Battery Cells and Battery Packs

Abstract

The present invention relates to the field of battery technology, and discloses a battery cell and a battery pack. The battery cell includes: a shell, a cover plate assembly, a pole group and a connecting piece. The connecting piece is bent, which can improve the structural strength of the connecting piece. The first connecting area is opposite to the second connecting area, which is convenient for welding the connecting piece with the pole ear and the pole column respectively. The pole ear passes through the first connecting area from the lower side of the first connecting area upward and then bends toward the upper surface of the first connecting area. The pole ear and the first connecting area are mutually limited in the upper and lower directions to ensure relative stability, improve welding quality, and reduce the total thickness of the pole ear and the first connecting area after assembly. At the same time, by limiting b+0.2mm≤F≤R, while ensuring that the pole ear will not interfere with the second connecting area, the total size of the connecting piece in the upper and lower directions is reduced as much as possible, so as to improve the internal space utilization of the battery cell as much as possible while realizing that the second connecting area will not crush the pole ear and will not overlap and short-circuit with the pole ear.

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] As batteries are widely used in electric vehicles and energy storage, customers have increasing requirements for battery safety performance. Battery cells are the core components of battery pack safety and assembly, and the structural design of battery cells is crucial to battery safety. Battery cells usually include a shell, a cover assembly, and a pole group located inside the shell, and the pole lugs on the pole group are electrically connected to the pole posts on the cover assembly. In the prior art, a connecting piece is usually arranged between the cover assembly and the pole group, and the connecting piece is respectively welded to the pole posts in the cover assembly and the pole lugs on the pole group, thereby achieving electrical connection between the cover assembly and the pole group.

[0003] However, the battery cell in the prior art usually bends the pole ear first and then welds the upper surface of the pole ear to the lower surface of the connecting plate. The bent pole ear itself has a certain size along the height direction of the battery cell. Moreover, since the pole ear, the connecting plate and the pole are connected in sequence along the height direction of the battery cell, more space inside the battery cell will be occupied, resulting in low utilization of the internal space of the battery cell, which is not conducive to improving the overall energy density of the battery cell and seriously affects the overall performance of the battery cell. Summary of the invention

[0004] In view of this, the present invention provides a battery cell and a battery pack to solve the problem of low internal space utilization of the battery cell.

[0005] In a first aspect, the present invention provides a battery cell, comprising: a shell having an open end; a cover plate assembly, arranged at the open end of the shell to close the shell, the cover plate assembly comprising a cover plate and a pole arranged on the cover plate; a pole group, arranged inside the shell, a pole ear being arranged on the side of the pole group facing the cover plate assembly; a connecting piece, located between the cover plate assembly and the pole group, the connecting piece comprising a first connecting area, a second connecting area and a connecting section, the connecting section being fixedly connected between the first connecting area and the second connecting area, the connecting section comprising a bending portion, the bending portion being bent in an arc shape, so as to The first connection area and the second connection area are arranged opposite to each other, the pole lug passes through the first connection area from the lower side of the first connection area upward and then bends toward the upper surface of the first connection area, the pole lug is welded to the upper surface of the first connection area, and the upper surface of the second connection area is welded to the lower surface of the pole; the distance between the upper surface of the first connection area and the lower surface of the second connection area is F, the size of the part of the pole lug located on the upper side of the first connection area along the up and down direction is b, the inner circle radius of the circular ring where the arc-shaped bending portion is located is R, wherein b+0.2mm≤F≤R.

[0006] Beneficial effect: By setting the first connection area of ​​the connecting piece to be welded to the pole ear and the second connection area to be welded to the pole column, the electrical connection between the pole group and the pole column is achieved, and by setting the connecting section on the connecting piece to include a bent portion that is bent in an arc shape, so that the first connection area and the second connection area are opposite to each other, and the connecting piece is bent as a whole, which is convenient for welding the connecting piece to the pole ear and the pole column respectively on the one hand, and can improve the structural strength of the connecting piece on the other hand, by setting the pole ear to pass through the first connection area from the lower side of the first connection area upward and then bend toward the upper surface of the first connection area, so that the bent pole ear part is in contact with the upper surface of the first connection area, then the pole ear and the first connection area are limited to each other in the upper and lower directions, which is convenient for mutual contact in the subsequent welding process. For stability, it is beneficial to improve welding quality, and can reduce the total thickness dimension along the up-down direction after the pole ear and the first connection area are assembled. At the same time, by limiting the distance F between the upper surface of the first connection area and the lower surface of the second connection area and the dimension b of the portion of the pole ear located on the upper side of the first connection area along the up-down direction, and the inner circle radius R of the circular ring where the arc-shaped bending portion is located to satisfy b+0.2mm≤F≤R, while ensuring that the pole ear will not interfere with the second connection area, the total dimension of the connecting piece along the up-down direction is reduced as much as possible, so that the second connection area will not crush the pole ear and will not overlap and short-circuit with the pole ear, while at the same time, the internal space utilization rate of the battery cell is improved as much as possible, which is beneficial to improving the battery cell capacity and energy density.

[0007] In an optional implementation, the inner radius R of the circular ring where the arc-shaped bending portion is located and the main body thickness H1 of the connecting piece satisfy the following relationship: 1.5×H1≤R≤2×H1.

[0008] Beneficial effect: It can ensure that the connecting piece is smoothly formed and the overall yield rate is high during the production process, and it can also avoid that the connecting piece occupies too much space in the up and down directions, thereby improving the internal space utilization of the battery cell.

[0009] In an optional implementation, the main body thickness H1 of the connecting piece ranges from 0.6 mm to 1 mm.

[0010] Beneficial effects: It can ensure that the connecting piece has sufficient strength, ensure the stability of the state of the connecting piece after bending, avoid deformation or breakage, and avoid the difficulty of the bending process due to excessive thickness and strength of the connecting piece, thereby ensuring that the connecting piece can be bent smoothly, improving processing efficiency, and avoiding excessive weight of the connecting piece, thereby reducing costs and improving the energy density of the battery cell.

[0011] In an optional embodiment, the connecting section also includes: a first main body connected between the first connecting area and the bending portion, and a second main body connected between the bending portion and the second connecting area, the first main body and the first connecting area are on the same plane, the second main body is higher than the second connecting area or flush with the second connecting area, and the distance between the upper surface of the second main body and the upper surface of the second connecting area in the up-down direction is H0; the pole includes a column and a base plate, the column is passed through a pole hole opened on the cover plate, the base plate is located on the lower side of the cover plate, the size of the base plate in the up-down direction is K, and the distance between the upper surface of the base plate and the lower surface of the cover plate is N, wherein (K+N)-H0≥N.

[0012] Beneficial effect: The distance H0 along the up-down direction between the upper surface of the second main body and the upper surface of the second connection area, the dimension K of the bottom plate along the up-down direction, and the distance N between the upper surface of the bottom plate and the lower surface of the cover plate are associated with each other, and the dimensions of each component are designed according to the actual space inside the battery cell. While making full use of the internal space of the battery cell, it is ensured that the bending position of the connecting piece does not interfere with the lower plastic part, avoiding deformation caused by mutual squeezing of the lower plastic part and the connecting piece, thereby ensuring the quality of the battery cell.

[0013] In an optional embodiment, the dimension K of the base plate in the up and down directions has a value range of 1.5 mm ≤ K ≤ 2.5 mm; and / or the distance N between the upper surface of the base plate and the lower surface of the cover plate has a value range of 0.6 mm ≤ N ≤ 1 mm.

[0014] Beneficial effect: By setting the dimension K of the bottom plate in the range of 1.5mm to 2.5mm in the vertical direction, it is possible to ensure that the pole has sufficient structural strength and the quality of the battery cell, and to reduce the weight and cost of the pole as much as possible, which is conducive to improving the energy density of the battery cell. By setting the distance N between the upper surface of the bottom plate and the lower surface of the cover plate in the range of 0.6mm to 1mm, it is possible to avoid the bottom plate of the pole from crushing the sealing ring or the lower plastic part, thereby ensuring the insulation between the pole and the cover plate, and to ensure that the pole can fully compress the sealing ring to ensure the sealing between the pole and the cover plate.

[0015] In an optional embodiment, N through holes are provided on the bending portion, and along the width direction of the connecting section, the distance between the two farthest sides on the bending portion is L, and the sum of the dimensions of the N through holes along the width direction of the connecting section is W, wherein L and W satisfy the relationship: 0.3≤W / L≤0.7, and N is a positive integer greater than or equal to 1.

[0016] Beneficial effect: By constructing a bending portion on the connecting section between the first connecting area and the second connecting area, and opening a through hole on the bending portion, the solid part of the bending portion along the width direction is reduced, so that the bending strength of the part is reduced to a certain extent, thereby facilitating the bending of the connecting piece from the bending portion, reducing the processing difficulty, and improving production efficiency. In addition, by limiting the ratio of the size W of the through hole along the width direction to the size L of the bending portion along the width direction to be within the range of 0.3 to 0.7, it can be avoided that the strength of the bending portion is not significantly reduced due to the through hole being too small relative to the size of the bending portion, and the strength of the bending portion is too low due to the through hole being too large relative to the size of the bending portion. It can also be avoided that the connecting piece can be bent smoothly, and the stability of the shape of the connecting piece after bending can be ensured, and the quality of the connecting piece can be ensured, which is conducive to mass production.

[0017] In an optional embodiment, a dimension L of the bending portion along the width direction of the connecting section has a value range of 40 mm to 50 mm; and / or a dimension W of the through hole along the width direction of the connecting section has a value range of 15 mm to 35 mm.

[0018] Beneficial effects: By setting the dimension L of the bending portion along the width direction of the connecting section to be within the range of 40mm-50mm, it can be ensured that the connecting piece can be smoothly bent from the bending portion to improve the processing efficiency, and it can also be ensured that the bending connecting piece still has sufficient strength, and the stability of the bending state of the connecting piece is ensured, thereby improving the quality and reliability of the connecting piece. By setting the dimension W of the through hole along the width direction of the bending portion to be within the range of 15mm-35mm, it can not only weaken the anti-bending strength of the connecting section to a certain extent, improve the processing efficiency of the bending process of the connecting piece, but also avoid the strength of the connecting piece at the bending portion being too low, thereby ensuring the stability and reliability of the connecting piece.

[0019] In an optional embodiment, the main body width of the connecting section is L0, and the main body width L0 of the connecting section and the dimension L of the bending portion along the width direction of the connecting section satisfy the relationship: 0≤(L0-L) / L0<0.2; and / or, the first connection area includes one or more welding parts, each of the welding parts is suitable for welding with at least one pole ear; and / or, the battery cell also includes: an insulating plate, the insulating plate is located between the pole group and the connecting piece, and a through groove is opened on the insulating plate, and the pole ear is welded to the connecting piece after passing through the through groove.

[0020] Beneficial effect: The dimensional relationship between the bending portion and the body of the connecting section is limited to 0≤(L0-L) / L0<0.2, which can effectively prevent the bending portion from extending out of the width range of the body of the connecting section in the width direction due to being squeezed during the bending process, thereby further improving safety. A connecting piece can realize electrical connection with one or more pole groups at the same time, that is, multiple pole groups can be connected to the same integral connecting piece, optimizing the traditional multiple connecting pieces into one, reducing the number of parts, simplifying the process, and achieving cost reduction. By arranging an insulating plate between the pole group and the cover plate, and opening a through groove on the insulating plate, the pole ear can be better protected by passing through the through groove on the insulating plate after being folded, and reducing the risk of poor folding and tearing of the pole ear; and the insulating plate is a whole plate, and the cover plate assembly is directly pressed on the insulating plate. The pressure applied by the insulating plate to the pole group is more uniform, which can better fix the pole group and reduce the risk of the pole piece being crushed.

[0021] In an optional embodiment, the dimension H2 of the insulating plate along the up and down direction has a value range of 0.5mm-1mm; and / or the cover plate assembly also includes a lower plastic part, which is supported between the cover plate and the insulating plate, and the dimension H3 of the lower plastic part along the up and down direction has a value range of 2mm-4mm.

[0022] Beneficial effect: By setting the thickness H2 of the insulating plate within the range of 0.5mm-1mm, it is possible to ensure that the insulating plate has sufficient strength, ensure the stability of the insulating plate structure, avoid damage to the pole group, and avoid excessive weight of the insulating plate, thereby reducing costs. By setting the height of the lower plastic part within the range of 2mm-4mm, it is possible to ensure that there is a reasonable space between the cover plate and the pole group to avoid the pole group from being crushed, and ensure that the cover plate assembly fixes the pole group, thereby ensuring the quality of the battery cell.

[0023] 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

[0024] 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.

[0025] Figure 1 is an exploded schematic diagram of a battery cell according to an embodiment of the present invention;

[0026] Figure 2 for Figure 1A schematic diagram of the structure of the assembled electrode group, insulating plate and connecting piece in the battery cell shown;

[0027] Figure 3 for Figure 1 A top view of the battery cell after assembly is shown;

[0028] Figure 4 for Figure 3 Sectional view in the AA direction;

[0029] Figure 5 for Figure 4 A partial enlarged schematic diagram of D in the middle;

[0030] Figure 6 for Figure 3 Cross-sectional view in the BB direction;

[0031] Figure 7 for Figure 6 A partial enlarged schematic diagram of the upper part of the battery cell;

[0032] Figure 8 for Figure 7 A partial enlarged schematic diagram of middle E;

[0033] Fig. 9 for Figure 3 Cross-sectional view in CC direction;

[0034] Fig.10 for Fig. 9 A partial enlarged schematic diagram of the upper part of the battery cell;

[0035] Fig.11 This is a schematic structural diagram of an insulating plate according to an embodiment of the present invention;

[0036] Fig.12 for Fig.11 A top view of the insulating panel shown;

[0037] Fig.13 for Fig.11 A side view of the insulating panel shown;

[0038] Fig.14 This is a schematic structural diagram of a connecting sheet according to an embodiment of the present invention;

[0039] Fig.15 for Fig.14 A front view of the connecting piece shown;

[0040] Fig.16 for Fig.14 A bottom view of the connecting piece shown;

[0041] Fig.17 A side view of a connecting piece with a bending angle according to an embodiment of the present invention;

[0042] Fig.18 A side view of a connecting piece with another bending angle according to an embodiment of the present invention;

[0043] Fig.19 A side view of a connecting piece with another bending angle according to an embodiment of the present invention;

[0044] Fig. 20 for Fig.14 The schematic diagram of the structure when the connecting piece is not bent is shown.

[0045] Description of reference numerals:

[0046] 1. Connecting piece; 101. First connecting area; 111. Welding part; 102. Second connecting area; 103. Connecting section; 113. Bending part; 123. First main body; 133. Second main body; 104. Through hole; 2. Shell; 3. Cover plate; 4. Pole; 401. Column; 402. Bottom plate; 5. Pole group; 501. Pole ear; 511. Root; 521. Connecting part; 6. Lower plastic part; 7. Insulating plate; 701. Through groove; 8. Sealing ring; 9. Upper plastic part. DETAILED DESCRIPTION

[0047] 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.

[0048] Combine the following Figures 1 to 20 , describing an embodiment of the present invention.

[0049] According to an embodiment of the present invention, on the one hand, a battery cell is provided, including: a shell 2, a cover assembly, a pole group 5 and a connecting piece 1. The shell 2 has an open end; the cover assembly is arranged at the open end of the shell 2 to close the shell 2, and the cover assembly includes a cover 3 and a pole 4 arranged on the cover 3; the pole group 5 is arranged inside the shell 2, and a pole ear 501 is arranged on the side of the pole group 5 facing the cover assembly; the connecting piece 1 is located between the cover assembly and the pole group 5, and the connecting piece 1 includes a first connecting area 101, a second connecting area 102 and a connecting section 103, and the connecting section 103 is fixedly connected between the first connecting area 101 and the second connecting area 102, and the connecting section 103 includes a bending portion 113, and the bending portion 113 is bent in an arc shape so that the first connecting area 101 and the second connecting area 102 are connected. The connection areas 102 are arranged opposite to each other, the pole lug 501 passes through the first connection area 101 from the lower side upward and then bends toward the upper surface of the first connection area 101, the pole lug 501 is welded to the upper surface of the first connection area 101, and the upper surface of the second connection area 102 is welded to the lower surface of the pole 4; the distance between the upper surface of the first connection area 101 and the lower surface of the second connection area 102 is F, the size of the portion of the pole lug 501 located on the upper side of the first connection area 101 along the up-down direction is b, and the inner radius of the circle where the arc-shaped bending portion 113 is located is R, wherein b+0.2mm≤F≤R. The up-down direction refers to the direction along Figures 4 to 10 The direction of "up" indicated by the arrow in the middle is Figure 2 The Y-axis in the rectangular coordinate system is in the same direction, the "up" indicated by the arrow is in the same direction as the positive direction of the Y-axis, and the "down" indicated by the arrow is in the same direction as the negative direction of the Y-axis; the bending portion 113 has a certain thickness, and after being bent in an arc shape, in the side view of the connecting piece 1, the bending portion 113 is a part of a circular ring, and the circular ring has a larger outer ring and a smaller inner ring, and the inner circle refers to the circle where the smaller inner ring is located.

[0050] In the battery cell using the present embodiment, the first connection area 101 of the connecting sheet 1 is welded to the pole ear 501 and the second connection area 102 is welded to the pole post 4, so as to realize the electrical connection between the pole group 5 and the pole post 4. In addition, the connecting section 103 on the connecting sheet 1 is provided to include a bending portion 113 bent in an arc shape, so that the first connection area 101 and the second connection area 102 are opposite to each other, and the connecting sheet 1 is bent as a whole. On the one hand, it is convenient to weld the connecting sheet 1 with the pole ear 501 and the pole post 4 respectively, and on the other hand, it can improve the structural strength of the connecting sheet 1. By arranging the pole ear 501 to pass through the first connection area 101 from the lower side of the first connection area 101 upward and then bend toward the upper surface of the first connection area 101, so that the bent pole ear 501 part is in contact with the upper surface of the first connection area 101, then the pole ear 501 and the first connection area 101 are limited to each other in the upper and lower directions, so as to ensure the relative stability in the subsequent welding process, which is beneficial to improve the welding quality and can reduce the difference between the pole ear 501 and the first connection area 101 has a total thickness dimension in the up-down direction after being assembled. At the same time, by limiting the distance F between the upper surface of the first connection area 101 and the lower surface of the second connection area 102, the dimension b of the portion of the pole ear 501 located on the upper side of the first connection area 101 in the up-down direction, and the inner circle radius R of the circle where the arc-shaped bending portion 113 is located to satisfy b+0.2mm≤F≤R, the distance F between the upper surface of the first connection area 101 and the lower surface of the second connection area 102 is associated with the dimension b of the portion of the pole ear 501 located on the upper side of the first connection area 101 in the up-down direction, and the inner circle radius R of the circle where the arc-shaped bending portion 113 is located. While ensuring that the pole ear 501 will not interfere with the second connection area 102, the total dimension of the connecting sheet 1 in the up-down direction is reduced as much as possible, so that the second connection area 102 will not crush the pole ear 501 and will not overlap and short-circuit with the pole ear 501, while improving the internal space utilization of the battery cell as much as possible, which is beneficial to improving the capacity and energy density of the battery cell.

[0051] It should be noted that the connecting piece 1 needs to be Fig. 20 The expanded state shown is bent to Figures 14 to 19After being bent into the state shown in the figure, the connecting sheet 1 is assembled into the battery cell. The connecting sheet 1 is bent from the bending portion 113 on the connecting section 103, and the fold extends along the width direction of the connecting sheet 1. The first connecting area 101 and the second connecting area 102 on the bent connecting sheet 1 are opposite to each other, so the connecting sheet 1 is bent as a whole, and the space between the electrode group body and the cover plate assembly can be fully utilized; the distance F between the upper surface of the first connecting area 101 and the lower surface of the second connecting area 102 is the minimum distance between the upper and lower layers of the bent connecting sheet 1; the pole ear 501 includes a root portion 511 and a connecting portion 521 connected to each other, and the connecting portion 521 is arranged at an angle with the root 511, the root 511 is connected to the electrode group body, and the connecting portion 521 is connected to the end of the root 511 away from the electrode group body, and the root 511 passes through the first connecting area 101. The connecting portion 521 is located on the upper side of the first connecting area 101 and is welded to the first connecting area 101. Preferably, the root 511 is perpendicular to the connecting portion 521, and the connecting portion 521 is parallel to the first connecting area 101 and is in contact with the upper surface of the first connecting area 101. In the process of connecting the traditional pole ear and the connecting sheet, the pole ear is usually bent into an "S" shape first, and then the upper surface of the pole ear 501 is welded to the lower surface of the connecting sheet. After the two are welded, the total thickness dimension along the up and down direction is larger. The pole ear 501 of this embodiment passes through the first connecting area 101 on the connecting sheet 1 from bottom to top and then is bent. The lower surface of the connecting portion 521 formed after bending is in contact with and welded to the upper surface of the first connecting area 101. The pole ear 501 makes full use of the space above the first connecting area 101, so the total thickness of the two can be reduced.

[0052] Among them, since the first connection area 101 and the second connection area 102 are arranged opposite to each other, at least part of the area of ​​the connection portion 521 is located in the gap between the first connection area 101 and the second connection area 102. Therefore, it is necessary to ensure that the distance F between the first connection area 101 and the second connection area 102 is greater than the thickness b of the connection portion 521 (that is, the thickness of the tab 501). If the distance F between the upper surface of the first connection area 101 and the lower surface of the second connection area 102 is less than b+0.2mm, the distance between the second connection area 102 and the first connection area 101 is too small, and there is a possibility that the second connection area 102 may crush the connection portion 521 of the tab 501 or the second connection area 1 02 and the connection part 521 overlap risk. When the second connection area 102 overlaps the connection part 521, the second connection area 102 and the connection part 521 are short-circuited, which will change the current flow direction in the battery cell and is highly dangerous. If the distance F between the upper surface of the first connection area 101 and the lower surface of the second connection area 102 is greater than the inner radius R of the circle where the arc-shaped bending part 113 is located, that is, the second connection area 102 is located above the second main body 133, and the connecting piece 1 is designed to open outward, then the distance between the second connection area 102 and the first connection area 101 is too large, and too much internal space is occupied in the up and down directions, which is not conducive to improving the internal space utilization rate of the battery cell. Among them, the top refers to Figure 8 and Fig.17 The direction of "up" indicated by the arrow in the middle is Figure 2 The positive direction of the Y axis of the rectangular coordinate system shown is the same; the following refers to Figure 8 and Fig.17 The direction of "down" indicated by the arrow in the middle is Figure 2 The negative direction of the Y axis of the rectangular coordinate system shown is in the same direction.

[0053] In one embodiment, the inner radius R of the circle where the arc-shaped bending portion 113 is located and the body thickness H1 of the connecting piece 1 satisfy the following relationship: 1.5×H1≤R≤2×H1. It should be noted that the body thickness of the connecting piece 1 refers to the thickness of the connecting piece 1. Fig. 20 In the unfolded state shown in FIG. 1 , the dimension in the direction perpendicular to the unfolded plane, that is, the connecting piece 1 is as follows Fig.17In the bent state shown, the first connection area 101, the second connection area 102, the first body part 123, and the second body part 133 are respectively dimensioned in the up-down direction, and the ring width of the ring where the bending part 113 is located. If R is less than 1.5×H1, the bending radius of the bending part 113 is too small, the connection piece 1 is difficult to bend and formed, and it is easy to break, and the overall yield is low; if R is greater than 1.5×H1, the bending radius of the bending part 113 is too large, the overall dimension of the connection piece 1 in the up-down direction after bending is large, and the connection piece 1 occupies too much space inside the battery cell, which is not conducive to improving the utilization rate of the internal space of the battery cell. Therefore, by setting 1.5×H1≤R≤2×H1, it can not only ensure that the connection piece 1 is smoothly formed and the overall yield is high during the production process, but also avoid that the connection piece 1 occupies too much space in the up-down direction, thereby improving the utilization rate of the internal space of the battery cell. The overall size of the connecting piece 1 along the up-down direction after being bent refers to the distance between the upper surface of the second body portion 133 and the lower surface of the first connecting area 101 along the up-down direction.

[0054] Preferably, the inner circle radius R of the circle where the arc-shaped bending portion 113 is located is 1.5×H1.

[0055] In one embodiment, the value range of the body thickness H1 of the connecting sheet 1 is: 0.6mm-1mm. The thicknesses of the first connecting area 101, the second connecting area 102 and the connecting section 103 are all equal, all H1. If the body thickness H1 of the connecting sheet 1 is less than 0.5mm, the connecting sheet 1 is too thin, the strength is insufficient, it is easy to deform or even break, and the reliability is poor; if the body thickness H1 of the connecting sheet 1 is greater than 1mm, the connecting sheet 1 is too thick, it is not easy to bend, and the weight is too large, the cost is high, and it is not conducive to improving the volume energy density of the battery cell. Therefore, by setting the body thickness H1 of the connecting sheet 1 to a value within the range of 0.5mm-1mm, it can be ensured that the connecting sheet 1 has sufficient strength, ensures the stability of the state of the connecting sheet 1 after bending, avoids deformation or breakage, and avoids the connecting sheet 1 from increasing the difficulty of the bending process due to excessive thickness and strength, thereby ensuring that the connecting sheet 1 can be bent smoothly, improving processing efficiency, and avoiding the excessive weight of the connecting sheet 1, thereby reducing costs and improving the energy density of the battery cell.

[0056] The performance of the battery cells was experimentally verified by using different parameter values ​​of the distance F between the upper surface of the first connection area 101 and the lower surface of the second connection area 102. The experimental verification results of the influence of different parameter values ​​of F on the battery cells are described below.

[0057] Table 1 Effects of different values ​​of F on the battery cell

[0058]

[0059] It can be seen from Table 1 that for the battery cells of Implementation Examples 1 to 5, the distance F between the upper surface of the first connection area 101 of the connecting sheet 1 and the lower surface of the second connection area 102, the dimension b of the portion of the pole ear 501 located on the upper side of the first connection area 101 along the up-down direction, and the inner circle radius R of the ring where the arc-shaped bending portion 113 is located all satisfy the relationship b+0.2mm≤F≤R, that is, F takes a value between b+0.2mm and R. Within the limited range of the application itself, the connecting sheet 1 is assembled into the battery cell, and there is no abnormal bending of the pole ear, no crushing injury, overlap short circuit, and the battery cell is in good condition; however, for Compared with the battery cells in Case 1 and Comparative Case 2, the value of b is 0.5mm, the value of F is 0.6mm, and F is less than b+0.2mm, both of which are not within the scope defined in the present application. When the connecting piece 1 is assembled into the battery cell, there is an indentation on the front side of the pole ear, and there is a risk of the second connecting area of ​​the connecting piece overlapping the pole ear. For the battery cell in Comparative Case 3, the value of R is 0.9mm, the value of F is 1.2mm, and F is greater than R, which is not within the scope defined in the present application. There is no abnormal bending of the pole ear, and no crushing or overlapping short circuit. However, the space occupied by the connecting piece 1 in the up and down directions is more than 0.3mm, which has an impact on the improvement of the battery cell capacity.

[0060] In summary, when the distance F between the upper surface of the first connection area 101 and the lower surface of the second connection area 102 is within the range of b+0.2mm≤F≤R specified in the present application, it can ensure that the connecting piece 1 is assembled into the battery cell, there is no abnormal bending of the pole ear, no crushing or overlapping short circuit, and the battery cell is in good condition, and the total size of the connecting piece 1 along the up and down directions can be reduced as much as possible, thereby improving the utilization rate of the internal space of the battery cell, which is beneficial to increasing the capacity of the battery cell.

[0061] In addition, for the battery cells of implementation cases 1 to 5, R=1.5×H1, satisfying the relationship of 1.5×H1≤R≤2×H1. Within the limited range of the present application, the connecting piece 1 is assembled into the battery cell, and there is no abnormal bending of the tabs, no crushing, overlapping or short circuit, and the battery cell is in good condition. However, for the battery cell of comparative case 4, the value of H1 is 1mm, the value of R is 2.5mm, and R is greater than 2×H1, which is not within the limited range of the present application. The connecting piece 1 is assembled into the battery cell. Although there is no abnormal bending of the tabs, and there is no crushing or overlapping short circuit, the space occupied by the connecting piece 1 in the up and down direction is more than 0.5mm, and the space occupied in the height direction of the battery cell is too much, which is not conducive to improving the internal space utilization of the battery cell and has an impact on the improvement of the battery cell capacity; for the battery cell in comparison case 5, the value of H1 is 0.6mm, and the value of R is 0.8mm. R is less than 1.5×H1, which is not within the scope specified in this application. The bending space of the connecting piece is small, and the surface of the bending part is not smooth, which affects the efficiency of the production line. In summary, when the inner circle radius R of the circular ring where the arc-shaped bending portion 113 is located is within the range of 1.5×H1 to 2×H1, it can not only ensure that the connecting piece 1 is smoothly formed and the overall yield in the production process is high, but also avoid the connecting piece 1 from occupying too much space in the up and down direction, thereby improving the internal space utilization of the battery cell.

[0062] It should be noted that the connecting piece 1 is composed of Fig. 20 The unfolded state shown is bent into Figures 14 to 19 In the bent state shown in FIG. 1 , the connecting piece 1 is in an ideal state. Fig.17 In the state shown, the first connection area 101 is parallel to the second connection area 102, but because the connection sheet 1 is made of metal and has a certain bending strength, the connection sheet 1 in the bent state formed after the bending process by the bending device opens a certain angle, as shown in FIG. Figure 18 to Figure 19 In the state shown, the plane where the first connection area 101 is located and the plane where the second connection area 102 is located intersect to form an angle θ.

[0063] In one embodiment, the angle θ between the first connection area 101 and the second connection area 102 is in the range of 0°≤θ≤10°. Figures 4 to 10In the upper and lower directions, there is a certain gap between the first connection area 101 and the second connection area 102. The side of the second connection area 102 away from the first connection area 101 is connected to the pole 4, and the side of the first connection area 101 away from the second connection area 102 is connected to the pole ear 501. If the angle θ between the first connection area 101 and the second connection area 102 is greater than 10°, the angle of the connection piece 1 is too large, and it is not convenient to install it between the pole group 5 and the pole 4. Even after the connection piece 1 is installed in the battery cell, it has a large thrust on the pole ear 501 and the pole 4, and there is a risk of crushing the pole ear 501, thereby causing a short circuit and affecting the quality of the battery cell. Therefore, by setting the angle θ between the first connection area 101 and the second connection area 102 to a value within the range of 0° to 10°, it can be ensured that the bent connection piece 1 can be smoothly installed between the pole 4 and the pole group 5, and the stability is good, which can avoid damaging the pole ear 501, thereby ensuring the quality of the battery cell.

[0064] It should be noted that, for the bending process of the connecting sheet 1, the connecting sheet 1 can be bent to any angle between 0° and 10° at which the angle θ between the first connecting area 101 and the second connecting area 102 is preferably in the range of 0°≤θ≤8°.

[0065] In one embodiment, Fig.17 As shown, the angle between the first connection area 101 and the second connection area 102 is 0°, that is, the first connection area 101 is parallel to the second connection area 102, which is convenient for installation and does not apply thrust to the pole 4 and the pole ear 501, which is beneficial to protecting the internal structure of the battery cell. When the connecting piece is in a bent state and the angle θ between the first connection area 101 and the second connection area 102 is 0°, the first body portion 123 and the first connection area 101 are on the same plane, and the vertical distance from the second connection area 102 to the first connection area 101 is less than the vertical distance from the second body portion 133 to the first connection area 101.

[0066] In addition, in other embodiments, Fig.18 As shown, the angle θ between the first connection area 101 and the second connection area 102 is 5°, and there is a small opening angle between the first connection area 101 and the second connection area 102, so the pressure required to be applied during the bending of the connection sheet 1 can be appropriately reduced, the requirements for processing equipment are reduced, the cost is reduced, and the processing efficiency can be improved. It should be noted that the angle between the first connection area 101 and the second connection area 102 is small. After being installed in the battery cell, only a small pressure needs to be applied to the connection sheet 1 between the pole 4 and the pole group 5, and the pole 4 and the pole ear 501 will not be damaged.

[0067] In addition, in other embodiments, Fig.19As shown, the included angle θ between the first connection area 101 and the second connection area 102 is 8°, which can also meet the assembly requirements and further improve the processing efficiency.

[0068] It should be noted that when the angle θ between the first connection area 101 and the second connection area 102 is greater than 0°, the distance F between the upper surface of the first connection area 101 and the lower surface of the second connection area 102 refers to the minimum distance between the upper surface of the first connection area 101 and the lower surface of the second connection area 102.

[0069] In one embodiment, the connecting section 103 further includes: a first main body portion 123 connected between the first connecting area 101 and the bending portion 113, and a second main body portion 133 connected between the bending portion 113 and the second connecting area 102, the first main body portion 123 and the first connecting area 101 are on the same plane, the second main body portion 133 is higher than the second connecting area 102 or flush with the second connecting area 102, and the distance between the upper surface of the second main body portion 133 and the upper surface of the second connecting area 102 in the up-down direction is H0; the pole 4 includes a column 401 and a bottom plate 402, the column 401 is inserted into a pole hole opened on the cover plate 3, the bottom plate 402 is located on the lower side of the cover plate 3, the size of the bottom plate 402 in the up-down direction is K, and the distance between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 is N, wherein, (K+N)-H0≥N. The second body portion 133 is higher than the second connection area 102. The second body portion 133 is higher than the second connection area 102 in the up-down direction. The up-down direction refers to Figures 4 to 10 The middle arrow points to the "up and down" direction; the lower side refers to Figures 4 to 10 On the side of the direction of "down" indicated by the middle arrow, the lower side of the cover plate 3 faces the inside of the housing 2. By setting the distance H0 between the upper surface of the second body part 133 and the upper surface of the second connection area 102 in the up-down direction, the dimension K of the bottom plate 402 in the up-down direction, and the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 to satisfy the relationship of (K+N)-H0≥N, the distance H0 between the upper surface of the second body part 133 and the upper surface of the second connection area 102 in the up-down direction, the dimension K of the bottom plate 402 in the up-down direction, and the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 are associated, and the size of each component is designed according to the actual space inside the battery cell, while making full use of the internal space of the battery cell, ensuring that the bending position of the connecting sheet 1 does not interfere with the lower plastic part 6, avoiding mutual extrusion between the lower plastic part 6 and the connecting sheet 1 to cause deformation, thereby ensuring the quality of the battery cell.

[0070] It should be noted that the pole hole is a through hole that penetrates the cover plate 3 in the up-down direction. The projection area of ​​the bottom plate 402 of the pole 4 on a plane perpendicular to the up-down direction is larger than the projection area of ​​the column 401 on the plane, and larger than the projection area of ​​the pole hole on the plane. Therefore, the bottom plate 402 is limited by the cover plate 3 and the lower side of the cover plate 3; a sealing ring 8, a lower plastic part 6, and an upper plastic part 9 are provided between the pole 4 and the pole hole to ensure that the pole 4 is insulated from the cover plate 3, the sealing ring 8 is compressed, and the bottom plate 402 is There is a partial structure of the sealing ring 8 and a partial structure of the lower plastic part 6 between the upper surface and the lower surface of the cover plate 3. The distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 is equal to the size of the sealing ring 8 between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 after being compressed in the up-down direction. Then (K+N) represents the distance ΔH between the lower surface of the pole 4 and the lower surface of the cover plate 3. Then the formula (K+N)-H0≥N is expressed as ΔH-H0≥N. Further combined Figure 5 and Figure 8 As shown, the upper surface of the second connection area 102 of the connecting piece 1 is in contact with the lower surface of the pole 4, and the portion of the connecting piece 1 that is not welded to the pole 4 is also located between the lower plastic part 6 and the pole group 5 on the lower side of the cover plate 3. The lower surface of the area on the lower plastic part 6 corresponding to the portion of the connecting piece 1 that is not welded to the pole 4 is flush with the upper surface of the bottom plate 402. Since the second body portion 133 is higher than the second connection area 102 or flush with the second connection area 102, the second body portion 133 must include the distance from the cover plate 3 to the connecting piece 1 in the up and down direction. The nearest position, H0 is the distance between the upper surface of the second body portion 133 and the upper surface of the second connection area 102 along the up-down direction, H0≥0, then (K+N)-H0 represents the minimum distance between the connecting piece 1 and the cover plate 3 along the up-down direction, if (K+N)-H0 is less than the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3, there will be a situation where the bending position of the connecting piece 1 (specifically the second body portion 133) interferes with the lower plastic part 6, the lower plastic part 6 and the connecting piece 1 squeeze each other and cause deformation, affecting the quality of the battery cell.

[0071] Preferably, the second body portion 133 is higher than the second connection area 102, and the second connection area 102 is connected to the connection section 103 in a stepped manner, H0>0, (K+N)-H0>N. Fig.17As shown, when the connecting sheet 1 is in a bent state, the first connecting area 101 and the first body portion 123 are located on the same side and on the same plane, the second connecting area 102 and the second body portion 133 are located on the same side, but the second connecting area 102 and the second body portion 133 are not on the same plane, there is a height difference H0 between the upper surface of the second connecting area 102 and the upper surface of the second body portion 133 in the up-down direction, the vertical distance F from the second connecting area 102 to the first connecting area 101 is smaller than the vertical distance H4 from the second body portion 133 to the first connecting area 101, the total thickness of the connecting sheet in the bent state in the area corresponding to the second connecting area 102 is smaller than the total thickness in the area corresponding to the second body portion 133, and further combined with Figures 7 and 8 As shown, the second connection area 102 corresponds to the pole 4, the second body part 133 is located in the gap between the lower plastic part 6 and the pole group, the lower surface of the pole 4 is lower than the lower surface of the lower plastic part 6 corresponding to the second body part 133, and the distance between the pole 4 and the pole group 5 is small. Therefore, by setting the second connection area 102 and the connecting section 103 to be connected in a stepped manner, the distance H0 between the upper surface of the second body part 133 and the upper surface of the second connection area 102 in the up-down direction, the size K of the bottom plate 402 in the up-down direction, and the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 satisfy the relationship (K+N)-H0>N. When the connecting sheet 1 is in a bent state, it is more matched with the spatial layout inside the battery cell, can make full use of the internal space of the battery cell, improve the internal space utilization rate of the battery cell, and is beneficial to improve the capacity of the battery cell. In addition, by setting the distance from the second body part 133 to the first connection area 101 to be larger, it is more convenient to bend the connecting sheet 1 from the bending portion 113, which is beneficial to improve the processing efficiency. The lower surface refers to the Figure 8 The surface in the direction of "down" pointed by the middle arrow; since the first main body portion 123 and the first connection area 101 are on the same plane, the vertical distance from the second main body portion 133 to the first connection area 101 is equal to the vertical distance from the second main body portion 133 to the first main body portion 123.

[0072] In one embodiment, the dimension K of the bottom plate 402 along the up-down direction has a value range of: 1.5mm≤K≤2.5mm. Among them, the dimension of the bottom plate 402 along the up-down direction is the thickness of the bottom plate 402. If the dimension K of the bottom plate 402 along the up-down direction is less than 1.5mm, the thickness of the bottom plate 402 is too small, the structural strength is weak, the stability of the pole 4 is poor, and the quality of the battery cell is affected; if the dimension K of the bottom plate 402 along the up-down direction is greater than 2.5mm, the thickness of the bottom plate 402 is too large, the cost is high, and the weight is too large, which is not conducive to improving the energy density of the battery cell. Therefore, by setting the dimension K of the bottom plate 402 along the up-down direction to a value within the range of 1.5mm to 2.5mm, it can not only ensure that the pole 4 has sufficient structural strength and the quality of the battery cell, but also reduce the weight and cost of the pole 4 as much as possible, which is conducive to improving the energy density of the battery cell. Considering the structural cost, preferably, the dimension K of the bottom plate 402 along the up-down direction is 2mm.

[0073] In one embodiment, the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 has a value range of 0.6 mm ≤ N ≤ 1 mm. Part of the structure of the sealing ring 8 and part of the structure of the lower plastic part 6 extend between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3. If the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 is less than 0.6 mm, the distance between the bottom plate 402 and the cover plate 3 is too small, which will cause excessive extrusion of the sealing ring 8 and the lower plastic part 6, and there is a risk of crushing the sealing ring 8 and the lower plastic part 6, thereby affecting the insulation between the pole 4 and the cover plate 3; if the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 is greater than 1 mm, the distance between the bottom plate 402 and the cover plate 3 is too large, and the sealing ring 8 cannot be fully compressed, affecting the sealing performance. Therefore, by setting the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 to be in the range of 0.6 mm to 1 mm, it is possible to prevent the bottom plate 402 of the pole 4 from crushing the sealing ring 8 or the lower plastic part 6, thereby ensuring the insulation between the pole 4 and the cover plate 3, and to ensure that the pole 4 can fully compress the sealing ring 8, thereby ensuring the sealing between the pole 4 and the cover plate 3.

[0074] The performance of the battery cells was verified experimentally by using battery cells with different parameter values ​​for the distance H0 along the up-down direction between the upper surface of the second main body 133 and the upper surface of the second connection area 102, the dimension K of the bottom plate 402 along the up-down direction, and the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3. The experimental verification results of the influence of different parameter values ​​of H0, K, and N on the battery cells are described below.

[0075] Table 2 Effects of different values ​​of H0, K, and N on the battery cell

[0076]

[0077] It can be seen from Table 2 that for the battery cells of Implementation Cases 6 to 8, the relationship between the distance H0 along the vertical direction between the upper surface of the second body portion 133 of the connecting piece 1 and the upper surface of the second connecting area 102, the dimension K of the bottom plate 402 along the vertical direction, and the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 is (K+N)-H0>N. Within the limited range of the application, the connecting piece 1 is assembled into the battery cell, and there is no abnormality in the bending position of the connecting piece, and there is no pressure damage to the lower plastic. The battery cell is in good condition. For the battery cells of Implementation Cases 9 to 10, (K+N)-H0=N. Within the limited range of the application, the connecting piece 1 is assembled into the battery cell, and there is no abnormality in the bending position of the connecting piece, and there is no pressure damage in contact with the lower plastic. The battery cell is in good condition. However, for the battery cell of comparative case 6, the value of N is 0.6mm, the value of (K+N)-H0 is 0.5mm, (K+N)-H0 is less than N, which is not within the scope defined in the present application, and the value of (K+N)-H0 differs from the value of N by 0.1mm. When the connecting piece 1 is assembled into the battery cell, the bending position of the connecting piece interferes with the lower plastic, and the lower plastic is squeezed and deformed; for the battery cells of comparative cases 7 and 8, (K+N)-H0 is less than N, which is not within the scope defined in the present application, and the value of (K+N)-H0 differs from the value of N by 0.2mm. The distance from the lower surface of the pole 4 to the lower surface of the cover plate 3 is too small. When the connecting piece 1 is assembled into the battery cell, the bending position of the connecting piece interferes with the lower plastic, and the lower plastic and the connecting piece are squeezed and deformed.

[0078] In summary, when the distance H0 between the upper surface of the second main body 133 and the upper surface of the second connection area 102 along the up and down direction, the dimension K of the bottom plate 402 along the up and down direction, and the distance N between the upper surface of the bottom plate 402 and the lower surface of the cover plate 3 satisfy the relationship (K+N)-H0≥N, the internal space of the battery cell can be fully utilized while ensuring that the bending position of the connecting piece 1 does not interfere with the lower plastic part 6, avoiding deformation caused by mutual squeezing of the lower plastic part 6 and the connecting piece 1, thereby ensuring the quality of the battery cell.

[0079] In one embodiment, N through holes 104 are provided on the bending portion 113. In the width direction of the connecting section 103, the distance between the two sides of the bending portion 113 that are farthest apart is L, and the sum of the dimensions of the N through holes 104 in the width direction of the connecting section 103 is W, wherein L and W satisfy the relationship: 0.3≤W / L≤0.7, and N is a positive integer greater than or equal to 1. It should be noted that the connecting section 103 includes the bending portion 113, and the connecting section 103 is suitable for bending at the bending portion 113; the width direction refers to the width along the connecting section 103. Figure 15 to Figure 16 The "width direction" indicated by the arrow in the middle is Figure 2The X-axis direction in the rectangular coordinate system is in the same direction; the two sides on the bending portion 113 that are farthest apart refer to the two outermost sides of the bending portion 113 in the width direction. By constructing the bending portion 113 on the connecting section 103 between the first connecting area 101 and the second connecting area 102, and providing a through hole 104 on the bending portion 113, the solid part of the bending portion 113 in the width direction is reduced, so that the bending strength of this part is reduced to a certain extent, thereby facilitating the bending of the connecting piece 1 from the bending portion 113, reducing the processing difficulty and improving the production efficiency. In addition, by limiting the sum of the dimensions W of all the through holes 104 in the width direction and the bending portion 113 in the width direction, the bending strength of the bending portion 113 is reduced. The ratio of the distance L between the two outermost sides is within the range of 0.3 to 0.7, which can avoid the insignificant reduction in the strength of the bending portion 113 due to the through hole 104 being too small relative to the bending portion 113, and can also avoid the excessively low strength of the bending portion 113 due to the through hole 104 being too large relative to the bending portion 113. This can ensure that the connecting piece 1 can be bent smoothly, and can also ensure the stability of the shape of the connecting piece 1 after bending, ensure the quality of the connecting piece 1, and facilitate mass production.

[0080] It should be noted that the bending portion 113 is a section on the connecting section 103, and the first body portion 123, the bending portion 113, and the second body portion 133 are connected in sequence. By opening the through hole 104 on the bending portion 113, the strength of the bending portion 113 is weakened, so that the connecting piece 1 is bent from the bending portion 113. In the width direction of the connecting section 103, if the ratio between the size W of the through hole 104 and the size L of the bending portion 113 is less than 0.3, the area occupied by the through hole 104 on the bending portion 113 is too small, that is, the size of the through hole 104 relative to the bending portion 113 is too small, and the weakening effect on the strength of the bending portion 113 is It is not obvious, the bending portion 113 still has a high bending strength, the bending process of the connecting piece 1 is more laborious, the production and processing efficiency is low, and it is difficult to achieve mass production; if the ratio between the size W of the through hole 104 and the size L of the bending portion 113 is greater than 0.7, the area occupied by the through hole 104 on the bending portion 113 is too large, that is, the through hole 104 is too large relative to the size of the bending portion 113, and the remaining solid part of the bending portion 113 except the through hole 104 is too small, and the strength of the bending portion 113 is too small. Although it is easy to achieve the bending of the connecting piece 1, the strength of the connecting piece 1 after bending is not good, the shape is unstable, the quality is poor, and it does not meet the standards.

[0081] In one embodiment, N=1, one through hole 104 is formed on the bending portion 113 , and W is the dimension of the through hole 104 along the width direction of the connecting section 103 .

[0082] In addition, in other embodiments, N is a positive integer greater than 1, and a plurality of through holes 104 are provided on the bending portion 113 , and W is the sum of the dimensions of each through hole 104 along the width direction of the connecting section 103 .

[0083] In one embodiment, the dimension L of the bending portion 113 along the width direction of the connecting section 103 ranges from 40 mm to 50 mm. The connecting piece 1 is bent at the bending portion 113, and the fold is along the width direction of the connecting section 103. If the dimension L of the bending portion 113 along the width direction is greater than 50 mm, the dimension of the bending portion 113 along the width direction is too large, the strength is high, the bending process is more laborious, and the processing efficiency is low; if the dimension L of the bending portion 113 along the width direction is less than 40 mm, the dimension of the bending portion 113 along the width direction is too small. Although the bending is easy to achieve, the strength of the bending connecting piece 1 is poor, the shape is unstable, and the quality is poor. Therefore, by setting the dimension L of the bending portion 113 along the width direction of the connecting section 103 to be in the range of 40mm-50mm, it can be ensured that the connecting piece 1 can be smoothly bent from the bending portion 113 to improve the processing efficiency, and it can also be ensured that the connecting piece 1 after bending still has sufficient strength, and the stability of the bending state of the connecting piece 1 can be ensured, thereby improving the quality and reliability of the connecting piece 1.

[0084] In one embodiment, the dimension W of the through hole 104 along the width direction of the connecting section 103 ranges from 15 mm to 35 mm. If the width dimension W of the through hole 104 is less than 15 mm, the through hole 104 is too small, the effect of weakening the strength of the bending portion 113 is poor, the bending process of the connecting piece 1 is more laborious, and the production and processing efficiency is low; if the width dimension W of the through hole 104 is greater than 35 mm, the through hole 104 is too large, the solid part on the bending portion 113 is too small, the strength of the bending portion 113 is too small, the strength of the bending connecting piece 1 is poor, the shape is unstable, the reliability is poor, and there is even a risk of breaking. Therefore, by setting the dimension W of the through hole 104 along the width direction of the bending portion 113 to be in the range of 15mm-35mm, the bending strength of the connecting section 103 can be weakened to a certain extent, thereby improving the processing efficiency of the bending process of the connecting piece 1, and avoiding the strength of the connecting piece 1 at the bending portion 113 being too low, thereby ensuring the stability and reliability of the connecting piece 1.

[0085] In one embodiment, further combining Figure 15 to Figure 16As shown, the body width of the connecting section 103 is L0, and the body width L0 of the connecting section 103 and the dimension L of the bending portion 113 along the width direction of the connecting section 103 satisfy the relationship: 0≤(L0-L) / L0<0.2. The body of the connecting section 103 includes a first body portion 123 connected between the first connecting area 101 and the bending portion 113, and a second body portion 133 connected between the bending portion 113 and the second connecting area 102. The first body portion 123, the bending portion 113, and the second body portion 133 are sequentially connected to form the connecting section 103, and the bending portion 113 is a section of the connecting section 103 located in the middle of the connecting section 103. If (L0-L) / L0 is greater than 0.2, the dimension of the bending portion 113 along the width direction is too small, the strength is poor, the shape of the connecting piece 1 is unstable after bending, and there is also a risk of breaking. Therefore, by setting the relationship between the body width L0 of the connecting section 103 and the dimension L of the bending portion 113 along the width direction of the connecting section 103 to satisfy the relationship 0≤(L0-L) / L0<0.2, the size relationship between the bending portion 113 and the body of the connecting section 103 is limited, which can prevent the bending portion 113 from extending beyond the body width of the connecting section 103 and damaging other adjacent parts in the battery cell, and ensure that the bending portion 113 has sufficient structural strength, thereby ensuring the stability of the shape of the connecting piece after bending, thereby further improving safety. Preferably, the body width of the connecting section 103 is the same as the width of the second connecting area 102, wherein the body of the connecting section 103 refers to the first body portion 123 and the second body portion 133.

[0086] It should be noted that the dimension L of the bent portion 113 along the width direction of the connecting section 103 is less than or equal to the body width L0 of the connecting section 103. If the dimension L of the bent portion 113 along the width direction of the connecting section 103 is greater than the body width L0 of the connecting section 103, the bent portion 113 extends beyond the body of the connecting section 103 in the width direction, and is likely to damage other parts inside the battery cell. Therefore, by setting the dimension L of the bent portion 113 along the width direction of the connecting section 103 to be less than or equal to the body width L0 of the connecting section 103, it is possible to prevent the extended portion of the bent portion 113 from damaging other parts inside the battery cell, thereby improving the safety of the battery cell.

[0087] Preferably, the dimension L of the bending portion 113 along the width direction of the connecting section 103 is smaller than the body width L0 of the connecting section 103. When the connecting piece 1 is bent along the bending portion 113, the bending portion 113 is squeezed, and the solid part of the bending portion 113 is moved along the bending portion 113. Fig.16The width direction shown extends toward both sides and may extend beyond the range of the main body width of the connecting section 103. By setting the dimension L of the bending portion 113 along the width direction to be smaller than the main body width L0 of the connecting section 103, along the width direction, there is a certain distance between the two sides of the bending portion 113 and the side edges of the main body of the connecting section 103, that is, a clearance space is reserved for the extension of the bending portion 113 along the width direction, which can prevent the bending portion 113 from extending beyond the range of the main body width of the connecting section 103, thereby preventing the extended portion of the bending portion 113 from piercing other components in the battery cell, thereby improving the safety of the battery cell.

[0088] The dimension L of the bending portion 113 of the connecting piece 1 along the width direction of the connecting section 103, the dimension W and W / L of the through hole 104 along the width direction of the connecting section 103, and the angle θ between the first connecting area 101 and the second connecting area 102 are all parameter values ​​related to the connecting piece 1 itself. The following describes the experimental verification results of the connecting piece 1 with different parameter values ​​of L, W, W / L, and θ.

[0089] Table 3 Verification results of connectors with different parameter values ​​of L, W, W / L, and θ

[0090]

[0091] Among them, implementation case 11 is taken as an example for explanation. Implementation case 11 refers to that the dimension L of the bending portion 113 of the connecting piece 1 along the width direction of the connecting section 103 is 42 mm, the dimension W of the through hole 104 along the width direction of the connecting section 103 is 15 mm, and the value of W / L is 0.357. The connecting piece 1 applying this set of parameters is bent to any angle θ between the first connecting area 101 and the second connecting area 102 between 5° and 10°. The bending efficiency of the connecting piece of implementation case 1 is statistically 25 ea / min, that is, 25 pieces are processed per minute.

[0092] It can be seen from Table 3 that for the connecting sheets of Implementation Cases 11 to Implementation Cases 20, the values ​​of W / L are all in the range of 0.3 to 0.7, that is, within the range specified in the present application, the bending efficiency is between 25 ea / min and 35 ea / min, and the bending state of connecting sheet 1 after bending has no obvious abnormality, and the processing efficiency meets the requirements of mass production; however, for the connecting sheets of Comparative Cases 9 and 10, the values ​​of W / L are both less than 0.3, which are not within the range specified in the present application, and the bending efficiencies are 17 ea / min and 20 ea / min, respectively. Although there is no obvious abnormality in the bending state of the connecting sheets, the efficiency is too low and cannot be mass-produced; for the connecting sheets of Comparative Cases 11 to 13, the values ​​of W / L are all greater than 0.7, which are not within the range specified in the present application, and the bending efficiencies are 37 ea / min, 39 ea / min, and 40 ea / min, respectively. Although the bending efficiency is relatively high, the strength of the connecting sheets after bending is not good, the shape is unstable, and the products do not meet the standards.

[0093] In summary, when the ratio of the dimension W of the through hole 104 along the width direction to the dimension L of the bending portion 113 along the width direction is within the range of 0.3 to 0.7 specified in the present application, it can ensure that the connecting piece 1 can be bent smoothly and that the connecting piece 1 after bending still has sufficient connection strength, thereby ensuring the stability of the connecting piece 1 and realizing mass production.

[0094] Further, the W / L value of the connecting sheet of implementation case 15 is 0.667, the W / L value of the connecting sheet of implementation case 20 is 0.700, and the W / L value of the connecting sheet of implementation case 19 is 0.6. Correspondingly, the bending efficiency of the connecting sheets of implementation cases 15 and 20 is 35 ea / min, and the bending efficiency of the connecting sheet of implementation case 19 is 30 ea / min. The processing efficiency of the connecting sheets of the above three embodiments is relatively high, and the results are optimal; the W / L value of the connecting sheet of implementation case 13 is 0.452, the W / L value of the connecting sheet of implementation case 14 is 0.500, and the W / L value of the connecting sheet of implementation case 18 is 0.500. Correspondingly, the bending efficiency of the connecting sheets of implementation cases 13 and 18 is 30 ea / min, and the bending efficiency of the connecting sheet of implementation case 14 is 31 ea / min, the production efficiency of the connecting pieces of the above three embodiments is moderate; the W / L value of the connecting piece of implementation case 11 is 0.357, the W / L value of the connecting piece of implementation case 12 is 0.405, the W / L value of the connecting piece of implementation case 16 is 0.340, and the W / L value of the connecting piece of implementation case 17 is 0.400. Correspondingly, the bending efficiency of the connecting pieces of implementation cases 11 and 16 is 25 ea / min, and the bending efficiency of the connecting pieces of implementation cases 12 and 17 is 26 ea / min. The connecting pieces of the above four embodiments are relatively inefficient on the basis of meeting the requirements of mass production. It can be further concluded that, under the premise that the W / L value is within the range specified in this application, the larger the W / L value, the higher the bending efficiency, and the more suitable it is for mass production.

[0095] In addition, for the connecting pieces of implementation cases 11 to 20, the dimension L of the bending portion 113 along the width direction is within the range of 40mm-50mm specified in the present application, the dimension W of the through hole 104 along the width direction is within the range of 15mm-35mm specified in the present application, and the value of W / L is within the range of 0.3 to 0.7 specified in the present application. The connecting piece is bent, and the angle between the first connecting area 101 and the second connecting area 102 is processed to the range of 0° to 10° specified in the present application. There is no obvious abnormality in the bending state of the connecting piece 1 after bending, and the processing efficiency meets the requirements of mass production; while for the connecting pieces of comparative cases 9 and 10, the dimension W of the through hole 104 along the width direction is less than 15mm, which is not within the scope of the present application, resulting in a W / L value less than that of the present application. The bending process is more difficult and the bending efficiency is too low. For the connecting pieces of comparative cases 12 and 13, the dimension W of the through hole 104 along the width direction is greater than 35 mm, which is not within the scope of the present application, resulting in a W / L value greater than the scope specified in the present application, and the strength of the bending portion is too low, resulting in poor strength of the connecting piece after bending, unstable shape, and the product does not meet the standards and cannot be produced. For the connecting piece of comparative case 11, although the dimension L of the bending portion 113 along the width direction and the dimension W of the through hole 104 along the width direction are both within the scope specified in the present application, the value of W / L is greater than 0.7, which is not within the scope specified in the present application, and there is also the problem of too low strength of the bending portion, resulting in poor strength of the connecting piece after bending, unstable shape, and the product does not meet the standards and cannot be produced. In summary, when the dimension L of the bending portion 113 along the width direction, the dimension W of the through hole 104 along the width direction, and the value of W / L are all within the scope specified in the present application, it can be ensured that there is no obvious abnormality in the bending state of the connecting piece, and the bending efficiency can meet the requirements of mass production.

[0096] In one embodiment, the first connection area 101 includes a welding portion 111 , and the welding portion 111 is suitable for welding with at least one electrode tab 501 to achieve electrical connection between the connecting sheet 1 and the electrode group 5 .

[0097] In addition, in other embodiments, the first connection area 101 includes a plurality of welding portions 111, each welding portion 111 is suitable for welding with at least one pole ear 501, so that one connecting piece 1 can realize electrical connection with a plurality of pole groups 5 at the same time, that is, a plurality of pole groups 5 are connected to the same integral connecting piece, and the traditional plurality of connecting pieces are optimized into one, the number of parts is reduced, the process is simplified, and cost reduction is achieved.

[0098] Preferably, the first connection area 101 includes two welding parts 111, and two pole ears 501 are welded on each welding part 111 to achieve the connection of the quadrupole battery cell. Correspondingly, the number of poles 4 is two, and the two poles 4 are spaced apart on the cover plate 3, respectively being a positive pole and a negative pole. The number of connecting sheets 1 is two and corresponds to the two poles 4 one by one, one connecting sheet 1 is connected to the positive pole ear of the pole group 5, and the other connecting sheet 1 is connected to the negative pole ear of the pole group 5; the number of pole groups 5 is four, and each pole group 5 has a positive pole ear and a negative pole ear. The connecting sheet 1 has two welding parts 111, and two pole ears are welded on each welding part 111, that is, four positive pole ears are welded on the same connecting sheet 1, and four negative pole ears are welded on another connecting sheet 1. Compared with the traditional quadrupole battery cell using four connecting sheets, this embodiment uses an integral connecting sheet for each positive and negative pole, which reduces the number of connecting sheets 1, reduces the number of parts, and is relatively simple in process, which is conducive to improving the assembly efficiency of the battery cell. Specifically, along Figure 2 In the Z-axis direction of the rectangular coordinate system, there is a gap between the two welding parts 111, and the ends of the two welding parts 111 along the X-axis direction are connected together. Figure 2 The pole lug 501 is arranged in the Z-axis direction of the rectangular coordinate system, and the root 511 of the pole lug 501 passes through the gap between the two welding portions 111 or passes through the sides of the first connection area 101 on both sides in the Z-axis direction, so that the pole lug 501 passes from the lower side of the connecting sheet 1 to the upper side of the first connection area 101. The pole lug 501 passes through the first connection area 101 in the up-down direction and then is bent, so that the portion located above the first connection area 101 is fitted with the upper surface of the welding portion 111, and the bent portion forms a connection portion 521, which is convenient for welding the connection portion 521 to the welding portion 111.

[0099] In one embodiment, the battery cell further includes: an insulating plate 7, the insulating plate 7 is located between the pole group 5 and the connecting sheet 1, and a through slot 701 is provided on the insulating plate 7, and the pole ear 501 passes through the through slot 701 and is welded to the connecting sheet 1. It should be noted that in conventional battery cells, the cover plate assembly is usually fixed to the pole group by directly contacting the lower plastic part 6 in the cover plate assembly with the pole group. However, the lower plastic part 6 is usually pressed on the pole group only by the protrusion protruding away from the cover plate 3, and the force applied to the pole group is uneven, and there is a risk of partial crushing of the pole group. In addition, the lower plastic part 6 has no protective effect on the pole ear 501, and the pole ear 501 is easily squeezed and torn. In the battery cell of this embodiment, an insulating plate 7 is arranged between the electrode group 5 and the cover plate 3, and a through groove 701 is opened on the insulating plate 7, so that the pole ear 501 passes through the through groove 701 on the insulating plate 7 after being folded, which can better protect the pole ear 501 and reduce the risk of poor folding and tearing of the pole ear 501; and the insulating plate 7 is a whole plate, and the cover plate assembly is directly pressed on the insulating plate 7, so the pressure applied by the insulating plate 7 to the electrode group 5 is more uniform, which can better fix the electrode group 5 and reduce the risk of the pole piece being crushed.

[0100] In one embodiment, the dimension H2 of the insulating plate 7 along the vertical direction has a value range of 0.5 mm-1 mm. If the thickness H2 of the insulating plate 7 is less than 0.5 mm, the insulating plate 7 is too thin, the strength is insufficient, and it is easy to be deformed by compression, thereby damaging the pole group 5; if the thickness H2 of the insulating plate 7 is greater than 1 mm, the insulating plate 7 is too thick and the weight is too large. Therefore, by setting the thickness H2 of the insulating plate 7 to a value within the range of 0.5 mm-1 mm, it can be ensured that the insulating plate 7 has sufficient strength, the stability of the structure of the insulating plate 7 is ensured, and damage to the pole group 5 is avoided, and the insulating plate 7 is prevented from being too heavy, thereby reducing costs.

[0101] In one embodiment, the cover assembly further includes a lower plastic part 6, which is supported between the cover 3 and the insulating plate 7. The dimension H3 of the lower plastic part 6 in the vertical direction ranges from 2 mm to 4 mm. Figure 5The dimension in the "up and down" direction indicated by the middle arrow is in the same direction as the thickness direction of the insulating plate 7. If the height of the lower plastic part 6 is less than 2 mm, the height of the lower plastic part 6 is too small, resulting in a small gap between the cover plate 3 and the pole group 5, and there is not enough space to accommodate the pole 4, the pole ear 501 and the connecting piece 1, which may cause the risk of crushing the pole group 5 and affect the quality of the battery cell; if the height of the lower plastic part 6 is greater than 4 mm, the height of the lower plastic part 6 is too large, and the gap between the cover plate 3 and the pole group 5 is too large, which cannot play a good role in fixing the pole group 5 and the connecting piece 1. The internal structure of the battery cell has poor stability, and it is easy to shake and cause the pole ear 501 to tear, which will also damage the quality of the battery cell. Therefore, by setting the height of the lower plastic part 6 to a value within the range of 2 mm-4 mm, it can not only ensure that there is a reasonable space between the cover plate and the pole group to prevent the pole group from being crushed, but also ensure the fixing effect of the cover plate assembly on the pole group 5, thereby ensuring the quality of the battery cell.

[0102] It should be noted that it is difficult to improve the internal space utilization rate of traditional battery cells due to structural reasons. The battery cell of this embodiment increases the insulating plate 7 between the cover plate assembly and the electrode group 5, and the insulating plate 7 can better compress the electrode pieces and diaphragms in the electrode group 5 to maximize the compressed space. The electrode group 5 is fixed by the insulating plate 7, and the demand for the lower plastic part 6 is reduced, and the thickness of the lower plastic part 6 can be reduced accordingly. The height of the lower plastic part 6 in the traditional battery cell without the insulating plate 7 is 5.5mm-7.5mm. The height of the lower plastic part of this embodiment can be reduced by 1.5mm-2mm, which reduces the space occupied by the cover plate assembly. Compared with the traditional battery cell, the total thickness of the cover plate assembly plus the insulating plate 7 can save 1mm-1.5mm of space.

[0103] According to an embodiment of the present invention, in another aspect, a battery pack is provided, comprising: the above-mentioned battery cell. Preferably, there are multiple battery cells.

[0104] 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 housing having an open end; A cover plate assembly is arranged at the open end of the shell to close the shell, and the cover plate assembly includes a cover plate and a pole arranged on the cover plate; A pole group is arranged inside the shell, and a pole ear is arranged on a side of the pole group facing the cover plate assembly; A connecting piece, located between the cover plate assembly and the pole group, the connecting piece includes a first connecting area, a second connecting area and a connecting segment, the connecting segment is fixedly connected between the first connecting area and the second connecting area, the connecting segment includes a bending portion, the bending portion is bent in an arc shape, so that the first connecting area and the second connecting area are arranged opposite to each other, the pole ear passes through the first connecting area from the lower side of the first connecting area upward and then bends toward the upper surface of the first connecting area, the pole ear is welded to the upper surface of the first connecting area, and the upper surface of the second connecting area is welded to the lower surface of the pole; The distance between the upper surface of the first connection area and the lower surface of the second connection area is F, the size of the portion of the tab located on the upper side of the first connection area in the vertical direction is b, and the inner radius of the circle where the arc-shaped bending portion is located is R, wherein b+0.2mm≤F≤R; The connecting section further includes: a first body portion connected between the first connecting area and the bending portion, and a second body portion connected between the bending portion and the second connecting area, the first body portion and the first connecting area are on the same plane, the second body portion is higher than the second connecting area, and the distance between the upper surface of the second body portion and the upper surface of the second connecting area in the vertical direction is H0; the pole includes a column and a bottom plate, the column is inserted into a pole hole provided on the cover plate, the bottom plate is located at the lower side of the cover plate, the size of the bottom plate in the vertical direction is K, and the distance between the upper surface of the bottom plate and the lower surface of the cover plate is N, wherein (K+N)-H0≥N; The value range of the dimension K of the bottom plate in the up-down direction is: 1.5mm≤K≤2.5mm; the value range of the distance N between the upper surface of the bottom plate and the lower surface of the cover plate is: 0.6mm≤N≤1mm.

2. The battery cell according to claim 1, characterized in that: The inner radius R of the circular ring where the arc-shaped bending portion is located and the main body thickness H1 of the connecting piece satisfy the following relationship: 1.5×H1≤R≤2×H1.

3. The battery cell according to claim 2, characterized in that: The thickness H1 of the connecting piece has a value ranging from 0.6 mm to 1 mm.

4. The battery cell according to claim 1, characterized in that: The bending portion is provided with N through holes, and along the width direction of the connecting section, the distance between the two farthest sides of the bending portion is L, and the sum of the dimensions of the N through holes along the width direction of the connecting section is W, wherein L and W satisfy the relationship: 0.3≤W / L≤0.7, and N is a positive integer greater than or equal to 1.

5. The battery cell according to claim 4, characterized in that: The dimension L of the bending portion along the width direction of the connecting section has a value range of 40 mm to 50 mm; And / or, a dimension W of the through hole along the width direction of the connecting section ranges from 15 mm to 35 mm.

6. The battery cell according to claim 1, characterized in that: The body width of the connecting section is L0, and the body width L0 of the connecting section and the dimension L of the bending portion along the width direction of the connecting section satisfy the relationship: 0≤(L0-L) / L0<0.2; And / or, the first connection area includes one or more welding portions, each of which is suitable for welding with at least one electrode tab; And / or, the battery cell further includes: an insulating plate, the insulating plate is located between the electrode group and the connecting piece, the insulating plate is provided with a through slot, and the electrode lug passes through the through slot and is welded to the connecting piece.

7. The battery cell according to claim 6, characterized in that: The value range of the dimension H2 of the insulating plate in the vertical direction is: 0.5mm-1mm; And / or, the cover plate assembly further includes a lower plastic part, the lower plastic part is supported between the cover plate and the insulating plate, and a dimension H3 of the lower plastic part in the up-down direction has a value range of 2 mm-4 mm.

8. A battery pack, characterized in that: include: The battery cell according to any one of claims 1 to 7.

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