Battery cell and battery pack

Abstract

The utility model relates to battery technology field discloses electric core and battery package. Electric core includes casing, apron subassembly, pole group and connecting piece. Through setting up connecting piece has with the first connecting portion of pole connection and with the second connecting portion of tab connection, the second connecting portion is protruding relative to the first connecting portion to the direction close to apron body, the first connecting portion with second connecting portion sets up as the step structure, make second connecting portion occupy the electric core upper space close to apron subassembly place, can reduce the distance between pole group body and apron body to increase the size of pole group body, increase electric core capacity and energy density, limit the ratio h1 / H between the distance h1 that second connecting portion protrudes relative to the first transition area and the size H of tab along Z direction in 0.2 to 0.45 range, can effectively improve the utilization of electric core upper space, satisfy the demand of large capacity electric core, can ensure the structure stability of connecting piece and the use safety of electric core.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to battery cells and battery packs. Background Technology

[0002] With the increasing maturity of battery technology, batteries, as a new type of power battery, are widely used in electric vehicles, and the requirements for battery performance and safety are becoming increasingly stringent. A battery includes components such as a casing, electrode assembly, cover plate, and connecting tabs. The electrode assembly is placed inside the casing, and the cover plate covers the open end of the casing. The electrode assembly and the cover plate are electrically connected through connecting tabs. Part of the connecting tab is welded to the tabs of the electrode assembly, while another part is welded to the terminals on the cover plate, thus allowing the battery's electrical energy to be drawn to the outside. However, the connecting tabs are usually installed in a bent state inside the casing. After bending, the connecting tabs occupy a large amount of space along the height direction of the cell, resulting in low space utilization inside the casing and hindering the improvement of cell capacity and energy density. Utility Model Content

[0003] In view of this, the present invention provides a battery cell and battery pack to solve the problem of low utilization of internal space in the casing.

[0004] In a first aspect, this utility model provides a battery cell, comprising: a housing having an open end; a cover plate assembly covering the open end of the housing, the cover plate assembly including a cover plate body and an electrode post disposed on the cover plate body; an electrode group disposed in the inner cavity of the housing, the electrode group including an electrode group body and an electrode tab, the electrode tab being connected to the side of the electrode group body facing the cover plate body, the electrode tab having a dimension H along the Z direction; and a connecting piece disposed between the cover plate assembly and the electrode group, the connecting piece including a first connecting portion and a second connecting portion, the first connecting portion including an electrode post connecting area and a first transition area, the electrode post connecting area being electrically connected to the electrode post, the first transition area being located below the electrode post connecting area, the second connecting portion being connected along the X direction to one side of the first transition area and electrically connected to the electrode tab, the second connecting portion protruding upward relative to the first transition area, the distance along the Z direction between the upper surface of the second connecting portion and the upper surface of the first transition area being h1, wherein h1 and H satisfy the relationship: 0.2≤h1 / H≤0.45.

[0005] Beneficial effects: By setting the connecting piece to have a first connecting part connected to the pole post and a second connecting part connected to the tab, the second connecting part protrudes towards the cover plate body relative to the first transition area of ​​the first connecting part, that is, the second connecting part is located above the first transition area, so that the first connecting part and the second connecting part are set as a stepped structure. The second connecting part occupies the upper space of the cell near the cover plate assembly in the Z direction. With the tab dimension along the Z direction being fixed, the distance between the pole assembly body and the cover plate body along the Z direction can be reduced, thereby increasing the size of the pole assembly body along the Z direction, increasing the cell capacity and energy density. At the same time, by limiting the ratio h1 / H between the distance h1 of the second connecting part protruding relative to the first transition area and the size H of the tab along the Z direction to be within the range of 0.2 to 0.45, the utilization rate of the upper space of the cell can be effectively improved, meeting the market demand for high-capacity cells, while ensuring the structural stability of the connecting piece and the safety of the cell.

[0006] In one optional embodiment, the dimension H of the electrode tab along the Z direction is in the range of 2.5 mm ≤ H ≤ 4.0 mm; And / or, the distance h1 between the upper surface of the second connecting part and the upper surface of the first transition area along the Z direction is in the range of 0.35 mm ≤ h1 ≤ 1.2 mm.

[0007] Beneficial effects: By limiting H to the range of 2.5 mm to 4.0 mm, the bending operation requirements of the tabs can be met, and the connection piece can be prevented from damaging the electrode assembly body or short-circuiting with the electrode assembly body. It can also avoid space waste and structural stability problems caused by excessively large tab size, thereby improving the utilization rate of internal space of the casing while ensuring the reliability of cell assembly. And / or, by limiting h1 to a value within the range of 0.35 mm to 1.2 mm, the space utilization rate of the cell along the Z direction can be effectively improved, while ensuring the structural stability of the connecting piece and the safety of the cell in use.

[0008] In one optional embodiment, the distance along the Z direction between the lower surface of the second connecting portion and the upper surface of the pole assembly body is h2, wherein 2.35 mm ≤ h2 ≤ 3.2 mm; And / or, the distance along the Z direction between the lower surface of the first transition region and the upper surface of the pole group body is h4, where 1.2 mm ≤ h4 ≤ 1.8 mm.

[0009] Beneficial effects: By limiting h2 to the range of 2.35 mm to 3.2 mm, it is possible to ensure a safe distance between the second connection part and the electrode assembly body, avoiding safety hazards caused by excessive spacing, and to minimize the ineffective space between the electrode assembly body and the cover plate assembly while ensuring safety, thus providing favorable conditions for increasing the size of the electrode assembly body, thereby improving the cell capacity and energy density. And / or, by limiting h4 to the range of 1.2 mm to 1.8 mm, sufficient structural clearance space can be provided for the first transition zone to prevent it from directly contacting the electrode assembly body and causing safety issues. At the same time, the space utilization rate along the Z direction inside the housing can be improved, providing conditions for maximizing the size of the electrode assembly body, thereby balancing the safety and energy density requirements of the cell.

[0010] In one optional embodiment, the cover plate body further includes: a first plastic part, the first plastic part being disposed on the side of the cover plate body facing the electrode assembly, the first plastic part including a blocking area, the blocking area being located between the cover plate body and the electrode tab, and the distance along the Z direction between the upper surface of the second connecting portion and the lower surface of the blocking area being h3, wherein 0.15 mm ≤ h3 ≤ 0.6 mm; And / or, the first connection portion further includes a bending region, the bending region being connected between the pole connection region and the first transition region.

[0011] Beneficial effects: By limiting h3 to the range of 0.15 mm to 0.6 mm, interference between the welding part of the electrode tab and the first plastic part can be avoided, and the upper space of the battery cell can be effectively utilized, further improving the space utilization rate of the battery cell. And / or, by setting a bending area between the pole connection area and the first transition area, it is easy to fold the pole connection area and the first transition area together, thereby ensuring a smooth switch of the connecting piece from the unfolded state to the bent state, and ensuring the smooth progress of the cell assembly process.

[0012] In one optional embodiment, the second connecting portion is provided with a reinforcing rib, and the orthographic projection of the electrode tab along the Z direction on the second connecting portion is spaced apart from the reinforcing rib.

[0013] Beneficial effects: By setting reinforcing ribs on the second connection part, it is ensured that after the connecting piece is welded to the electrode tab, the connecting piece can still maintain a flat state after being subjected to the tensile force of the electrode tab, thus preventing the connecting piece from bending and puncturing the diaphragm and ensuring the safety of the battery cell. At the same time, by setting the orthographic projection of the electrode tab on the second connection part along the Z direction and the reinforcing ribs at intervals, it is ensured that the area on the second connection part that is welded to the electrode tab is a plane, thereby ensuring the welding quality between the electrode tab and the second connection part, and also avoiding the influence of welding on the reinforcing ribs, thus ensuring the effective strengthening effect of the reinforcing ribs on the second connection part.

[0014] In one optional embodiment, the reinforcing rib is formed by a portion of the second connecting part protruding downwards, and the protrusion height of the reinforcing rib is h5, and the thickness of the second connecting part along the Z direction is h0; wherein, h5 and h0 satisfy the relationship: 0.8≤h5 / h0≤1.5; and / or, the value range of h0 is: 0.4 mm≤h0≤1.0 mm.

[0015] Beneficial effects: By setting the reinforcing rib to protrude downwards, the space between the second connecting part and the electrode assembly body is fully utilized. The ratio between the protrusion height of the reinforcing rib and the thickness of the body area of ​​the second connecting part is in the range of 0.8 to 1.5. This can effectively improve the structural strength of the second connecting part, prevent the connecting piece from bending or deforming under the continuous tensile force of the electrode tab, thereby avoiding the safety hazard of the connecting piece potentially puncturing the diaphragm after bending. It can also ensure the feasibility of processing the reinforcing rib and avoid interference between the reinforcing rib and the electrode assembly body, ensuring the stability of the internal structure of the cell. And / or, limiting h0 to the range of 0.4 mm to 1.0 mm can ensure that the connecting piece has sufficient structural strength to meet the requirements of welding and assembly processes, while controlling its own thickness and space occupation, achieving a balance between material cost and cell performance.

[0016] In one optional embodiment, the distance between the orthographic projection of the electrode tab along the Z direction onto the second connecting portion and the distance between the reinforcing rib along the X direction is L, wherein 0.5 mm ≤ L ≤ 5.0 mm; And / or, the distance between the reinforcing rib and the edge of the second connecting portion along the Y direction is W, wherein 0.3 mm ≤ W ≤ 1.2 mm.

[0017] Beneficial effects: By limiting L to the range of 0.5 mm to 5.0 mm, the heat during the electrode welding process can be avoided from affecting the reinforcing rib, ensuring the structural stability of the reinforcing rib. At the same time, the reinforcing effect of the reinforcing rib can be extended to the key stress-bearing parts around the welding area, significantly improving the bending resistance of the second connection part near the welding area, thereby further ensuring the overall structural strength of the connecting piece and the electrode after welding and the long-term safety of the battery cell. And / or, limiting W to the range of 0.3 mm to 1.2 mm can ensure that the reinforcing ribs are processed and formed smoothly, avoid edge defects, and allow the reinforcing effect of the reinforcing ribs on the second connection to cover the edge area, improve the deformation resistance of the connecting piece in the overall plane, and further ensure the stability and safety of the internal structure of the battery cell.

[0018] In one optional embodiment, the second connecting portion includes a second transition region and a tab connecting region. The second transition region connects the first transition region and the tab connecting region. The tab connecting region is provided with one or multiple tabs spaced apart along the Y direction. Each tab connecting region is provided with at least one reinforcing rib.

[0019] Beneficial effects: Setting reinforcing ribs at least in the tab connection area can improve the structural strength of the tab connection area and prevent bending of the tab connection area under the tensile force of the tab after welding to the tab.

[0020] In one optional embodiment, there are multiple electrode connection areas, and a spacer groove is provided between two adjacent electrode connection areas. The spacer groove extends along the X direction to between two adjacent reinforcing ribs along the Y direction.

[0021] Beneficial effects: By setting a gap groove in the connection area of ​​two adjacent tabs, the vibration generated during the welding process is prevented from affecting each other between the two tab connection areas, thereby ensuring the welding quality and improving the reliability of the connection between the connecting piece and the tab. At the same time, by setting the gap groove to extend along the X direction to between two adjacent reinforcing ribs along the Y direction, that is, the end of the gap groove near the first connection part is located between the two reinforcing ribs, the deformation and collapse of the connecting piece at the end of the gap groove can be prevented, further improving the reliability of the connecting piece.

[0022] Secondly, this utility model also provides a battery pack, including the aforementioned battery cell. Since the battery pack includes the battery cell and has the same effects as the battery cell, it will not be described in detail here. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present utility model; Figure 2 for Figure 1 A top view of the battery cell shown; Figure 3 for Figure 2 A cross-sectional view along the AA direction; Figure 4 for Figure 3 A magnified view of part of E in the diagram; Figure 5 for Figure 2 Cross-sectional view along the BB direction; Figure 6 for Figure 5 A magnified view of part of F; Figure 7 for Figure 2 A cross-sectional view along the CC direction; Figure 8 for Figure 2 A cross-sectional view along the DD direction; Figure 9 for Figure 8 A magnified view of a portion of G; Figure 10 This is a schematic diagram of the connection state of the electrode assembly and the connecting piece inside the housing according to an embodiment of the present utility model; Figure 11 for Figure 10 A top view showing the connection state of the pole group and connecting piece inside the housing; Figure 12 for Figure 11 A magnified view of part of J; Figure 13 This is a schematic diagram of the structure after the connecting piece and the electrode tab are welded together; Figure 14 This is a schematic diagram of the structure of a connecting piece in a bent state according to an embodiment of the present utility model; Figure 15 for Figure 14 The top view of the connecting piece shown; Figure 16 for Figure 14 The front view of the connecting piece is shown; Figure 17 for Figure 15 A cross-sectional view along the KK direction; Figure 18 This is a schematic diagram of the structure of a connecting piece in an unfolded state according to an embodiment of the present utility model.

[0025] Explanation of reference numerals in the attached figures: 1. Shell; 2. Cover plate body; 3. Pole post; 4. Pole assembly; 41. Pole lug; 411. Extension; 412. Welding part; 42. Pole assembly body; 5. Connecting piece; 51. First connecting part; 511. Pole post connecting area; 512. First transition area; 513. Bending area; 52. Second connecting part; 521. Reinforcing rib; 522. Second transition area; 523. Pole lug connecting area; 524. Spacing groove; 6. First plastic part; 61. Blocking area. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] The battery includes components such as a casing, electrode assembly, cover plate, and connecting tabs. The electrode assembly is placed inside the casing, and the cover plate covers the open end of the casing. The electrode assembly and the cover plate are electrically connected through connecting tabs. Part of the connecting tab is welded to the tabs of the electrode assembly, while another part of the connecting tab is welded to the terminal post on the cover plate, thus allowing the battery's electrical energy to be led out to the outside through the connecting tab. The connecting tab typically includes a first connecting part located below the terminal post and a second connecting part corresponding to the tab. During cell assembly, the connecting tab is usually welded to the tab first through the second connecting part, then welded to the terminal post through a part of the first connecting part, and finally the first connecting part is bent so that the cover plate assembly folds over the electrode assembly. The connecting tab is set in a bent state inside the casing, and the bent connecting tab occupies a large space along the height direction (Z direction) of the cell. Traditionally, the second connection part of a connecting piece is usually lower than the first connection part, or the second connection part is flush with the first connection part. However, for a certain type of battery cell, the size of its tab along the Z direction is a fixed value. In order to ensure that the connecting piece is stably connected to the tab and the terminal respectively, the electrode assembly body needs to maintain a large distance from the terminal, which results in low space utilization inside the casing and is not conducive to improving the capacity and energy density of the battery cell.

[0028] The following is combined Figures 1 to 18 The following describes embodiments of the present invention.

[0029] According to an embodiment of the present invention, a battery cell is provided, comprising: a housing 1, a cover plate assembly, an electrode group 4, and a connecting piece 5. The housing 1 has an open end; the cover plate assembly covers the open end of the housing 1, and the cover plate assembly includes a cover plate body 2 and an electrode post 3 disposed on the cover plate body 2; the electrode group 4 is disposed in the inner cavity of the housing 1, and the electrode group 4 includes an electrode group body 42 and an electrode tab 41, the electrode tab 41 being connected to the side of the electrode group body 42 facing the cover plate body 2, and the dimension of the electrode tab 41 along the Z direction is H; the connecting piece 5 is disposed between the cover plate assembly and the electrode group 4, and the connecting piece 5 includes a first connecting portion 51 and a second connecting portion 52, the first connecting portion 51 including an electrode post connecting area 511 and a first connecting portion 52. The transition region 512 and the pole connection region 511 are electrically connected to the pole 3. The first transition region 512 is located below the pole connection region 511. The second connection part 52 is connected to one side of the first transition region 512 along the X direction and is electrically connected to the tab 41. The second connection part 52 protrudes upward relative to the first transition region 512. The distance between the upper surface of the second connection part 52 and the upper surface of the first transition region 512 along the Z direction is h1. The relationship between h1 and H is: 0.2≤h1 / H≤0.45. The units of h1 and H are both mm.

[0030] It should be noted that a battery cell has three perpendicular directions: X, Y, and Z. These directions form a Cartesian coordinate system, where the X direction refers to... Figures 1 to 6 , Figures 10 to 13 The direction indicated by the middle arrow ("X") is the direction of the Y direction. Figures 1 to 2 , Figures 7 to 13 The direction indicated by the middle arrow (Y) is the same as the direction indicated by the Z arrow (Z). Figure 1 , Figures 3 to 10 , Figure 13 The direction indicated by the middle arrow is "Z"; the up and down direction is parallel to the Z direction; "below" refers to the area below the Z direction, that is, the direction from the cover plate body 2 to the pole body 42 along the Z direction; "upward protrusion" refers to the upward protrusion along the Z direction, that is, the protrusion towards the cover plate body 2; "upper surface" refers to the upper surface in the Z direction, that is, the surface facing the direction of the cover plate body 2.

[0031] It should be noted that the tab 41 on the electrode assembly 4 extends upward relative to the electrode assembly body 42 along the Z direction. The tab 41 includes an extension 411 and a welding part 412. The extension 411 extends along the Z direction and passes upward through the second connecting part 52 from the lower side of the second connecting part 52. The welding part 412 bends relative to the extension 411 toward the upper surface of the second connecting part 52 and is electrically connected to the second connecting part 52. The dimension of the extension 411 along the Z direction is fixed, that is, the dimension H of the tab 41 along the Z direction is a fixed value that fluctuates within a small range. In addition, the distance between the pole post connection area 511 and the first transition area 512 of the first connecting part 51 along the Z direction is also a fixed value. This is prior art and will not be described in detail here.

[0032] It should also be noted that the first transition region 512 is located below the electrode connection region 511, that is, the first transition region 512 is the part of the first connection portion 51 closest to the electrode assembly body 42; h1 is the distance along the Z direction between the upper surface of the second connection portion 52 and the upper surface of the first transition region 512, that is, the upward protrusion of the second connection portion 52 relative to the first transition region 512. If h1 / H is less than 0.2, then the upward protrusion of the second connection portion 52 relative to the first transition region 512 is too small relative to the Z-direction dimension of the electrode tab 41, resulting in overutilization of the space above the cell (i.e., the space near the cover plate body 2). If the ratio of h1 / H is too small, it cannot effectively improve the utilization rate of the internal space of the battery cell. If h1 / H is greater than 0.45, the upward protrusion of the second connection part 52 relative to the first transition area 512 is too large relative to the Z-direction dimension of the electrode tab 41. On the one hand, this weakens the relative stability between the second connection part 52 and the first transition area 512, causing the connecting piece 5 to bend and deform easily, puncturing the first plastic part 6 or the electrode group body 42, affecting the safety of the battery cell. On the other hand, it will cause the first transition area 512 to be too close to the electrode group body 42, which can easily crush the electrode group body 42 or even cause a short circuit with the electrode group body 42, which will also affect the safety of the battery cell.

[0033] The battery cell of this embodiment has a first connecting portion 51 connected to the terminal post and a second connecting portion 52 connected to the tab 41. The second connecting portion 52 protrudes towards the cover plate body 2 relative to the first transition area 512 of the first connecting portion 51, that is, the second connecting portion 52 is located above the first transition area 512, so that the first connecting portion 51 and the second connecting portion 52 are set as a stepped structure. The second connecting portion 52 occupies the upper space of the battery cell near the cover plate assembly in the Z direction. When the size of the tab 41 in the Z direction is fixed. By reducing the distance between the electrode assembly body 42 and the cover plate body 2 along the Z direction, the size of the electrode assembly body 42 along the Z direction can be increased, thereby increasing the cell capacity and energy density. At the same time, by limiting the ratio h1 / H between the distance h1 of the second connecting part 52 protruding relative to the first transition area 512 and the size H of the electrode tab 41 along the Z direction to a value in the range of 0.2 to 0.45, the utilization rate of the upper space of the cell can be effectively improved, meeting the market demand for high-capacity cells, while ensuring the structural stability of the connecting piece 5 and the safety of the cell in use.

[0034] In one embodiment, the first connecting part 51 is welded to the electrode group 4 through the pole connecting area 511, and the second connecting part 52 is welded to the electrode tab 41.

[0035] In one embodiment, further combination Figure 4 As shown, the value range of the dimension H of the tab 41 along the Z direction is: 2.5mm≤H≤4.0mm. It should be noted that the tab 41 on the electrode group 4 is a whole formed by several electrode tabs being gathered together. The tab 41 extends upward and is bent and welded to the second connecting part 52. If H is less than 2.5mm, the dimension of the tab 41 along the Z direction is too small, the extension length of the tab 41 is insufficient, it is not convenient to bend, and it will cause the connecting piece 5 to be too close to the electrode group body 42, which has the risk of damaging the electrode group body 42 or short-circuiting with the electrode group body 42. If H is greater than 4.0mm, the dimension of the tab 41 along the Z direction is too large, which will increase the space occupied by the tab 41 inside the housing 1, which is not conducive to increasing the capacity of the cell. At the same time, the tab 41 may be too long and may be bent or broken during assembly or use. Therefore, by limiting H to a value within the range of 2.5 mm to 4.0 mm, the bending operation requirements of the tab 41 can be met, and the connection piece 5 can be prevented from damaging the electrode body 42 or short-circuiting with the electrode body 42. At the same time, the space waste and structural stability problems caused by the excessive size of the tab 41 can be avoided, thereby improving the utilization rate of the internal space of the casing while ensuring the reliability of the battery cell assembly.

[0036] Optionally, the value of H is any one of 2.5 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.5 mm, 3.7 mm, 4.0 mm, or a value between any two of these values.

[0037] In one embodiment, the distance h1 between the upper surface of the second connecting portion 52 and the upper surface of the first transition region 512 along the Z direction ranges from 0.35 mm to 1.2 mm. It should be noted that the upper surface of the second connecting portion 52 refers to the upper surface of the second connecting portion 52 along the Z direction, and the upper surface of the first transition region 512 refers to the upper surface of the first transition region 512 along the Z direction. If h1 is less than 0.35 mm, the upward protrusion of the second connecting portion 52 relative to the first transition region 512 is too small, resulting in insufficient utilization of the upper space of the battery cell by the connecting piece 5, and failing to effectively improve the internal space utilization rate of the battery cell. If h1 is greater than 1.2 mm, the upward protrusion of the second connecting portion 52 relative to the first transition region 512 is too large, resulting in poor structural stability of the connecting piece 5, and causing the first transition region 512 to be too close to the electrode assembly body 42, easily damaging the electrode assembly body 42 or causing a short circuit with the electrode assembly body 42. Therefore, by limiting h1 to a value within the range of 0.35 mm to 1.2 mm, the space utilization rate of the battery cell along the Z direction can be effectively improved, while ensuring the structural stability of the connecting piece 5 and the safety of the battery cell in use.

[0038] Optionally, the value of h1 is any one of 0.35 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, or a value between any two values.

[0039] In one embodiment, the distance along the Z direction between the lower surface of the second connecting portion 52 and the upper surface of the pole assembly body 42 is h2, where 2.35 mm ≤ h2 ≤ 3.2 mm. It should be noted that the lower surface refers to the lower surface along the Z direction, that is, the lower surface of the second connecting portion 52 is the surface of the second connecting portion 52 facing the pole assembly body 42; the upper surface refers to the upper surface along the Z direction, that is, the upper surface of the pole assembly body 42 is the surface of the pole assembly body 42 facing the cover plate body 2. If h2 is less than 2.35 mm, the distance between the second connecting part 52 and the electrode assembly body 42 is too small. During the assembly or use of the battery cell, the second connecting part 52 is likely to come into contact with the electrode assembly body 42, which may cause the electrode assembly body 42 to be damaged or even cause a short circuit in the positive and negative electrode plates inside the electrode assembly body 42, seriously affecting the safety and service life of the battery cell. If h2 is greater than 3.2 mm, the distance between the second connecting part 52 and the electrode assembly body 42 is too large, which will make the size of the electrode assembly body 42 in the Z direction too small, which cannot effectively improve the space utilization of the battery cell and is not conducive to the improvement of battery cell capacity and energy density.

[0040] Therefore, by limiting h2 to the range of 2.35 mm to 3.2 mm, it is possible to ensure that a safe distance is maintained between the second connection part 52 and the electrode assembly body 42, avoiding safety hazards caused by excessive spacing, and at the same time, to minimize the ineffective space between the electrode assembly body 42 and the cover plate assembly under the premise of ensuring safety, thereby providing favorable conditions for increasing the size of the electrode assembly body 42, and thus achieving an increase in cell capacity and energy density.

[0041] Optionally, the value of h2 is any one of 2.35 mm, 2.5 mm, 2.7 mm, 2.9 mm, 3.0 mm, 3.1 mm, 3.2 mm, or a value between any two of them.

[0042] In one embodiment, the cover plate body further includes: a first plastic part 6, the first plastic part 6 being disposed on the side of the cover plate body 2 facing the electrode group 4, the first plastic part 6 including a blocking area 61, the blocking area 61 being located between the cover plate body 2 and the electrode tab 41, the distance between the upper surface of the second connecting part 52 and the lower surface of the blocking area 61 along the Z direction being h3, wherein 0.15 mm≤h3≤0.6 mm. It should be noted that the first plastic part 6 has abutment portions at at least both ends along the X direction. The abutment portions abut against the electrode assembly body 42, thereby abutting the first plastic part 6 between the electrode assembly body 42 and the cover plate body 2, ensuring the fixation of the electrode assembly body 42 and ensuring the insulation between the electrode assembly body 42 and the cover plate body 2. The blocking area 61 is a part of the first plastic part 6 and is spaced apart from the abutment portions. The size of the blocking area 61 along the Z direction is smaller than the size of the abutment portions along the Z direction. The blocking area 61 and the electrode assembly body 42 are spaced apart along the Z direction, thereby providing clearance space for the installation of the electrode tab 41 and the connecting piece 5.

[0043] It should also be noted that the upper surface of the second connecting part 52 refers to the surface of the second connecting part 52 facing the cover plate body 2 along the Z direction, and the lower surface of the blocking area 61 refers to the surface of the blocking area 61 away from the cover plate body 2 along the Z direction. h3 is the distance between the second connecting part 52 and the blocking area 61. The welding part 412 of the electrode tab 41 is located between the second connecting part 52 and the blocking area 61. If h3 is less than 0.15 mm, the distance between the second connecting part 52 and the blocking area 61 is too small, and the electrode tab 41 may interfere with the blocking area 61, or even damage the first plastic part 6 and destroy the insulation performance of the first plastic part 6. If h3 is greater than 0.6 mm, the distance between the second connecting part 52 and the blocking area 61 is too large, which will increase the ineffective occupation of the upper space of the battery cell and is not conducive to improving the space utilization rate of the battery cell. Therefore, by limiting h3 to the range of 0.15 mm to 0.6 mm, interference between the welding part 412 of the tab 41 and the first plastic part 6 can be avoided, and the upper space of the battery cell can be effectively utilized to further improve the space utilization rate of the battery cell.

[0044] Optionally, the value of h3 is any one of 0.15 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, or a value between any two of these values.

[0045] In one embodiment, the distance along the Z direction between the lower surface of the first transition region 512 and the upper surface of the pole body 42 is h4, wherein 1.2 mm ≤ h4 ≤ 1.8 mm. It should be noted that the lower surface of the first transition region 512 refers to the surface of the first transition region 512 facing away from the cover plate body 2 along the Z direction. The first transition region 512 is located on the side of the pole connection area 511 facing away from the cover plate body 2. Therefore, the lower surface of the first transition region 512 is the lower surface of the entire first connection part 51. If h4 is less than 1.2 mm, the first transition region 512 is too close to the pole group body 42. When the cell is subjected to vibration or impact, the first transition region 512 is likely to come into contact with the pole group body 42, which may damage the surface insulation film or internal electrode of the pole group body 42, leading to an increased risk of internal short circuit. If h4 is greater than 1.8 mm, the distance between the first transition region 512 and the pole group body 42 is too large, which will compress the size of the pole group body 42 along the Z direction, which is not conducive to increasing the capacity of the cell.

[0046] Therefore, by limiting h4 to the range of 1.2 mm to 1.8 mm, sufficient structural clearance space can be provided for the first transition region 512 to prevent it from directly contacting the electrode assembly body 42 and causing safety issues. At the same time, the space utilization rate along the Z direction inside the housing can be improved, providing conditions for maximizing the size of the electrode assembly body 42, thereby balancing the safety and energy density requirements of the battery cell.

[0047] Optionally, the value of h4 is any one of 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, or a value between any two of these values.

[0048] In one embodiment, further combination Figures 14 to 18 As shown, the first connecting portion 51 further includes a bending region 513, which connects the pole connecting region 511 and the first transition region 512. It should be noted that the connecting piece 5 has the following characteristics: Figures 14 to 17 The bending state shown, and Figure 18 The unfolded state is shown; during the cell assembly process, the connecting piece 5 is welded to the electrode tab 41 via the second connecting part 52 in the unfolded state (as shown). Figure 13As shown), after being welded to the electrode post 3 via the first connecting part 51, the connecting piece 5 is then bent at the bending area 513, causing it to switch to a bent state. The electrode post connecting area 511 is located above the first transition area 512, so that the electrode post connecting area 511 and the first transition area 512 are spaced apart along the Z direction. By setting the bending area 513 between the electrode post connecting area 511 and the first transition area 512, it is easy to achieve the first folding of the electrode post connecting area 511 and the first transition area 512, thereby ensuring a smooth switch of the connecting piece from the unfolded state to the bent state and ensuring the smooth progress of the cell assembly process.

[0049] In one embodiment, along the X direction, the size of the bending region 513 is smaller than the size of the pole connection region 511 and the size of the first transition region 512, so that the connecting piece 5 can be bent from the bending region 513. Preferably, a through hole is provided on the bending region 513 to further ensure the smooth bending of the bending region 513.

[0050] In one embodiment, a reinforcing rib 521 is provided on the second connecting portion 52, and the orthographic projection of the tab 41 on the second connecting portion 52 along the Z direction is spaced apart from the reinforcing rib 521. The second connecting portion 52 is used for welding with the tab 41. By providing the reinforcing rib 521 on the second connecting portion 52, it is ensured that after the connecting piece 5 is welded to the tab 41, the connecting piece 5 can still maintain a flat state after being subjected to the tensile force of the tab, avoiding bending of the connecting piece 5 and puncturing the diaphragm, thus ensuring the safety of the battery cell. At the same time, by setting the orthographic projection of the tab 41 on the second connecting portion 52 along the Z direction to be spaced apart from the reinforcing rib 521, it is ensured that the area on the second connecting portion 52 where the tab 41 is welded is a plane, thereby ensuring the welding quality between the tab 41 and the second connecting portion 52, and avoiding the influence of welding on the reinforcing rib 521, thus ensuring the effective strengthening effect of the reinforcing rib 521 on the second connecting portion 52.

[0051] In one embodiment, further combination Figure 4 and Figure 16 , Figure 17As shown, the reinforcing rib 521 is formed by a portion of the second connecting part 52 protruding downwards, and the protrusion height of the reinforcing rib 521 is h5, and the thickness of the second connecting part 52 along the Z direction is h0; wherein, h5 and h0 satisfy the relationship: 0.8≤h5 / h0≤1.5, and the units of h5 and h0 are both mm. It should be noted that the downward protrusion refers to the downward protrusion along the Z direction, that is, the reinforcing rib 521 is formed by a portion of the second connecting part 52 protruding along the Z direction towards the pole body 42; the area of ​​the second connecting part 52 without the reinforcing rib 521 is the body area, and h5 is the downward protrusion distance of the reinforcing rib 521 relative to the body area of ​​the second connecting part 52, that is, the distance along the Z direction between the lower surface of the reinforcing rib 521 and the lower surface of the body area of ​​the second connecting part 52. If h5 / h0 is less than 0.8, the protrusion height of the reinforcing rib 521 is insufficient, and the structural reinforcement effect of the second connecting part 52 is not obvious. The connecting piece 5 may still bend and deform when subjected to the tensile force of the pole lug 41. If h5 / h0 is greater than 1.5, the protrusion height of the reinforcing rib 521 is too large, and the reinforcing rib 521 is difficult to process and form. Even if it can be processed and formed, it will be too close to the pole body 42, which poses a risk of interference with the pole body 42.

[0052] Therefore, by setting the reinforcing rib 521 to protrude downwards, the space between the second connecting part 52 and the electrode group body 42 is fully utilized. The ratio between the protrusion height of the reinforcing rib 521 and the thickness of the body area of ​​the second connecting part 52 is in the range of 0.8 to 1.5. This can effectively improve the structural strength of the second connecting part 52, prevent the connecting piece 5 from bending or deforming when subjected to the continuous tensile force of the electrode tab 41, thereby avoiding the safety hazard of the connecting piece 5 possibly puncturing the diaphragm after bending. It can also ensure the processing feasibility of the reinforcing rib 521 and avoid interference between the reinforcing rib 521 and the electrode group body 42, thus ensuring the stability of the internal structure of the battery cell.

[0053] Optionally, the value of h5 / h0 is any one of 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 or a value between any two values.

[0054] In one embodiment, the value of h0 ranges from 0.4 mm to 1.0 mm. If h0 is less than 0.4 mm, the second connecting portion 52 is too thin, and the overall structural strength of the connecting piece 5 is insufficient. It is prone to breakage or excessive deformation during welding with the tab 41 and subsequent bending, affecting the reliability of the connection. If h0 is greater than 1.0 mm, the material cost of the connecting piece 5 increases, and it occupies too much internal space in the housing, which is not conducive to improving the energy density of the battery cell. Therefore, limiting h0 to the range of 0.4 mm to 1.0 mm can ensure that the connecting piece 5 has sufficient structural strength to meet the requirements of welding and assembly processes, while also controlling its own thickness and space occupation, thus achieving a balance between material cost and battery cell performance.

[0055] Optionally, the value of h0 is any one of 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, or a value between any two of these values.

[0056] In one embodiment, the thickness of the pole connection area 511, the first transition area 512, and the bending area 513 on the first connection portion 51 is equal to the thickness of the body area of ​​the second connection portion 52, which is h0.

[0057] In one embodiment, the distance between the orthographic projection of the tab 41 along the Z direction onto the second connecting portion 52 and the distance between the reinforcing rib 521 along the X direction is L, where 0.5 mm ≤ L ≤ 5.0 mm. It should be noted that the area where the tab 41 is welded to the second connecting portion 52 is within the orthographic projection range of the tab 41 along the Z direction onto the second connecting portion 52. If L is less than 0.5 mm, the distance between the welding area of ​​the tab 41 and the reinforcing rib 521 is too close, and the heat generated during welding may be conducted to the reinforcing rib 521, causing thermal deformation of the metal material near the reinforcing rib 521, affecting the structural stability of the reinforcing rib 521, and weakening its reinforcing effect on the second connecting portion 52. If L is greater than 5.0 mm, the distance between the welding area of ​​the tab 41 and the reinforcing rib 521 is too large, so that the reinforcing range of the reinforcing rib 521 on the second connecting portion 52 fails to effectively cover the stress concentration area near the welding area. When the tab 41 is subjected to tensile force, the second connecting portion 52 may still bend and deform near the welding area, failing to fully utilize the structural reinforcing effect of the reinforcing rib 521.

[0058] Therefore, by limiting L to the range of 0.5 mm to 5.0 mm, the heat during the welding process of the tab 41 can be avoided from affecting the reinforcing rib 521, ensuring the structural stability of the reinforcing rib 521. At the same time, the reinforcing effect of the reinforcing rib 521 can be extended to the key stress-bearing parts around the welding area, significantly improving the bending resistance of the second connection part 52 near the welding area. This further ensures the overall structural strength of the connecting piece 5 after welding with the tab 41 and the long-term safety of the battery cell.

[0059] Optionally, the value of L is any one of 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, or a value between any two of these values.

[0060] In one embodiment, the distance between the reinforcing rib 521 and the edge of the second connecting portion 52 along the Y direction is W, where 0.3 mm ≤ W ≤ 1.2 mm. If W is less than 0.3 mm, the reinforcing rib 521 is too close to the edge of the second connecting portion 52, which is not conducive to the processing and forming of the reinforcing rib 521 and may scratch surrounding components during assembly or use. If W is greater than 1.2 mm, the reinforcing rib 521 is positioned too close to the center of the second connecting portion 52, resulting in a lack of effective reinforcement in the area near the edge of the second connecting portion 52. This makes the edge area of ​​the connecting piece 5 prone to bending, reducing the overall structural stability of the connecting piece 5. Therefore, limiting W to the range of 0.3 mm to 1.2 mm can ensure that the reinforcing rib 521 can be smoothly processed and formed, avoiding edge defects, and also allow the reinforcing effect of the reinforcing rib 521 on the second connecting portion 52 to cover the edge area, improving the deformation resistance of the connecting piece 5 in the overall plane and further ensuring the stability and safety of the internal structure of the battery cell.

[0061] Optionally, the value of W is any one of 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, or a value between any two of these values.

[0062] In one embodiment, the second connecting portion 52 includes a second transition region 522 and a tab connecting region 523, the boundary line between the second transition region 522 and the tab connecting region 523 being as follows: Figure 15As shown by the dashed line, the second transition zone 522 connects the first transition zone 512 and the tab connection zone 523. The tab connection zone 523 has one location or multiple locations spaced along the Y direction, and each tab connection zone 523 has at least one reinforcing rib 521. It should be noted that the tab connection zone 523 is used for welding with the tab 41. Therefore, providing reinforcing ribs 521 corresponding to at least one tab connection zone 523 can improve the structural strength of the tab connection zone 523 and prevent bending under the tensile force of the tab after welding.

[0063] In one embodiment, further combination Figures 14 to 15 As shown, there are multiple tab connection areas 523. A spacer groove 524 is provided between two adjacent tab connection areas 523, extending along the X direction to between two adjacent reinforcing ribs 521 along the Y direction. Each tab connection area 523 is welded to one tab 41. By providing a spacer groove 524 between two adjacent tab connection areas 523, vibrations generated during welding are prevented from affecting each other between the two tab connection areas 523, thus ensuring welding quality and improving the reliability of the connection between the connecting piece 5 and the tab 41. Simultaneously, by extending the spacer groove 524 along the X direction to between two adjacent reinforcing ribs 521 along the Y direction, i.e., the end of the spacer groove 524 near the first connecting part 51 is located between two reinforcing ribs 521, deformation and collapse of the connecting piece 5 at the end of the spacer groove 524 can be prevented, further improving the reliability of the connecting piece 5.

[0064] It should be noted that the dimension of the spacer groove 524 along the X direction is equal to the dimension of the tab connection area 523 along the X direction. Therefore, the reinforcing rib 521 is straddling the tab connection area 523 and the second transition area 522. That is, part of the reinforcing rib 521 is located in the tab connection area 523 and another part is located in the second transition area 522. This can simultaneously strengthen the structural strength of the tab connection area 523 and the second transition area 522, and further improve the reliability of the connecting piece 5.

[0065] In one embodiment, the spacer groove 524 is a through groove extending along the thickness direction (i.e., the Z direction) of the second connecting portion 52, which facilitates processing and can minimize the mutual stiffness between two adjacent tab connecting areas 523. Preferably, the spacer groove 524 is U-shaped, and the side of the spacer groove 524 facing away from the first connecting portion 51 along the X direction is the U-shaped opening side.

[0066] In one embodiment, the reinforcing rib 521 is racetrack-shaped. The orthographic projection of the reinforcing rib 521 along the Z-direction onto the surface of the second connection 52 is racetrack-shaped. The arc transition structure of the reinforcing rib 521 with the racetrack-shaped design can effectively disperse stress concentration and avoid stress concentration problems at the corners of the reinforcing rib 521, thereby further improving the deformation resistance of the second connection 52 and ensuring that the reinforcing effect of the reinforcing rib 521 on the second connection 52 is more reliable.

[0067] According to an embodiment of the present invention, another aspect provides a battery pack, including the aforementioned battery cell. Optionally, the number of battery cells may be multiple. Optionally, the battery cell is a lithium-ion battery cell.

[0068] Unless otherwise stated, all parameters are tested at 25°C.

[0069] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: The shell has an open end; A cover plate assembly is provided to cover the opening end of the housing, the cover plate assembly including a cover plate body and an pole post disposed on the cover plate body; An electrode assembly is disposed in the inner cavity of the housing. The electrode assembly includes an electrode assembly body and an electrode tab. The electrode tab is connected to the side of the electrode assembly body facing the cover plate body. The dimension of the electrode tab along the Z direction is H. A connecting piece is disposed between the cover plate assembly and the electrode group. The connecting piece includes a first connecting portion and a second connecting portion. The first connecting portion includes an electrode post connecting area and a first transition area. The electrode post connecting area is electrically connected to the electrode post. The first transition area is located below the electrode post connecting area. The second connecting portion is connected to one side of the first transition area along the X direction and is electrically connected to the electrode tab. The second connecting portion protrudes upward relative to the first transition area. The distance between the upper surface of the second connecting portion and the upper surface of the first transition area along the Z direction is h1, wherein h1 and H satisfy the relationship: 0.2≤h1 / H≤0.

45.

2. The battery cell according to claim 1, characterized in that, The value range of the dimension H of the electrode tab along the Z direction is: 2.5 mm ≤ H ≤ 4.0 mm; And / or, the distance h1 between the upper surface of the second connecting part and the upper surface of the first transition area along the Z direction is in the range of 0.35 mm ≤ h1 ≤ 1.2 mm.

3. The battery cell according to claim 1, characterized in that, The distance along the Z direction between the lower surface of the second connecting part and the upper surface of the pole group body is h2, wherein 2.35 mm ≤ h2 ≤ 3.2 mm; And / or, the distance along the Z direction between the lower surface of the first transition region and the upper surface of the pole group body is h4, where 1.2 mm ≤ h4 ≤ 1.8 mm.

4. The battery cell according to claim 1, characterized in that, The cover plate body further includes: a first plastic part, the first plastic part being disposed on the side of the cover plate body facing the electrode assembly, the first plastic part including a blocking area, the blocking area being located between the cover plate body and the electrode tab, the distance along the Z direction between the upper surface of the second connecting part and the lower surface of the blocking area being h3, wherein 0.15 mm≤h3≤0.6 mm; And / or, the first connection portion further includes a bending region, the bending region being connected between the pole connection region and the first transition region.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The second connecting part is provided with a reinforcing rib, and the orthographic projection of the electrode tab along the Z direction on the second connecting part is spaced apart from the reinforcing rib.

6. The battery cell according to claim 5, characterized in that, The reinforcing rib is formed by a portion of the second connecting part protruding downwards, and the protrusion height of the reinforcing rib is h5, and the thickness of the second connecting part along the Z direction is h0. Among them, h5 and h0 satisfy the following relationship: 0.8≤h5 / h0≤1.5; and / or, the value range of h0 is: 0.4 mm≤h0≤1.0 mm.

7. The battery cell according to claim 5, characterized in that, The distance between the orthographic projection of the electrode tab along the Z direction onto the second connecting portion and the distance between the reinforcing rib along the X direction is L, wherein 0.5 mm ≤ L ≤ 5.0 mm; And / or, the distance between the reinforcing rib and the edge of the second connecting portion along the Y direction is W, wherein 0.3 mm ≤ W ≤ 1.2 mm.

8. The battery cell according to claim 7, characterized in that, The second connecting portion includes a second transition region and a tab connecting region. The second transition region connects the first transition region and the tab connecting region. The tab connecting region has one or multiple tabs spaced apart along the Y direction. Each tab connecting region has at least one reinforcing rib.

9. The battery cell according to claim 8, characterized in that, The number of electrode connection areas is multiple, and a spacer groove is provided between two adjacent electrode connection areas. The spacer groove extends along the X direction to between two adjacent reinforcing ribs along the Y direction.

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

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