab 133 on the reference plane P is 2 After the actual single battery 100 is disassembled, a projection measurement device (such as a digital microscope or an image measuring instrument) can be used to take photos and project them multiple times along the axial direction Z to measure the image area of the first tab 132 and the image area of the second tab 133, thereby obtaining the orthographic projection area S1 mm of the first tab 132 on the reference plane P. 2The orthographic projection area S2 of the second tab 133 on the reference plane P is 2 , but not limited to this.

[0062] It can be understood that the present application forms a current loop by the pole 150, the first pole tab 132, the electrode body 131, the second pole tab 133 and the end cap 120, and by limiting the orthographic projection area S2 mm of the second pole tab 133 on the reference plane P 2 and the orthographic projection area S1 mm of the first tab 132 on the reference plane P 2 The ratio is within the range of 0.3 to 1.14, so that the current density of the current flowing through the first electrode tab 132 and the current density flowing through the second electrode tab 133 during operation of the single cell 100 are consistent, that is, the current flow capacity of the first electrode tab 132 and the second electrode tab 133 are ensured to be equivalent or even the same, thereby optimizing the electron conduction path in the single cell 100 and facilitating improving the power performance of the single cell 100.

[0063] In one embodiment, referring to Figures 2 to 4 The first pole tab 132 and the second pole tab 133 both extend in a direction close to the end cover 120; the first pole tab 132 and the second pole tab 133 are both arranged in a ring shape, and the second pole tab 133 surrounds the outer circumference of the first pole tab 132 to prevent the first pole tab 132 and the second pole tab 133 from contacting each other and causing a short circuit in the single battery 100, thereby improving the safety performance of the single battery 100.

[0064] The electrode body 131 includes a first electrode piece, a diaphragm, and a second electrode piece. The diaphragm is provided between the first electrode piece and the second electrode piece to prevent the first electrode piece and the second electrode piece from contacting and causing a short circuit. The first electrode piece, the diaphragm, and the second electrode piece are stacked and wound in sequence. The annular first electrode tab 132 can be formed by stacking a plurality of first metal sheets connected to the first electrode piece in a radial direction X after the first electrode piece is wound. The annular second electrode tab 133 can be formed by stacking a plurality of second metal sheets connected to the second electrode piece in a radial direction X after the second electrode piece is wound.

[0065] In one embodiment, referring to Figures 2 to 3 The first tab 132 and the second tab 133 are spaced apart to form a first spacing groove 134 . The single cell 100 further includes an insulating member 140 , a portion of which is disposed between the end cap 120 and the electrode assembly 130 , and another portion of which is disposed in the first spacing groove 134 .

[0066] Specifically, the insulating member 140 includes: a first insulating portion 141 and a second insulating portion 142. The first insulating portion 141 is arranged between the end cover 120 and the electrode assembly 130 to insulate and isolate the end cover 120 from the electrode assembly 130, and prevent the two from contacting and causing a short circuit in the single cell 100; the second insulating portion 142 is arranged on the first insulating portion 141, and the second insulating portion 142 extends in the axial direction Z along the direction toward the electrode assembly 130. The second insulating portion 142 is arranged in the first spacing groove 134 to further insulate and isolate the first pole ear 132 from the second pole ear 133, and further prevent the first pole ear 132 and the second pole ear 133 from contacting and causing a short circuit in the single cell 100.

[0067] The first insulating portion 141 and the second insulating portion 142 may be made of various materials. For example, the first insulating portion 141 and the second insulating portion 142 may be made of rubber, silicone, plastic, etc., but are not limited thereto.

[0068] The first insulating portion 141 can be integrally formed with the second insulating portion 142, i.e., the first insulating portion 141 and the second insulating portion 142 are an integral structure. The first insulating portion 141 can also be fixedly connected to the second insulating portion 142, for example, by a process such as snapping or riveting. This is not specifically limited in this application and can be specifically configured according to actual circumstances. For example, in this application, the first insulating portion 141 and the second insulating portion 142 are integrally injection molded.

[0069] In one embodiment, referring to Figures 5 and 6 Multiple second insulating portions 142 are provided, and the plurality of second insulating portions 142 are arranged in a ring along the circumferential direction R. These second insulating portions 142 insulate and isolate the plurality of first tabs 132 and the plurality of second tabs 133, further preventing contact between the first tabs 132 and the second tabs 133 and causing a short circuit in the battery cells 100. Adjacent second insulating portions 142 are spaced apart to form a second spacing groove 143 between the two adjacent second insulating portions 142. This ensures that the first tabs 132 and the second tabs 133 are insulated and isolated, while also preventing deformation of the second insulating portions 142 caused by stress release during injection molding of the insulating member 140, thereby ensuring the molding effect of the insulating member 140 and improving the processing efficiency of the insulating member 140.

[0070] In one embodiment, referring to Figures 5 and 6 The orthographic projection of the second insulating portion 142 on the reference plane P is at least one of a circle, a polygon, or a Z-shape. That is, the orthographic projection of the second insulating portion 142 on the reference plane P can be a circle, a polygon, or a Z-shape. For example, in the present application, the orthographic projections of the plurality of second insulating portions 142 on the reference plane P are all Z-shaped.

[0071] In one embodiment, referring to Figures 7 and 8 The insulating member 140 further includes: a third insulating portion 144 , which is disposed at an end of the second insulating portion 142 away from the first insulating portion 141 in the axial direction Z, and the third insulating portion 144 is disposed between the first electrode tab 132 and the second electrode tab 133 .

[0072] Among them, the third insulating part 144 can be integrally formed with the first insulating part 141 and the second insulating part 142, that is, the first insulating part 141, the second insulating part 142 and the third insulating part 144 are an integrated structure; the third insulating part 144 can also be fixedly connected to the first insulating part 141 and the second insulating part 142 respectively, for example: the third insulating part 144 is fixedly connected to the first insulating part 141 and the second insulating part 142 respectively by a process such as clamping or riveting. This is not specifically limited in this application and can be specifically set according to actual circumstances. For example, in this application, the first insulating part 141, the second insulating part 142 and the third insulating part 144 are integrally injection molded.

[0073] The third insulating portion 144 may be made of various materials. For example, the third insulating portion 144 may be made of rubber, silicone, or plastic, but is not limited thereto.

[0074] Specifically, refer to Figures 7 and 8 The maximum dimension of the second insulating portion 142 in the radial direction (X) is L1 mm, and the maximum dimension of the third insulating portion 144 in the radial direction (X) is L2 mm, satisfying the following relationship: L1 < L2. That is, the maximum dimension (L1 mm) of the second insulating portion 142 in the radial direction (X) is smaller than the maximum dimension (L2 mm) of the third insulating portion 144 in the radial direction (X). This means that the cross-section of the insulating member 140 at the second insulating portion 142 and the third insulating portion 144 is I-shaped. This ensures the overall strength of the insulating member 140, making it less susceptible to deformation, while also reducing the material used during the molding of the insulating member 140 and lowering production costs.

[0075] The maximum dimension L1 mm of the second insulating portion 142 in the radial direction X can be obtained by disassembling the actual single battery 100, measuring the distance between two opposing walls of the second insulating portion 142 of the insulating member 140 in the radial direction X 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 instruments.

[0076] The maximum dimension L2 mm of the third insulating portion 144 in the radial direction X can be obtained by disassembling the actual single battery cell 100, repeatedly measuring the distance between two opposing walls of the third insulating portion 144 of the insulating member 140 in the radial direction X 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 dimension measuring instruments.

[0077] In one embodiment, referring to Figure 3 The dimension of the first electrode tab 132 in the axial direction Z is H1 mm, and the dimension of the second electrode tab 133 in the axial direction Z is H2 mm, satisfying: H1<H2. That is, the dimension H1 mm of the first electrode tab 132 in the axial direction Z is smaller than the dimension H2 mm of the second electrode tab 133 in the axial direction Z.

[0078] The dimension H1 mm of the first tab 132 in the axial direction Z and the dimension H2 mm of the second tab 133 in the axial direction Z can be obtained by disassembling the actual single battery 100, measuring the dimension of the first tab 132 and the dimension of the second tab 133 in the axial 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 instruments.

[0079] In the present application, the dimension H1 mm of the first pole tab 132 in the axial direction Z is controlled to be smaller than the dimension H2 mm of the second pole tab 133 in the axial direction Z, so as to prevent the positive electrode collector plate and the negative electrode collector plate from contacting the end cover 120 at the same time after the single cell 100 is assembled, thereby preventing the battery from short-circuiting, thereby ensuring the normal use of the single cell 100 and facilitating the overall assembly of the single cell 100.

[0080] In one embodiment, referring to Figure 3 The single cell 100 further includes a first current collector 160 . The first current collector 160 is disposed between the first electrode tab 132 and the end cap 120 , and the first insulating portion 141 is disposed between the first current collector 160 and the end cap 120 . The electrode 150 is electrically connected to the first electrode tab 132 via the first current collector 160 . The second electrode tab 133 is electrically connected to the end cap 120 . Exemplarily, the second electrode tab 133 is directly electrically connected to the end cap 120 , thereby reducing the number of components in the single cell 100 and lowering production costs.

[0081] It can be understood that the present application arranges the first pole ear 132 and the second pole ear 133 on the same side, and the first pole ear 132 is electrically connected to the pole column 150 through the first current collector 160, and the second pole ear 133 is electrically connected to the end cover 120, so that the single cell 100 forms a current path of the pole column 150-first current collector 160-first pole ear 132-electrode body 131-second pole ear 133-end cover 120, thereby making the current path of the single cell 100 during normal operation not conductive to the shell 110, thereby making the resistance value of the structural parts of the single cell 100 during operation not include the shell, thereby effectively reducing the internal resistance of the single cell 100 and improving the performance of the single cell 100.

[0082] The pole 150 may be made of, but not limited to, a conductive metal or other material. For example, the pole 150 may be made of, but not limited to, copper or aluminum.

[0083] The first current collecting member 160 may be made of various materials. For example, the first current collecting member 160 may be made of copper, iron, aluminum, steel, or aluminum alloy, but is not limited thereto.

[0084] The connection structures between the first current collecting member 160 and the first electrode tab 132 and between the first current collecting member 160 and the electrode post 150 may be various, for example, welding, abutment, or clamping.

[0085] In one embodiment, referring to Figure 4 The single battery 100 further includes: a second current collector 170, which is disposed between the end cover 120 and the second electrode tab 133, and the second electrode tab 133 can be electrically connected to the end cover 120 through the second current collector 170 to form a current flow path of the second electrode tab 133-the second current collector 170-the end cover 120.

[0086] The second current collecting member 170 may be made of various materials. For example, the second current collecting member 170 may be made of copper, iron, aluminum, steel, or aluminum alloy, but is not limited thereto.

[0087] The connection structures between the second current collecting member 170 and the second electrode tab 133 and between the second current collecting member 170 and the end cover 120 can be various, for example, welding, abutting or clamping.

[0088] 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.

[0089] 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.

[0090] To better understand the technical solution of the present application, a lithium-ion battery is used as an example for further explanation.

[0091] This embodiment provides a method for preparing a lithium-ion battery, and the specific process is as follows:

[0092] 1. Preparation of positive electrode

[0093] 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.

[0094] 2. Preparation of negative electrode sheet

[0095] 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.

[0096] 3. Preparation of electrolyte

[0097] 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.

[0098] 4. Preparation of diaphragm

[0099] PP film is used as the separator.

[0100] 5. Preparation of lithium-ion batteries

[0101] 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.

[0102] 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 Table 1.

[0103] Among them, in Examples 1 to 8 and Comparative Examples 1 to 2 in Table 1, lithium ion batteries were prepared according to the above method, and the differences between Examples 2 to 8 and Comparative Examples 1 to 2 and Example 1 are: changes in the values of S1, S2 and S2 / S1.

[0104] The batteries prepared in the above examples and comparative examples were subjected to performance tests. The specific test items were as follows:

[0105] 1. Test method for heat dissipation performance of lithium-ion batteries:

[0106] At 25°C, the lithium-ion battery was allowed to rest for 30 minutes, then discharged at a constant current rate of 1C. After resting for 10 minutes, the battery was then charged at a constant current and constant voltage rate of 1C. After 10 cycles of charge and discharge, the battery was disassembled and the first temperature T1 at the first tab of the lithium-ion battery was measured. The second temperature T2 at the second tab of the lithium-ion battery was measured, and the temperature difference |T1-T2| between the two was calculated. If the temperature difference between the two is within 0-5°C, the current capacity at the first and second tabs is considered to be equivalent, and the lithium-ion battery meets the requirements. Conversely, if the temperature difference between the two exceeds 5°C, the lithium-ion battery does not meet the requirements.

[0107] Test the maximum temperature rise on the surface of lithium-ion batteries.

[0108] The relevant parameters and test results in the above embodiments and comparative examples are recorded in Table 1.

[0109] Table 1 Parameters and test results of Examples 1 to 8 and Comparative Examples 1 to 2

[0110] <![CDATA[S1 / mm 2 ]]> <![CDATA[S2 / mm 2 ]]> <![CDATA[S2 / S1]]> <![CDATA[T1 / ℃]]> <![CDATA[T2 / ℃]]> <![CDATA[|T1-T2|(℃)]]> Example 1 587 668 1.14 45 40.3 4.7 Example 2 632 614 0.97 43.5 40.7 2.8 Example 3 678 558 0.82 43 41.4 1.6 Example 4 726 475 0.65 42 42 0 Example 5 775 442 0.57 41.7 42.3 0.6 Example 6 827 381 0.46 40.8 43.8 3 Example 7 853 350 0.41 40.2 44.6 4.4 Example 8 938 280 0.30 40.1 45 4.9 Comparative Example 1 256 997 0.26 40 47 7 Comparative Example 2 544 721 1.33 52 40 12

[0111] It can be seen from the data in Table 1 that in Comparative Examples 1 and 2, the specific parameters of the lithium-ion batteries exceeded the parameter range of this application, and the lithium-ion batteries did not show corresponding performance and did not meet the requirements.

[0112] It can be seen that the present application defines the orthographic projection area S2mm of the second tab 133 on the reference plane P. 2 and the orthographic projection area S1 mm of the first tab 132 on the reference plane P 2 The ratio is within the range of 0.3 to 1.14, so that the current density of the current flowing through the first electrode tab 132 and the current density flowing through the second electrode tab 133 during operation of the single cell 100 are consistent, that is, the current flow capacity of the first electrode tab 132 and the second electrode tab 133 are ensured to be equivalent, thereby optimizing the electron conduction path in the single cell 100, which is beneficial to improving the power performance of the single cell 100.

[0113] 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 an axial direction and a reference plane perpendicular to the axial direction, characterized in that: include: case; an end cover, disposed at one end of the housing in the axial direction; A pole, wherein the pole is arranged on the end cover, and the pole and the end cover are insulated; as well as an electrode assembly disposed in the housing, the electrode assembly comprising an electrode body, a first electrode tab, and a second electrode tab, wherein the first electrode tab and the second electrode tab are both disposed at an end of the electrode body in the axial direction close to the end cap, the polarity of the first electrode tab is opposite to the polarity of the second electrode tab, the first electrode tab is electrically connected to the electrode post, the second electrode tab is electrically connected to the end cap, and the first electrode tab and the second electrode tab are spaced apart; The orthographic projection area of the first tab on the reference plane is S1 mm 2 The orthographic projection area of the second tab on the reference plane is S2 mm 2 , satisfying: 0.3≤S2 / S1≤1.

14.

2. The single cell according to claim 1, wherein: The first pole tab and the second pole tab both extend in a direction close to the end cover; the first pole tab and the second pole tab are both arranged in a ring shape, and the second pole tab surrounds the outer circumference of the first pole tab.

3. The single cell according to claim 2, wherein: Also includes: An insulating member, the insulating member comprising: a first insulating portion, disposed between the end cap and the electrode assembly; as well as The second insulating portion is arranged on the first insulating portion, and the second insulating portion extends in the axial direction toward the electrode assembly. The first electrode tab and the second electrode tab are spaced apart to form a first spacing groove, and the second insulating portion is arranged in the first spacing groove.

4. The single cell according to claim 3, wherein: The single cell further has a circumference around the axial direction; A plurality of the second insulating parts are provided, and the plurality of the second insulating parts are arranged in a ring shape along the circumferential direction, and two adjacent second insulating parts are spaced apart to form a second spacing groove between the two adjacent second insulating parts.

5. The single cell according to claim 4, wherein: The orthographic projection of the second insulating portion on the reference plane is at least one of a circle, a polygon, or a Z-shape.

6. The single cell according to claim 3, wherein: The single battery further has a radial direction intersecting with the axial direction; The insulating member further includes: a third insulating portion, provided at an end of the second insulating portion away from the first insulating portion in the axial direction, and the third insulating portion is provided between the first electrode tab and the second electrode tab; The maximum dimension of the second insulating portion in the radial direction is L1 mm, and the maximum dimension of the third insulating portion in the radial direction is L2 mm, satisfying the following: L1<L2.

7. The single cell according to any one of claims 1 to 6, wherein: The dimension of the first electrode tab in the axial direction is H1 mm, and the dimension of the second electrode tab in the axial direction is H2 mm, satisfying: H1<H2.

8. The single cell according to claim 3, wherein: Also includes: a first current collecting member; The first current collecting member is disposed between the first electrode tab and the end cover, and the first insulating portion is disposed between the first current collecting member and the end cover. The pole is electrically connected to the first electrode tab through the first current collecting member.

9. The single cell according to claim 8, wherein: Also includes: The second current collecting member is disposed between the end cover and the second electrode tab, and the second electrode tab is electrically connected to the end cover through the second current collecting member.

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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