Battery cell and power device

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a power device. The battery cell comprises an assembly main body, a pole group and a connecting sheet, the assembling main body is provided with a pole; the pole group is provided with a pole lug; the connecting piece comprises a first connecting part and a second connecting part, the first connecting part is welded with the pole to form a first welding mark, and the second connecting part is welded with the tab to form a second welding mark; the internal resistance R of the connecting sheet meets the following conditions: # imgabs0 #, R is greater than or equal to 0.005 m omega and less than or equal to 0.05 m omega, and rho is the resistivity of the material of the connecting sheet; l is the vertical distance between the center of the first welding mark and the center of the second welding mark in the length direction of the assembly body; w is the width of the second connecting part; t is the thickness of the connecting piece. According to the invention, the internal resistance R of the connecting sheet is controlled within the range of 0.005 mOmega to 0.05 mOmega, so that the internal resistance of the battery cell can be reduced, and the purpose of improving the quick charging capacity of the battery is achieved.

Description

Technical Field

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

[0002] As power batteries are increasingly used in vehicles, users have an increasing demand for fast charging, so how to reduce the internal resistance of the battery cell has become a very important issue.

[0003] Currently, most battery cells still need to be connected between the internal electrode group and the assembly body through adapters to achieve a bidirectional charging and discharging cycle.

[0004] The existing connector design can basically only meet the needs of conventional low-rate batteries. Once the demand for fast charging is increased, the connector is often the biggest bottleneck in the overcurrent capacity of the internal structural parts of the battery cell, resulting in increased heat generation at the connection between the internal assembly body of the battery cell and the pole ear, and higher local temperature rise, which affects the performance of the battery and cannot improve the fast charging capability. Summary of the invention

[0005] In view of this, the present invention provides a battery cell and a power device to solve the problem of how to reduce the contact internal resistance through the structural design of the connecting piece.

[0006] In a first aspect, the present invention provides a battery cell, including an assembly body, an electrode group, and a connecting piece. The assembly body is provided with a pole; the electrode group is provided with a pole ear; the connecting piece includes a first connecting portion and a second connecting portion, the first connecting portion is welded to the pole to form a first weld mark, and the second connecting portion is welded to the pole ear to form a second weld mark; the internal resistance of the connecting piece is R, in mΩ, and satisfies: , 0.005mΩ≤R≤0.05mΩ, Wherein, ρ is the resistivity of the material of the connecting piece, in Ω·m; W is the width of the second connecting portion, in mm; T is the thickness of the connecting piece, in mm; The assembly body includes a cover plate, and L is a vertical distance between the center of the first weld mark and the center of the second weld mark along the length direction of the cover plate, in mm; Or, the assembly body includes a shell, and L is a vertical distance between the center of the first weld mark and the center of the second weld mark along the length direction of the battery core, in mm.

[0007] Beneficial effect: The battery cell provided by the present invention has a pole column arranged on the assembly body, a pole lug arranged on the pole group, and a connecting piece located between the assembly body and the pole group for welding the pole column and the pole lug to achieve electrical conduction. The internal resistance R of the connecting piece can be calculated by the above parameters and calculation formula, and the internal resistance R of the connecting piece can be controlled within the range of 0.005mΩ to 0.05mΩ by changing the parameters of ρ, L, W and T, so as to reduce the internal resistance of the battery cell and achieve the purpose of improving the fast charging capability of the battery.

[0008] In an optional embodiment, 10 mm ≤ L ≤ 60 mm.

[0009] In an optional embodiment, the total length of the assembly body is L 1 , unit is mm, satisfying: 0.2≤L / L 1 ≤0.45,70 mm≤L 1 ≤500mm.

[0010] In an optional implementation, the width W of the second connecting portion satisfies: 16 mm≤W≤75 mm.

[0011] In an optional embodiment, the total width of the assembly body is W 1 , in mm, and also meets the following requirements: 0.5 ≤ W / W 1 ≤0.9,20mm≤W 1 ≤80mm.

[0012] In an optional embodiment, the thickness T of the connecting sheet satisfies: 0.5 mm ≤ T ≤ 3.5 mm.

[0013] In an optional implementation, the material of the connecting piece is copper, and the internal resistance R of the connecting piece satisfies: 0.01 mΩ≤R≤0.03 mΩ.

[0014] In an optional implementation, the material of the connecting piece is aluminum, and the internal resistance R of the connecting piece satisfies: 0.01 mΩ≤R≤0.035 mΩ.

[0015] In an optional embodiment, the second connecting portion is a U-shaped structure, the second connecting portion forms two pole ear connecting portions, each pole ear connecting portion is welded to a corresponding pole ear to form a second weld mark, the pole includes a positive pole and a negative pole, a pole group is provided with two pole ears corresponding to each pole, one pole group is provided, and each pole is connected to the corresponding two pole ears through a connecting plate; or, two pole groups are provided, and each pole is connected to the corresponding four pole ears through two connecting plates.

[0016] In a second aspect, the present invention further provides a power device, comprising a battery cell according to any one of the above technical solutions.

[0017] Beneficial effect: Since the power device includes a battery cell, it has the same effect as the battery cell and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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.

[0019] Figure 1 This is a schematic structural diagram of a connecting piece in a battery cell according to an embodiment of the present invention; Figure 2 for Figure 1 A top view of the connecting piece shown; Figure 3 for Figure 1 A front view of the connecting piece shown; Figure 4 for Figure 1 A schematic diagram of the structure of welding the connecting piece to an assembly body and a tab; Figure 5 It is a schematic structural diagram of a connecting piece in another battery cell according to an embodiment of the present invention; Figure 6 for Figure 5 The schematic diagram of the structure of the connecting piece after assembly shown; Figure 7 for Figure 5 A schematic diagram of the structure of the connection piece shown being welded to another assembly body and a tab; Figure 8 For the general Figure 7 A schematic diagram of the structure after the connecting piece in FIG. is folded; Fig. 9 This is a schematic structural diagram of a battery cell according to an embodiment of the present invention; Fig.10 for Fig. 9 An exploded view of the battery cell shown; Fig.11 FIG. 4 is an exploded view of another battery cell according to an embodiment of the present invention.

[0020] Description of reference numerals: 1. Cover plate; 2. Connecting piece; 21. First connecting part; 22. Second connecting part; 221. Pole ear connecting part; 23. First weld mark; 24. Second weld mark; 3. Pole group; 31. Pole ear; 4. Shell; 5. Pole column. DETAILED DESCRIPTION

[0021] 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.

[0022] Combine the following Figures 1 to 11 , describing an embodiment of the present invention.

[0023] According to an embodiment of the present invention, on the one hand, a battery cell is provided, including an assembly body, an electrode group 3 and a connecting piece 2. The assembly body is provided with a pole 5; the pole group 3 is provided with a pole ear 31; the connecting piece 2 includes a first connecting portion 21 and a second connecting portion 22, the first connecting portion 21 is welded to the pole 5 to form a first weld mark 23, and the second connecting portion 22 is welded to the pole ear 31 to form a second weld mark 24; the internal resistance of the connecting piece 2 is R, in mΩ, which satisfies: , 0.005mΩ≤R≤0.05mΩ, Wherein, ρ is the resistivity of the material of the connecting sheet 2, in units of Ω·m; W is the width of the second connecting portion 22, in units of mm; T is the thickness of the connecting sheet 2, in units of mm; The assembly body includes a cover plate 1, such as Figure 4 As shown, L is the vertical distance between the center of the first weld mark 23 and the center of the second weld mark 24 along the length direction of the cover plate 1, in mm. Fig.10 In the illustrated embodiment, the direction indicated by F is both the length direction of the cover plate 1 and the length direction of the battery cell.

[0024] Or, the assembly body includes a housing 4, and L is the vertical distance between the center of the first weld mark 23 and the center of the second weld mark 24 along the length direction of the battery core, in mm. Fig.10 and Fig.11 In the illustrated embodiment, the direction indicated by F is the length direction of the battery cell. When the assembly body is a shell 4, the pole 5 is provided on the shell 4. Specifically, in some embodiments, the shell 4 includes two first side walls arranged opposite to each other and two second side walls arranged opposite to each other, and the area of ​​the second side wall is smaller than the area of ​​the first side wall, that is, the first side wall is the large surface of the shell 4, and the second side wall is the narrow surface of the shell 4. The pole 5 is provided on the second side wall of the shell 4. At this time, measured along the length direction of the battery cell, L is the vertical distance between the center of the first weld mark 23 and the center of the second weld mark 24.

[0025] The battery cell provided by the embodiment of the present invention, wherein the pole 5 is arranged on the assembly body, the pole lug 31 is arranged on the pole group 3, and the connecting piece 2 is located between the assembly body and the pole group 3, and is used to conductively connect the pole 5 and the pole lug 31. The internal resistance R of the connecting piece 2 can be calculated by the above parameters and calculation formula, and by changing the parameters of ρ, L, W and T, the internal resistance R of the connecting piece 2 can be controlled within the range of 0.005mΩ to 0.05mΩ, which can reduce the internal resistance of the battery cell, thereby reducing the heat generated at the connection between the assembly body and the pole lug 31 inside the battery cell, ensuring that the performance of the battery is not affected, and achieving the purpose of improving the fast charging capability of the battery.

[0026] Specifically, a single pole 5 may be provided on the assembly body, or a plurality of poles 5 may be provided, such as Figure 4 In the illustrated embodiment, the assembly body is provided with two poles 5 , and correspondingly, two connecting pieces 2 are also provided, and the positive and negative poles of the pole group 3 have pole ears 31 on the same side.

[0027] In some embodiments, 10 mm ≤ L ≤ 60 mm.

[0028] In some embodiments, laser welding is used between the connecting piece 2 and the pole 5, and the first weld mark 23 is a laser weld mark.

[0029] In some embodiments, ultrasonic welding is used between the connecting sheet 2 and the tab 31 , and the second weld mark 24 is an ultrasonic weld mark.

[0030] Although the internal resistance R of the connecting piece 2 can be reduced by reducing L, when L is too small, less than 10 mm, the laser welding mark and the ultrasonic welding mark cannot be distributed at the same time. When L is too large, more than 60 mm, the internal resistance R of the connecting piece 2 becomes larger, and the structural layout of the connecting piece 2 on the assembly body is affected. Therefore, it is more reasonable to control L within the range of 10 mm to 60 mm.

[0031] Typically, the first weld mark 23 and the second weld mark 24 are both approximately regular shapes, and the center of the first weld mark 23 is the geometric center of the first weld mark 23 ; similarly, the center of the second weld mark 24 is the geometric center of the second weld mark 24 .

[0032] In some embodiments, the total length of the assembly body is L 1 , unit is mm, satisfying: 0.2≤L / L 1 ≤0.45,70mm≤L 1 ≤500mm.

[0033] Furthermore, by dividing L by the total length L of the assembly body 1 The ratio is controlled within the range of 0.2 to 0.45, and the total length L of the assembly body applicable to the connecting piece 2 in the battery cell provided by the present invention is 1Within the range of 70mm to 500mm, it can be ensured that L is controlled within a reasonable range.

[0034] Specifically, when the assembly body is the cover plate 1, L 1 is the total length of the cover plate 1; when the assembly body is the housing 4, L 1 is the total length of the shell, that is, the total length of the battery cell.

[0035] In some embodiments, the width W of the second connecting portion 22 satisfies: 16 mm≤W≤75 mm.

[0036] The increase in the width W of the second connection portion 22 is beneficial to reducing the internal resistance R of the connection sheet 2. However, when W is too large, exceeding 75 mm, there is a risk of overlap between the second connection portion 22 and the inner wall of the shell 4 of the battery cell, thereby affecting the safety performance of the battery cell. Specifically, when the assembly body is the cover plate 1, W is too large, and there is a risk of overlap between the second connection portion 22 and the inner wall of the shell 4 of the battery cell; when the assembly body is the shell 4, specifically the second side wall of the shell 4, W is too large, and there is a risk of overlap between the second connection portion 22 and the inner wall of the first side wall of the shell 4.

[0037] In some embodiments, the total width of the assembly body is W 1 , in mm, and also meets the following requirements: 0.5 ≤ W / W 1 ≤0.9,20mm≤W 1 ≤80mm.

[0038] Specifically, when the assembly body is the cover plate 1, W 1 is the total width of the cover plate 1; when the assembly body is a shell, the shell has four side walls, W 1 is the width of the side wall. Taking the second side wall of the housing as an example, W 1 is the width of the second side wall, that is, the thickness of the battery cell.

[0039] If the width W of the second connecting portion 22 exceeds the width W of the assembly body 1 , it cannot be assembled and used. Further specification of the width W of the connecting piece 2 and the width W of the assembly body 1 The relationship between the width W of the connecting piece 2 and the width W of the assembly body 1 The ratio is controlled within the range of 0.5 to 0.9, and the width W of the assembly body suitable for the connecting piece 2 is 1 Between 20mm and 80mm.

[0040] In some embodiments, the thickness T of the connecting sheet 2 satisfies: 0.5 mm ≤ T ≤ 3.5 mm.

[0041] If the thickness T of the connecting sheet 2 is too small, exceeding 0.5 mm, the internal resistance R of the connecting sheet 2 will be too large, and the strength of the connecting sheet 2 will be insufficient, which will easily cause deformation and fracture. If the thickness T of the connecting sheet 2 increases, the internal resistance R of the connecting sheet 2 will decrease, but if T is too large, exceeding 3.5 mm, it will affect the internal capacity space of the battery cell, and cause the weight of the connecting sheet 2 to increase, affecting the energy density of the battery cell. Therefore, the thickness T of the connecting sheet 2 is controlled between 0.5 mm and 2.0 mm.

[0042] In some embodiments, the material of the connecting sheet 2 is copper, and the internal resistance R of the connecting sheet 2 satisfies: 0.01 mΩ≤R≤0.03 mΩ.

[0043] The material of the connecting piece 2 needs to match the material of the pole 5 and the pole ear 31. In this embodiment, the material of the connecting piece 2 is copper, and the resistivity of copper is: ρ=1.75×10 -8 Ω·m, at this time, the preferred range of the internal resistance R of the connecting piece 2 is 0.01mΩ to 0.03mΩ. Controlling the internal resistance R of the connecting piece 2 within the preferred range can reduce the overall internal resistance of the battery cell, and is beneficial to the overall structural layout of the assembly body, as well as improving the strength of the assembly body and the performance of the battery cell.

[0044] In some embodiments, the material of the connecting sheet 2 is aluminum, and the internal resistance R of the connecting sheet 2 satisfies: 0.01 mΩ≤R≤0.035 mΩ.

[0045] In this embodiment, the material of the connecting sheet 2 is aluminum, and the resistivity of aluminum is: ρ=2.83×10 -8 Ω·m, at this time, the preferred range of the internal resistance R of the connecting piece 2 is 0.01mΩ to 0.03mΩ. Controlling the internal resistance R of the connecting piece 2 within the preferred range can reduce the overall internal resistance of the battery cell, and is beneficial to the overall structural layout of the assembly body, as well as improving the strength of the assembly body and the performance of the battery cell.

[0046] In some embodiments, the second connection portion 22 is a U-shaped structure, the second connection portion 22 forms two pole ear connection portions 221, each pole ear connection portion 221 is welded with a pole ear 31 to form a second weld mark 24, the pole 5 includes a positive pole and a negative pole, a pole group 3 and each pole 5 are provided with two pole ears 31, and the pole group 3 is provided with one, and each pole 5 is connected to the corresponding two pole ears 31 through a connecting sheet 2, such as Figures 1 to 4 or, two pole groups 3 are provided, each pole 5 is connected to the corresponding four pole ears 31 through two connecting pieces 2, such as Figures 5 to 8 The embodiment shown.

[0047] Specifically, in Fig.10In the cell embodiment shown, the cell is a square shell cell. In this embodiment, the assembly body is the cover plate 1, and the pole 5 is arranged on the cover plate 1. At this time, the vertical distance between the center of any second weld mark 24 and the center of the first weld mark 23 along the length direction of the cover plate 1 is L, and the total width occupied by the two pole ear connecting parts 221 of a connecting sheet 2 along the width direction of the cover plate 1 is W.

[0048] In such Fig.11 In the cell embodiment shown, the cell is a blade cell. In this embodiment, the assembly body is the cover plate 1, and the pole 5 is arranged on the cover plate 1. At this time, the vertical distance between the center of any second weld mark 24 and the center of the first weld mark 23 along the length direction of the cover plate 1 is L, and the total width occupied by the two pole ear connection parts 221 of a connecting piece 2 along the width direction of the cover plate 1 is W.

[0049] Of course, in some embodiments, the assembly body is a shell 4, and the pole 5 is disposed on the shell 4. Specifically, the shell 4 includes two oppositely disposed first side walls and two oppositely disposed second side walls, the area of ​​the second side wall is smaller than the area of ​​the first side wall, and the pole 5 is disposed on the second side wall of the shell 4. At this time, the vertical distance between the center of any second weld mark 24 and the center of the first weld mark 23 along the length direction of the battery cell is L, and the total width occupied by the two tab connection parts 221 of a connecting sheet 2 along the thickness direction of the battery cell is W, that is, on the second side wall of the shell 4, the total width occupied by the two tab connection parts 221 of a connecting sheet 2 along the width direction of the second side wall is W.

[0050] Specifically, in Figure 5 In the embodiment shown: A pole 5 is connected to a pole lug 31 of the same polarity of the pole group 3 through two connecting sheets 2, for example, the positive pole is connected to the positive pole lug of the pole group 3 through two connecting sheets 2, and the first connecting portions 21 of the two connecting sheets 2 are arranged side by side; similarly, the negative pole is connected to the negative pole lug of the pole group 3 through two connecting sheets 2. Figure 5 The two connecting pieces 2 are symmetrically arranged to form a butterfly shape. The first connecting portions 21 of the two connecting pieces 2 are welded to the pole 5. The two connecting pieces 2 have four pole ear connecting portions 221, which are welded to four pole ears 31 respectively, that is, four second weld marks 24 are formed. Figure 8 shown.

[0051] In such Figure 5 After the connecting piece 2 is connected to the pole 5 and the pole ear 31, the second connecting portion 22 is folded and assembled between the assembly body and the pole group 3, as shown in FIG. Figure 8 shown.

[0052] like Figure 4In the illustrated embodiment, two poles 5 are provided on the assembly body, two connecting plates 2 are provided, and four pole tabs 31 are provided correspondingly to the pole group 3, wherein two pole tabs 31 on the positive pole side are welded to one connecting plate 2, and two pole tabs 31 on the negative pole side are welded to another connecting plate 2.

[0053] The following provides examples and comparative examples to specifically illustrate the technical scheme and technical effects of the present invention. Specific results are shown in Tables 1 to 4. The assembly body is a cover plate 1.

[0054] Table 1: The connecting piece 2 is made of aluminum, ρ=2.83×10 -8 Ω·m.

[0055]

[0056] Table 2: Connecting piece 2 is made of aluminum, ρ=2.83×10 -8 Ω·m.

[0057]

[0058] Table 3: Connector 2 is made of copper, ρ=1.75×10 -8 Ω·m.

[0059]

[0060] Table 4: Connector 2 is made of copper, ρ=1.75×10 -8 Ω·m.

[0061]

[0062] According to an embodiment of the present invention, on the other hand, a power device is provided, comprising the battery cell of any one of the above embodiments.

[0063] Since the power device includes a battery cell and has the same effect as the battery cell, it will not be described in detail here.

[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: An assembly body, wherein the assembly body is provided with a pole; A pole group, wherein the pole group is provided with pole ears; A connecting piece, the connecting piece includes a first connecting portion and a second connecting portion, the first connecting portion is welded to the pole to form a first weld mark, and the second connecting portion is welded to the pole ear to form a second weld mark; the internal resistance of the connecting piece is R, in mΩ, satisfying: ， 0.005mΩ≤R≤0.05mΩ, Wherein, ρ is the resistivity of the material of the connecting piece, in units of Ω·m; W is the width of the second connecting portion, in mm; T is the thickness of the connecting sheet, in mm; The assembly body includes a cover plate, and L is a vertical distance between the center of the first weld mark and the center of the second weld mark along the length direction of the cover plate, in mm; Or, the assembly body includes a shell, and L is a vertical distance between a center of the first weld mark and a center of the second weld mark along a length direction of the battery core, in mm.

2. The battery cell according to claim 1, characterized in that: 10mm≤L≤60mm.

3. The battery cell according to claim 2, characterized in that: The total length of the assembly body is L1, expressed in mm, satisfying: 0.2≤L / L1≤0.45, 70 mm≤L1≤500 mm.

4. The battery cell according to any one of claims 1 to 3, characterized in that: The width W of the second connecting portion satisfies: 16 mm ≤ W ≤ 75 mm.

5. The battery cell according to claim 4, characterized in that: The total width of the assembly body is W1, expressed in mm, and also satisfies the following: 0.5≤W / W1≤0.9, 20mm≤W1≤80mm.

6. The battery cell according to any one of claims 1 to 3, characterized in that: The thickness T of the connecting piece satisfies: 0.5 mm ≤ T ≤ 3.5 mm.

7. The battery cell according to any one of claims 1 to 3, characterized in that: The material of the connecting piece is copper, and the internal resistance R of the connecting piece satisfies: 0.01mΩ≤R≤0.03mΩ.

8. The battery cell according to any one of claims 1 to 3, characterized in that: The material of the connecting piece is aluminum, and the internal resistance R of the connecting piece satisfies: 0.01mΩ≤R≤0.035mΩ.

9. The battery cell according to any one of claims 1 to 3, characterized in that: The second connection portion is a U-shaped structure, the second connection portion forms two tab connection portions, and each tab connection portion is welded to a corresponding tab to form the second weld mark; The poles include a positive pole and a negative pole, and one pole group is provided with two pole ears corresponding to each pole. One pole group is provided, and each pole is connected to two corresponding pole ears through one connecting piece; Alternatively, two pole groups are provided, and each pole is connected to corresponding four pole ears through two connecting sheets.

10. A power device, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 9.

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