Battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises a pole group which comprises a pole group body and an inner pole lug, and the inner pole lug extends out from a part of the pole group body along a first direction; the outer tab is connected with one side, far away from the pole group body, of the inner tab, a partial region of the outer tab is lapped on at least a partial region of the surface of the inner tab, the region, lapped with the inner tab, of the outer tab forms a lapping region, the size of the lapping region in the first direction is W, the size of the lapping region in the second direction is L, the second direction is perpendicular to the first direction; the outer tab and the inner tab are welded to form a welding mark in the lap joint area, the size of the welding mark in the first direction is B, the size of the welding mark in the second direction is A, B / W is larger than or equal to 0.55 and smaller than or equal to 0.85, and A / L is larger than or equal to 0.6 and smaller than or equal to 0.9. Therefore, the welding marks can meet the over-current requirement, and the welding problems of insufficient welding and offset welding are avoided, so that the welding quality is improved, and the percent of pass is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to battery cells and battery packs. Background Art

[0002] The soft-pack battery cell is a commonly used battery cell, which mainly includes a pole group, a packaging film and an outer pole ear. The pole group is located in a confined space formed by the packaging film, and an inner pole ear is provided on the pole group. One end of the outer pole ear is connected to the inner pole ear and the other end extends out of the packaging film. Among them, the outer pole ear and the inner pole ear are connected by welding, and the weld mark formed by welding realizes the relative fixation of the outer pole ear and the inner pole ear and the electrical connection of the outer pole ear and the inner pole ear. During the operation of the battery, the weld mark between the outer pole ear and the inner pole ear serves as a current channel, so that the outer pole ear can lead the current inside the battery to the outside of the battery. Therefore, the design of the weld mark between the outer pole ear and the inner pole ear has an important influence on the overall performance of the battery. However, there are no detailed requirements for the matching relationship between the weld mark and the outer pole ear and the inner pole ear in the prior art, and the consistency is poor. In the welding process of the outer pole ear and the inner pole ear, poor welding problems such as cold welding and welding deviation are prone to occur, resulting in a low battery qualification rate. Summary of the invention

[0003] In view of this, the present invention provides a battery cell and a battery pack to solve the problem of poor welding that is prone to occur during the welding process of the outer tab and the inner tab.

[0004] In the first aspect, the present invention provides a battery cell, comprising: a pole group, comprising a pole group body and an inner pole ear, the inner pole ear extending from a portion of the pole group body along a first direction; an outer pole ear connected to a side of the inner pole ear away from the pole group body, a partial area of ​​the outer pole ear overlapping at least a partial area of ​​the surface of the inner pole ear, and an area of ​​the outer pole ear overlapping with the inner pole ear forming an overlapping area, the size of the overlapping area along the first direction is W, and the size of the overlapping area along the second direction is L, wherein the second direction is perpendicular to the first direction; the outer pole ear and the inner pole ear are welded to form a weld mark in the overlapping area, the size of the weld mark along the first direction is B, and the size of the weld mark along the second direction is A, wherein 0.55≤B / W≤0.85, and 0.6≤A / L≤0.9.

[0005] Beneficial effect: By arranging the outer pole ear and the inner pole ear on the pole group to overlap each other, an overlapping area is formed at the overlapping part of the outer pole ear and the inner pole ear, which is convenient for welding the outer pole ear and the inner pole ear. By arranging the weld mark in the overlapping area, the outer pole ear and the inner pole ear are fixedly connected and electrically connected through the weld mark. Furthermore, by limiting the relationship between the dimension B of the weld mark along the first direction and the dimension W of the overlapping area along the first direction to satisfy the relationship of 0.55≤B / W≤0.85, and the relationship between the dimension A of the weld mark along the second direction and the dimension L of the overlapping area along the second direction to satisfy the relationship of 0.6≤A / L≤0.9, it can be ensured that the width and length of the weld mark have a sufficient proportion relative to the size of the overlapping area, thereby ensuring that the weld mark can meet the overcurrent requirements, and it can also avoid the weld mark being too close to the edge of the inner pole ear or the outer pole ear, which increases the difficulty of welding and causes welding problems such as cold welding and biased welding, thereby improving the welding quality and improving the qualified rate of the battery cell.

[0006] In an optional implementation, the dimension B of the weld mark along the first direction has a value range of: 2 mm ≤ B ≤ 8 mm;

[0007] And / or, a dimension W of the overlapping area along the first direction has a value range of: 2.6 mm ≤ W ≤ 14 mm.

[0008] Beneficial effect: By setting the dimension B of the weld mark along the first direction within the range of 2mm to 8mm, it can be ensured that the weld mark can provide sufficient flow area to meet the flow requirements, and can also avoid the occurrence of cold welds during the welding process of the outer and inner tabs, thereby improving the welding quality.

[0009] By setting the dimension W of the overlap area along the first direction within the range of 2.6 mm to 14 mm, it can be ensured that the overlap area can provide sufficient design position for the weld mark formed by welding, thereby ensuring that the weld mark has a sufficient width dimension along the first direction to meet the overcurrent requirement, and can avoid wasting materials, which is beneficial to improving the energy density of the entire battery cell.

[0010] In an optional embodiment, the dimension A of the weld mark along the second direction has a value range of: 15 mm ≤ A ≤ 70 mm;

[0011] And / or, a dimension L of the overlapping area along the second direction has a value range of: 17 mm ≤ L ≤ 80 mm.

[0012] Beneficial effect: By limiting the dimension A of the weld mark along the second direction to be in the range of 15mm to 70mm, it can be ensured that the weld mark has a sufficient length along the second direction, thereby ensuring that the weld mark can provide sufficient flow area to meet the flow requirements, and can avoid the occurrence of cold welds during the welding process of the outer pole ear and the inner pole ear, thereby improving the welding quality.

[0013] By setting the dimension L of the overlap area along the second direction within the range of 17 mm to 80 mm, it can be ensured that the overlap area can provide sufficient design space for the weld mark formed by welding, thereby ensuring that the weld mark has a sufficient length dimension along the second direction to meet the overcurrent requirements, and can avoid wasting materials, which is beneficial to improving the energy density of the entire battery cell.

[0014] In an optional embodiment, along the first direction, the distance between the side of the weld mark away from the pole group body and the side of the overlap area away from the pole group body is C, wherein 0.1 mm≤C≤1 mm;

[0015] And / or, along the first direction, a distance between a side of the weld mark close to the pole group body and a side of the overlap region close to the pole group body is E, wherein 0.5 mm ≤ E ≤ 5 mm.

[0016] Beneficial effect: By setting the distance C between the side of the weld mark away from the pole group body and the side of the overlap area away from the pole group body to be in the range of 0.1mm to 1mm, it is ensured that the weld mark has a suitable margin to the edge of the inner pole ear, which can not only ensure that the outer pole ear and the inner pole ear can be welded smoothly, and ensure that the weld mark has a sufficient size along the first direction, and avoid the weld mark affecting the pole group body, but also avoid material waste and save costs.

[0017] By setting the distance E along the first direction between the side of the weld mark close to the electrode group body and the side of the overlap area close to the electrode group body to be in the range of 0.5mm to 5mm, it is ensured that in the first direction, the weld mark has a suitable margin to the edge of the outer pole ear, which can not only ensure that the outer pole ear and the inner pole ear can be welded smoothly to avoid the problem of cold welding, but also ensure that the weld mark has a sufficient size along the first direction, thereby ensuring that the weld mark can meet the overcurrent requirements.

[0018] In an optional embodiment, a margin between a side edge of the weld mark and a side edge of the overlap region located on the same side along the second direction is F, wherein 1 mm≤F≤5 mm.

[0019] Beneficial effect: By limiting the margin F between the side edge of the weld mark 3 located on the same side of the second direction and the side edge of the overlap area 201 to take a value in the range of 1mm to 5mm, it is ensured that in the second direction, the edge of the weld mark to the overlap area has a suitable margin, which can avoid the occurrence of cold welding between the outer pole ear and the inner pole ear, and ensure that the weld mark has a sufficient length dimension along the second direction, thereby ensuring that the overcurrent requirements are met, and can avoid excessive weight of the battery cell, avoid waste of materials, and save costs.

[0020] In an optional embodiment, along the second direction, the size of the outer pole ear is smaller than the size of the inner pole ear, the margin F between the side of the weld mark and the side of the overlap area on the same side of the second direction is the margin between the side of the weld mark and the side of the outer pole ear, and the margin between the side of the weld mark and the side of the inner pole ear on the same side of the second direction is G, wherein 1mm≤GF≤5mm.

[0021] Beneficial effect: By setting the size of the outer pole ear along the second direction to be smaller than the size of the inner pole ear along the second direction, it is possible to avoid the outer pole ear being too heavy, avoid wasting materials, save production costs, and help improve the energy density of the battery cell; by setting the difference between the margin G between the side edge of the weld mark 3 located on the same side of the second direction and the side edge of the inner pole ear 102 and the margin F between the side edge of the weld mark 3 located on the same side of the second direction and the side edge of the outer pole ear 2 to be between 1mm and 5mm, it is possible to avoid the outer pole ear being too large in size along the second direction and wasting materials, and it is possible to ensure that the weld mark on the outer pole ear has a sufficient size along the second direction, thereby having sufficient current capacity to meet the needs of the battery cell.

[0022] In an optional embodiment, a value range of a margin G between a side edge of the weld mark and a side edge of the inner tab located on the same side of the second direction is: 2 mm ≤ G ≤ 10 mm.

[0023] Beneficial effects: It can ensure the welding quality between the outer pole ear and the inner pole ear and avoid the occurrence of cold welding, and can also ensure that the weld mark has a sufficient size along the second direction to meet the overcurrent requirements, and can avoid wasting materials and reduce production costs.

[0024] In an optional embodiment, the battery cell further includes: a seal, which is arranged on the outer pole ear and is spaced apart from the inner pole ear along the first direction; a packaging film, which covers the outer side of the pole group, and the packaging film extends out from one end of the outer pole ear away from the inner pole ear, and a heat seal is formed on the edge of the packaging film, and the heat seal is pressed on the seal.

[0025] Beneficial effects: The electrode group is encapsulated by providing a packaging film to protect the electrode group. A heat seal is provided on the edge of the packaging film to ensure the airtightness of the accommodation space formed by the packaging film. A sealing member is provided on the surface of the outer electrode ear and the heat seal is pressed on the sealing member to further ensure the sealing of the contact position between the packaging film and the outer electrode ear, thereby improving the reliability and safety of the entire battery cell.

[0026] In an optional implementation, a distance between the sealing member and the inner tab along the first direction is D, wherein 0.1 mm≤D≤0.8 mm.

[0027] Beneficial effect: It can prevent the welding heat during the welding process of the outer pole ear and the inner pole ear from being transferred to the seal and melting the seal, and can also avoid the problem that the heat seal on the packaging film cannot be fully pressed on the seal due to the seal being too far away from the inner pole ear, thereby avoiding leakage, thereby ensuring the sealing of the battery cell and improving safety.

[0028] In a second aspect, the present invention further provides a battery pack, comprising: the above-mentioned battery cell. Since the battery pack comprises the battery cell and has the same effect as the battery cell, it will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A structural diagram of a battery cell according to an embodiment of the present invention;

[0031] Figure 2 It is a schematic diagram of the assembly structure of a pole group, an outer pole ear and a sealing member according to an embodiment of the present invention;

[0032] Figure 3 for Figure 2 The diagram is a partial enlarged schematic diagram of the assembly structure of the pole group, the outer pole ear and the seal.

[0033] Description of reference numerals:

[0034] 1. Pole group; 101. Pole group body; 102. Inner pole ear; 2. Outer pole ear; 201. Overlap area; 3. Welding mark; 4. Seal; 5. Packaging film; 501. Heat seal; 6. Tape. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0036] Combine the following Figures 1 to 3 , describing an embodiment of the present invention.

[0037] According to an embodiment of the present invention, on the one hand, a battery cell is provided, comprising: a pole group 1 and an outer pole ear 2. The pole group 1 comprises a pole group body 101 and an inner pole ear 102, wherein the inner pole ear 102 extends from a portion of the pole group body 101 along a first direction; the outer pole ear 2 is connected to a side of the inner pole ear 102 away from the pole group body 101, and a portion of the outer pole ear 2 overlaps at least a portion of the surface of the inner pole ear 102, and an overlapped region 201 is formed on the outer pole ear 2 and the overlapped region 102, wherein the size of the overlapped region 201 along the first direction is W, and the size of the overlapped region 201 along the second direction is L, wherein the second direction is perpendicular to the first direction; the outer pole ear 2 is welded to the inner pole ear 102 to form a weld mark 3 in the overlapped region 201, wherein the size of the weld mark 3 along the first direction is B, and the size of the weld mark 3 along the second direction is A, wherein 0.55≤B / W≤0.85, and 0.6≤A / L≤0.9.

[0038] The first direction refers to Figures 2 to 3 The arrow in the middle refers to the "first direction"; the second direction refers to Figures 2 to 3 The arrow in the middle points to the “second direction”; the units of B, W, A, and L are all mm.

[0039] It should be noted that the overlapping area 201 refers to the overlapping area between the outer tab 2 and the inner tab 102. Figure 3 In the area shown by the middle shaded area, the weld mark 3 is distributed in the overlap area 201. The weld mark 3 serves as the current flow channel between the outer pole ear 2 and the inner pole ear 102. The size of the weld mark 3 directly affects the current flow capacity of the battery cell. B / W represents the proportion of the width dimension of the weld mark 3 to the width dimension of the overlap area 201 along the first direction. If B / W is less than 0.55, the width dimension of the weld mark 3 is too small relative to the width dimension of the overlap area 201, and the problem of insufficient width dimension of the weld mark 3 is likely to occur, resulting in the weld mark 3 being unable to meet the current flow requirement. The failure of the weld mark area to meet the current flow requirement will seriously affect the performance of the battery cell. If B / W is greater than 0.85, the width dimension of the weld mark 3 is too large relative to the width dimension of the overlap area 201, and the weld mark 3 is too close to the edges on both sides of the overlap area 201 located in the first direction, wherein the edges on both sides of the overlap area 201 located in the first direction are the edges of the inner pole ear 102 or the edges of the outer pole ear 2. Therefore, welding is difficult and cold welding problems are likely to occur.

[0040] It should be noted that A / L represents the ratio of the length dimension of the weld mark 3 to the length dimension of the overlap area 201 along the second direction. If A / L is less than 0.6, the length dimension of the weld mark 3 is too small relative to the length dimension of the overlap area 201, and the problem of insufficient length dimension of the weld mark 3 may easily occur, resulting in the weld mark area being unable to meet the overcurrent requirement, seriously affecting the performance of the battery cell capacity; if A / L is greater than 0.9, the length dimension of the weld mark 3 is too large relative to the length of the overlap area 201, then the weld mark 3 is too close to the edges on both sides of the overlap area 201 in the second direction, that is, the weld mark 3 is too close to the edge of the outer pole ear 2, which makes welding difficult and is prone to problems such as biased welding and cold welding.

[0041] In the battery cell of this embodiment, the outer pole ear 2 is overlapped with the inner pole ear 102 on the pole group 1, so that the overlap area 201 is formed at the overlapped part of the outer pole ear 2 and the inner pole ear 102, so that the outer pole ear 2 and the inner pole ear 102 are welded, and the weld mark 3 is arranged in the overlap area 201, so that the outer pole ear 2 and the inner pole ear 102 are fixedly connected and electrically connected through the weld mark 3. Furthermore, by limiting the dimension B of the weld mark 3 along the first direction and the dimension W of the overlap area 201 along the first direction to satisfy 0.55≤B / The relationship formula W≤0.85 and the relationship formula 0.6≤A / L≤0.9 between the dimension A of the weld mark 3 along the second direction and the dimension L of the overlap area 201 along the second direction can ensure that the width and length of the weld mark 3 have a sufficient proportion relative to the dimension of the overlap area 201, thereby ensuring that the weld mark 3 can meet the overcurrent requirement, and can also avoid the weld mark 3 being too close to the edge of the inner pole ear 102 or the outer pole ear 2, which increases the difficulty of welding and causes welding problems such as cold welding and offset welding, thereby improving the welding quality and the qualified rate of the battery cell.

[0042] It should be noted that the battery cell is a soft-pack battery cell, the electrode group 1 is formed by stacking electrode sheets and diaphragms, and an insulating film is provided on the outermost side of the electrode group 1. Preferably, a plurality of tapes 6 are attached to the sides of the outer side of the electrode group body 101 to fix the electrode group body 101 and ensure the overall stability of the electrode group 1. The electrode group body 101 includes a foil and an active material layer coated on the surface of the foil, and the inner electrode ear 102 extends from a partial section of the side of the foil of the electrode group body 101 extending along the second direction along the first direction.

[0043] The following describes the experimental results of testing cells with different B / W and A / L values ​​to experimentally verify the parameter values ​​of the cell.

[0044] Table 1 Cell verification results for different values ​​of B / W and A / L

[0045]

[0046] It can be seen from Table 1 that for the battery cells of Implementation Cases 1 to Implementation Cases 7, the ratios B / W of the dimension B of the weld mark 3 along the first direction to the dimension W of the overlapping area 201 along the first direction are all within the range of 0.55 to 0.85, which are all within the range defined in the present application. The weld mark is completely within the overlapping area where the inner pole ear and the outer pole ear overlap, and there are no problems of cold welding or biased welding. The overcurrent in the weld mark area meets the requirements, and the temperature of the battery cells after charge and discharge tests is within 50°C, which meets the temperature rise requirements of the battery cells, and the battery cells are qualified. For the battery cells of comparative case 1 and comparative case 2, B / W is less than 0.55, which is not within the scope defined in the present application. In the first direction, the size of the weld mark accounts for too small a proportion of the size of the overlap area, that is, the width of the weld mark accounts for too low a proportion of the width of the overlap area, and the overcurrent in the weld mark area does not meet the requirements. After the charge and discharge tests, the temperature of the battery cells exceeds 50°C, and the temperature rise of the battery cells is too large, which is very dangerous. For the battery cells of comparative case 3 and comparative case 4, B / W is greater than 0.85, which is not within the scope defined in the present application. In the first direction, the size of the weld mark accounts for too large a proportion of the size of the overlap area, that is, the width of the weld mark accounts for too high a proportion of the width of the overlap area, and the weld mark is too close to the edge of the pole ear, resulting in cold welding and biased welding, which does not meet the requirements. For the battery cells of Case 5 and Comparative Case 6, the ratio A / L of the dimension A of the weld mark 3 along the second direction to the dimension L of the overlapping area 201 along the second direction is less than 0.6, which is not within the scope specified in the present application. The length of the weld mark is too small relative to the length of the overlapping area, that is, the ratio of the length of the weld mark to the size of the overlapping area is too low, the overcurrent in the weld mark area does not meet the requirements, the temperature exceeds 50°C, the temperature rise of the battery cell is too large, and it is very dangerous. For the battery cells of Comparative Case 7 and Comparative Case 8, A / L is greater than 0.9, which is not within the scope specified in the present application. The length of the weld mark is too large relative to the length of the overlapping area, that is, the ratio of the length of the weld mark to the size of the overlapping area is too high, the weld mark is too close to the edge of the pole ear, and cold welding and biased welding occur, which does not meet the requirements.

[0047] In summary, by limiting the ratio of the dimension B of the weld mark 3 along the first direction to the dimension W of the overlapping area 201 along the first direction to be in the range of 0.55 to 0.85, and the ratio of the dimension A of the weld mark 3 along the second direction to the dimension L of the overlapping area 201 along the second direction to be in the range of 0.6 to 0.9, it can be ensured that the width and length of the weld mark 3 have a sufficient proportion relative to the size of the overlapping area 201, thereby ensuring that the weld mark 3 can meet the overcurrent requirements, and can avoid welding problems such as cold welding and biased welding, thereby improving the welding quality and improving the qualified rate of the battery cells.

[0048] In one embodiment, the value range of the dimension B of the weld mark 3 along the first direction is: 2mm≤B≤8mm. It should be noted that the dimension B of the weld mark 3 along the first direction is the width of the welding of the inner pole ear 102 and the outer pole ear 2, and the orthographic projection area of ​​the weld mark 3 on the surface of the outer pole ear 2 is equal to the flow area between the outer pole ear 2 and the inner pole ear 102. If B is less than 2mm, the width of the weld mark 3 is too small, and the flow capacity does not meet the requirements of the battery cell. If B is greater than 8mm, the width of the weld mark 3 is too large, and the weld mark 3 is too close to the edge of the inner pole ear 102 or the outer pole ear 2 along the first direction. During the welding process, the positioning of the welding tool is more difficult, and the problem of cold welding is prone to occur. Therefore, by setting the dimension B of the weld mark 3 along the first direction to be in the range of 2mm to 8mm, it can be ensured that the weld mark 3 can provide sufficient flow area to meet the flow requirements, and cold welding can be avoided during the welding process of the outer pole ear 2 and the inner pole ear 102, thereby improving the welding quality.

[0049] In one embodiment, the dimension W of the overlap area 201 along the first direction is in the range of 2.6 mm ≤ W ≤ 14 mm. The dimension W of the overlap area 201 along the first direction is the dimension of the overlap area of ​​the outer pole ear 2 and the inner pole ear 102 along the first direction, which is used to provide a position for the weld mark 3. If W is less than 2.6 mm, the dimension of the area where the outer pole ear 2 overlaps the inner pole ear 102 along the first direction is too small, and it is not possible to provide a sufficient design position for the weld mark 3, so that it is difficult to meet the overcurrent requirement. If W is greater than 14 mm, the dimension of the area where the outer pole ear 2 overlaps the inner pole ear 102 along the first direction is too large, which wastes materials and increases the weight of the outer pole ear 2 and the inner pole ear 102, thereby increasing the weight of the entire battery cell, which is not conducive to improving the energy density of the battery cell. Therefore, by setting the dimension W of the overlap area 201 along the first direction to be in the range of 2.6 mm to 14 mm, it can be ensured that the overlap area 201 can provide sufficient design position for the weld mark 3 formed by welding, thereby ensuring that the weld mark 3 has a sufficient width dimension along the first direction to meet the overcurrent requirement, and can avoid wasting materials, which is beneficial to improving the energy density of the entire battery cell.

[0050] In one embodiment, the value range of the dimension A of the weld mark 3 along the second direction is: 15mm≤A≤70mm. It should be noted that the dimension A of the weld mark 3 along the second direction is the connection length of the welding of the inner pole ear 102 and the outer pole ear 2. If A is less than 15mm, the length of the weld mark 3 along the second reverse direction is too small, and the flow area provided by the weld mark 3 cannot meet the flow requirement of the battery cell. If A is greater than 70mm, the length of the weld mark 3 along the second direction is too long, and the weld mark 3 is too close to the margin of the outer pole ear 2 along the second direction. During the welding process, the welding tool is difficult to position, and problems such as biased welding and cold welding are prone to occur. Therefore, by limiting the dimension A of the weld mark 3 along the second direction to a value within the range of 15mm to 70mm, it can be ensured that the weld mark 3 has a sufficient length along the second direction, thereby ensuring that the weld mark 3 can provide a sufficient flow area to meet the flow requirement, and cold welding can be avoided during the welding process of the outer pole ear 2 and the inner pole ear 102, thereby improving the welding quality.

[0051] In one embodiment, the dimension L of the overlap area 201 along the second direction has a value range of: 17mm≤L≤80mm. It should be noted that the weld mark 3 is set in the overlap area 201. If L is less than 17mm, the dimension of the overlapped portion of the outer pole ear 2 and the inner pole ear 102 along the second direction is too small, and it is not possible to provide sufficient design space for the weld mark 3, so that it is difficult to meet the overcurrent requirement. If L is greater than 80mm, the dimension of the overlapped portion of the outer pole ear 2 and the inner pole ear 102 along the second direction is too large, which wastes materials and increases the weight of the outer pole ear 2 and the inner pole ear 102, thereby increasing the weight of the entire battery cell, which is not conducive to improving the energy density of the battery cell. Therefore, by setting the dimension L of the overlap area 201 along the second direction to be within the range of 17mm to 80mm, it can be ensured that the overlap area 201 can provide sufficient design space for the weld mark 3 formed by welding, thereby ensuring that the weld mark 3 has a sufficient length dimension along the second direction to meet the overcurrent requirement, and can avoid wasting materials, which is conducive to improving the energy density of the entire battery cell.

[0052] Preferably, the size of the outer pole tab 2 along the second direction is smaller than the size of the inner pole tab 102 along the second direction, and the size L of the overlapping area 201 along the second direction is the size of the outer pole tab 2 along the second direction. It can be understood that, as an alternative embodiment, the size of the outer pole tab 2 along the second direction can also be greater than or equal to the size of the inner pole tab 102 along the second direction, and the size L of the overlapping area 201 along the second direction is the size of the inner pole tab 102 along the second direction.

[0053] In one embodiment, along the first direction, the distance between the side of the weld mark 3 away from the electrode group body 101 and the side of the overlap area 201 away from the electrode group body 101 is C, where 0.1mm≤C≤1mm. It should be noted that the side of the overlap area 201 away from the electrode group body 101 coincides with the side of the inner pole ear 102 away from the electrode group body 101, then C represents the margin of the side of the weld mark 3 away from the electrode group body 101 from the side of the inner pole ear 102 away from the electrode group body 101. If C is less than 0.1mm, the margin of the weld mark 3 along the first direction to the edge of the inner pole ear 102 is too small, which is prone to cold welding during the welding process, thereby affecting the current capacity of the weld mark 3, resulting in failure to meet the current requirements. If C If it is greater than 1mm, the margin from the weld mark 3 to the edge of the inner pole ear 102 is too large. When the size of the inner pole ear 102 along the first direction and the size of the overlapping area 201 along the first direction are determined, the weld mark 3 will be too close to the pole group body 101, or even the weld mark 3 will overlap the pole group body 101, causing damage to the pole group body 101. Otherwise, the weld mark 3 will not be able to be distributed. If a weld mark 3 of sufficient width is to be formed on the inner pole ear 102, it is necessary to increase the size of the inner pole ear 102 along the first direction, resulting in material waste and increased cost. Therefore, by setting the distance C between the side of the weld mark 3 away from the pole group body 101 and the side of the overlap area 201 away from the pole group body 101 to be in the range of 0.1mm to 1mm, it is ensured that there is a suitable margin from the weld mark 3 to the edge of the inner pole ear 102, which can not only ensure that the outer pole ear 2 and the inner pole ear 102 can be welded smoothly, and ensure that the weld mark 3 has a sufficient size along the first direction, and avoid the weld mark 3 affecting the pole group body 101, but also avoid material waste and save costs.

[0054] In one embodiment, along the first direction, the distance between the side of the weld mark 3 close to the electrode group body 101 and the side of the overlap area 201 close to the electrode group body 101 is E, wherein 0.5 mm≤E≤5 mm. It should be noted that the side of the overlapping area 201 close to the pole group body 101 is the side of the outer pole ear 2 close to the pole group body 101, then E is the margin of the weld mark 3 along the first direction to the side of the outer pole ear 2 close to the pole group body 101, if E is less than 0.5mm, the margin of the weld mark 3 along the first direction to the edge of the outer pole ear 2 is too small, and it is easy to produce a cold weld problem here during the welding process, thereby affecting the current carrying capacity of the weld mark 3, resulting in failure to meet the current carrying requirements, if E is greater than 5mm, the margin of the weld mark 3 along the first direction to the edge of the outer pole ear 2 is too large, then the weld mark 3 is too close to the side of the overlapping area 201 away from the pole group body 101, then the weld mark 3 cannot be distributed, or the weld mark 3 exceeds the side of the overlapping area 201 away from the pole group body 101, then the actual weld mark width between the inner pole ear 102 and the outer pole ear 2 is insufficient, resulting in a reduction in the area of ​​the weld mark 3, affecting the current carrying. Therefore, by setting the distance E along the first direction between the side of the weld mark 3 close to the pole group body 101 and the side of the overlap area 201 close to the pole group body 101 to be in the range of 0.5mm to 5mm, it is ensured that in the first direction, there is a suitable margin from the weld mark 3 to the edge of the outer pole ear 2, which can ensure that the outer pole ear 2 and the inner pole ear 102 can be welded smoothly to avoid the problem of cold welding, and can also ensure that the weld mark 3 has a sufficient size along the first direction, thereby ensuring that the weld mark 3 can meet the overcurrent requirements.

[0055] In one embodiment, the margin between the side edge of the weld mark 3 and the side edge of the overlap area 201 located on the same side of the second direction is F, where 1mm≤F≤5mm. It should be noted that the margin between the side edge of the weld mark 3 and the side edge of the overlap area 201 located on the same side of the second direction refers to the distance between one side edge of the weld mark 3 and one side edge of the overlap area 201 adjacent to the side edge of the weld mark 3, and there is a margin between the side edge of the weld mark 3 and the side edge of the overlap area 201 on both sides of the second direction. If F is less than 1 mm, the margin between the weld mark 3 and the overlap area 201 is too small, and the distance between the side edge of the weld mark 3 on the same side of the second direction and the side edge of the overlap area 201 is too close. In the welding process of the outer pole ear 2 and the inner pole ear 102, a cold weld is likely to occur at the edge position along the second direction on the weld mark 3, resulting in a cold weld between the inner and outer pole ears, affecting the current carrying capacity; if F is greater than 5 mm, the margin between the weld mark 3 and the overlap area 201 is too large, and the distance between the side edge of the weld mark 3 on the same side of the second direction and the side edge of the overlap area 201 is too far, resulting in the length dimension of the weld mark 3 along the second direction being too small and unable to meet the current carrying requirement. If the length requirement of the weld mark 3 along the second direction is to be met, it is necessary to increase the dimension of the overlap area 201 along the second direction, that is, to increase the dimension of the outer pole ear 2 and / or the inner pole ear 102 along the second direction, thereby increasing the weight of the entire battery cell and wasting redundant materials. Therefore, by limiting the margin F between the side edge of the weld mark 3 and the side edge of the overlap area 201 located on the same side of the second direction to take a value in the range of 1mm to 5mm, it is ensured that in the second direction, the weld mark 3 has a suitable margin to the edge of the overlap area 201, which can avoid the occurrence of cold solder joints between the outer pole ear 2 and the inner pole ear 102, and can ensure that the weld mark 3 has a sufficient length dimension along the second direction, thereby ensuring that the overcurrent requirements are met, and can avoid excessive weight of the battery cell, avoid waste of materials, and save costs.

[0056] In one embodiment, along the second direction, the size of the outer pole ear 2 is smaller than the size of the inner pole ear 102, the margin F between the side edge of the weld mark 3 and the side edge of the overlapping area 201 on the same side of the second direction is the margin between the side edge of the weld mark 3 and the side edge of the outer pole ear 2, and the margin between the side edge of the weld mark 3 and the side edge of the inner pole ear 102 on the same side of the second direction is G, wherein 1mm≤GF≤5mm. Since the size of the inner pole ear 102 on the pole group 1 is generally within a fixed range, if the size of the outer pole ear 2 along the second direction is greater than or equal to the size of the inner pole ear 102 along the second direction, the weight of the outer pole ear 2 will increase, wasting materials. Therefore, by setting the size of the outer pole ear 2 along the second direction to be smaller than the size of the inner pole ear 102 along the second direction, it is possible to avoid excessive weight of the outer pole ear 2, avoid waste of materials, save production costs, and help improve the energy density of the battery cell; GF represents the margin between the inner pole ear 102 and the outer pole ear 2 along the second direction. If GF is less than 1 mm, the margin between the inner pole ear 102 and the outer pole ear 2 along the second direction is too small, and the size of the outer pole ear 2 along the second direction is relatively large, wasting materials. If If GF is greater than 5mm, the margin between the inner pole ear 102 and the outer pole ear 2 along the second direction is too large, and the size of the outer pole ear 2 along the second direction is too small, resulting in the length of the weld mark 3 along the second direction being too small, which makes it difficult to meet the overcurrent requirement. Therefore, by setting the difference between the margin G between the side edge of the weld mark 3 located on the same side of the second direction and the side edge of the inner pole ear 102 and the margin F between the side edge of the weld mark 3 located on the same side of the second direction and the side edge of the outer pole ear 2 to be between 1mm and 5mm, it can avoid the waste of materials due to the excessive size of the outer pole ear 2 along the second direction, and ensure that the weld mark 3 on the outer pole ear 2 can have a sufficient size along the second direction, thereby having sufficient overcurrent capacity to meet the needs of the battery cell.

[0057] Preferably, the outer pole ear 2 is centered on the inner pole ear 102 along the second direction, that is, the outer pole ear 2 and the inner pole ear 102 are symmetrically arranged in the center along the second direction as a whole. Then, along the second direction, the margins between the two sides of the outer pole ear 2 and the inner pole ear 102 are equal, which facilitates the positioning of the outer pole ear 2 and the inner pole ear 102 and is beneficial to the uniformity of the current distribution on the inner and outer pole ears.

[0058] In one embodiment, the margin G between the side of the weld mark 3 and the side of the inner pole ear 102 on the same side of the second direction has a value range of: 2mm≤G≤10mm. If G is less than 2mm, the distance between the edge of the weld mark 3 and the edge of the inner pole ear 102 along the second direction is too close, and the variable distance between the weld mark 3 and the outer pole ear 2 is too small, which will cause a cold weld between the inner pole ear 102 and the outer pole ear 2. If G is greater than 10mm, the distance between the edge of the weld mark 3 and the edge of the inner pole ear 102 along the second direction is too far, and the variable distance between the weld mark 3 and the outer pole ear 2 is too large, resulting in the length dimension of the weld mark 3 along the second direction cannot meet the overcurrent requirement. If the length requirement of the weld mark 3 along the second direction is to be guaranteed, it is necessary to increase the dimensions of the outer pole ear 2 and the inner pole ear 102 along the second direction at the same time, resulting in redundant material waste. Therefore, by setting the margin G between the side of the weld mark 3 located on the same side of the second direction and the side of the inner pole ear 102 to a value between 2mm and 10mm, it is possible to ensure the welding quality between the outer pole ear 2 and the inner pole ear 102 and avoid cold solder joints, and to ensure that the weld mark 3 has a sufficient size along the second direction to meet the overcurrent requirements, avoid wasting materials, and reduce production costs.

[0059] In one embodiment, the battery cell further includes: a seal 4 and a packaging film 5. The seal 4 is arranged on the outer pole ear 2, and the seal 4 and the inner pole ear 102 are arranged at intervals along the first direction; the packaging film 5 is coated on the outer side of the pole group 1, and the end of the outer pole ear 2 away from the inner pole ear 102 extends out of the packaging film 5, and a heat seal 501 is formed on the edge of the packaging film 5, and the heat seal 501 is pressed on the seal 4. The pole group 1 is packaged by arranging the packaging film 5 to protect the pole group 1, and the heat seal 501 is arranged on the edge of the packaging film 5 to ensure the airtightness of the accommodation space formed by the packaging film 5, and the sealing member 4 is arranged on the surface of the outer pole ear 2 and the heat seal 501 is pressed on the seal 4, so as to further ensure the sealing of the contact position between the packaging film 5 and the outer pole ear 2, thereby improving the reliability and safety of the entire battery cell.

[0060] Preferably, the sealing member 4 is a sealant, which is easy to use and has good sealing performance.

[0061] In one embodiment, the distance between the seal 4 and the inner pole ear 102 along the first direction is D, wherein 0.1 mm ≤ D ≤ 0.8 mm. It should be noted that D is the distance from the edge of the inner pole ear 102 on the side away from the pole group body 101 to the seal 4. If D is less than 0.1 mm, the distance between the seal 4 and the inner pole ear 102 is too small, which will cause the welding heat during the welding process between the outer pole ear 2 and the inner pole ear 102 to be transferred to the seal 4, causing the seal 4 to melt, affecting the subsequent heat-sealing edge of the packaging film 5. If D is greater than 0.8 mm, the distance between the seal 4 and the inner pole ear 102 is too large. Since the size of the packaging film 5 is certain, it will appear that in the subsequent heat-sealing edge of the packaging film 5, the heat-sealing seal 501 cannot be fully pressed on the seal 4, and there is a risk of leaking. Therefore, by limiting the distance D between the seal 4 and the inner pole ear 102 along the first direction to a value within the range of 0.1 mm to 0.8 mm, it is possible to avoid the welding heat during the welding process between the outer pole ear 2 and the inner pole ear 102 being transferred to the seal 4 and melting the seal 4, and it is also possible to avoid the problem that the heat seal 501 on the packaging film 5 cannot be fully pressed on the seal 4 due to the seal 4 being too far away from the inner pole ear 102, thereby avoiding leakage, thereby ensuring the sealing of the battery cell and improving safety.

[0062] The battery cell of this embodiment, by limiting the matching relationship between the inner pole ear 102 and the outer pole ear 2, ensures the welding quality between the outer pole ear 2 and the inner pole ear 102, improves the welding yield, and thus improves the production qualification rate of the battery cell. It should be noted that the pole group 1 has two inner pole ears 102, one of which is a positive pole ear and the other is a negative pole ear, the two inner pole ears 102 are arranged at intervals, the number of the outer pole ears 2 is two and corresponds to the two inner pole ears 102 one by one, and the matching of the two groups of inner pole ears 102 and the outer pole ears 2 is applicable to the matching relationship between the inner pole ears 102 and the outer pole ears 2 defined in this embodiment.

[0063] According to an embodiment of the present invention, on the other hand, a battery pack is provided, including: the above-mentioned battery cell.

[0064] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that: include: A pole group, comprising a pole group body and an inner pole ear, wherein the inner pole ear extends from a portion of the pole group body along a first direction; An outer pole ear connected to a side of the inner pole ear away from the pole group body, a part of the outer pole ear overlaps at least a part of the surface of the inner pole ear, and the area of ​​the outer pole ear overlapping with the inner pole ear forms an overlapping area, the size of the overlapping area along the first direction is W, and the size of the overlapping area along the second direction is L, wherein the second direction is perpendicular to the first direction; The outer pole ear and the inner pole ear are welded to form a weld mark in the overlap area, the size of the weld mark along the first direction is B, the size of the weld mark along the second direction is A, wherein 0.55≤B / W≤0.85, and 0.6≤A / L≤0.

9.

2. The battery cell according to claim 1, characterized in that: The value range of the dimension B of the weld mark along the first direction is: 2mm≤B≤8mm; And / or, a dimension W of the overlapping area along the first direction has a value range of: 2.6 mm ≤ W ≤ 14 mm.

3. The battery cell according to claim 1, characterized in that: The value range of the dimension A of the weld mark along the second direction is: 15mm≤A≤70mm; And / or, a dimension L of the overlapping area along the second direction has a value range of: 17 mm ≤ L ≤ 80 mm.

4. The battery cell according to claim 1, characterized in that: Along the first direction, the distance between the side of the weld mark away from the electrode group body and the side of the overlap area away from the electrode group body is C, where 0.1 mm ≤ C ≤ 1 mm; And / or, along the first direction, a distance between a side of the weld mark close to the pole group body and a side of the overlap region close to the pole group body is E, wherein 0.5 mm ≤ E ≤ 5 mm.

5. The battery cell according to claim 1, characterized in that: The margin between the side edge of the weld mark and the side edge of the overlap area on the same side of the second direction is F, wherein 1 mm≤F≤5 mm.

6. The battery cell according to claim 5, characterized in that: Along the second direction, the size of the outer pole ear is smaller than that of the inner pole ear, the margin F between the side of the weld mark and the side of the overlap area on the same side of the second direction is the margin between the side of the weld mark and the side of the outer pole ear, and the margin G between the side of the weld mark and the side of the inner pole ear on the same side of the second direction, wherein 1mm≤GF≤5mm.

7. The battery cell according to claim 6, characterized in that: The value range of the margin G between the side edge of the weld mark and the side edge of the inner tab located on the same side of the second direction is: 2mm≤G≤10mm.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The battery cell also includes: A sealing member, wherein the sealing member is disposed on the outer pole lug, and the sealing member and the inner pole lug are spaced apart along the first direction; A packaging film is coated on the outer side of the electrode group, and one end of the outer electrode ear away from the inner electrode ear extends out of the packaging film. A heat seal is formed on the edge of the packaging film, and the heat seal is pressed on the sealing member.

9. The battery cell according to claim 8, characterized in that: The distance between the sealing member and the inner tab along the first direction is D, wherein 0.1 mm≤D≤0.8 mm.

10. A battery pack, characterized in that: include: The battery cell according to any one of claims 1 to 9.

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