Cover plate assembly and battery cell

Abstract

The invention relates to the technical field of batteries, and discloses a cover plate assembly and a battery cell. The cover plate assembly comprises: a cover plate body having a pole hole; the polar column comprises a bottom plate and a column body, the column body is arranged in the polar column hole in a penetrating manner, the bottom plate comprises a plate body and a boss, the plate body is connected with the column body, the plate body is located on the lower side of the cover plate body in the Z direction, and the boss is connected to the lower surface of the plate body in the Z direction; the connecting piece is arranged on the lower side of the plate body in the Z direction, a positioning hole is formed in the connecting piece, the connecting piece is arranged on the boss in a sleeving mode through the positioning hole, the boss protrudes out of the lower surface of the connecting piece in the Z direction, the boss is welded to the connecting piece to form a welding mark, and the welding mark is arranged in the circumferential direction of the positioning hole. The boss is sleeved with the connecting piece through the positioning hole, the boss protrudes out of the lower surface of the connecting piece, the stroke of the connecting piece when the connecting piece is assembled on the boss is increased, automatic deviation rectification and alignment can be achieved in the stroke of the connecting piece sleeved with the boss, the assembling yield is increased, side welding is convenient to adopt, and the welding yield is higher.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to cover plate assemblies and battery cells. Background Technology

[0002] The battery cell consists of a casing, electrode assembly, and cover plate assembly. The cover plate assembly covers the open end of the casing to form a sealed space for accommodating the electrode assembly. The cover plate assembly includes a cover plate body, terminals, and connecting tabs. The connecting tabs connect the tabs and terminals of the electrode assembly, and the tabs are transferred to the terminals via the connecting tabs, allowing the battery cell to charge and discharge through the external terminals. In existing technologies, the connecting tabs are assembled and welded to the base plate of the terminals. However, during the assembly process of the connecting tabs and terminals, if positioning errors occur, the connecting tabs and terminals cannot automatically correct their alignment, resulting in a certain percentage of misalignment during press-fitting. The connecting tabs are damaged by the protrusions, leading to poor assembly and welding problems between the connecting tabs and terminals, affecting the safety of the battery during subsequent use. Summary of the Invention

[0003] This invention provides a cover plate assembly and a battery cell to solve the problems of poor assembly and poor welding between the connecting piece and the electrode.

[0004] In a first aspect, the present invention provides a cover plate assembly, comprising: a cover plate body having an electrode post hole; an electrode post including a base plate and a post body, the post body being disposed in the electrode post hole, the base plate including a plate body and a boss, the plate body being connected to the post body, and the plate body being located on the lower side of the cover plate body along the Z direction, the boss being connected to the lower surface of the plate body along the Z direction; a connecting piece disposed on the lower side of the plate body along the Z direction, the connecting piece having a positioning hole, the connecting piece being sleeved on the boss through the positioning hole, the boss protruding from the lower surface of the connecting piece along the Z direction, the boss being welded to the connecting piece to form a weld mark, the weld mark being arranged circumferentially around the positioning hole.

[0005] Beneficial effects: By setting a downward-protruding boss on the base plate of the electrode post and opening positioning holes corresponding to the boss on the connecting piece, the connecting piece can be positioned and assembled with the electrode post by fitting it onto the boss through the positioning holes. Furthermore, by setting the dimension of the boss along the Z direction to be greater than the thickness of the connecting piece along the Z direction, and the boss protruding downwards from the lower surface of the connecting piece along the Z direction, the dimension of the boss along the Z direction is the sliding stroke of the connecting piece when assembling onto the boss, increasing the stroke of the connecting piece when assembling onto the boss. Even if there are positioning and installation errors in the automatic line equipment, automatic correction and alignment can be achieved during the stroke of the connecting piece fitting onto the boss, avoiding misalignment during pressing, thus avoiding damage to the connecting piece and the boss pad, improving the assembly yield. In addition, the downward-protruding structure of the boss facilitates side welding from the outer periphery of the boss to the connecting piece. Compared with traditional flat welding, side welding is easier to operate, has a higher welding yield, ensures the reliability of the battery cell during subsequent use, and improves the safety of the battery cell.

[0006] In one optional embodiment, the weld width of the portion of the solder mark located on the connecting piece in the XY plane is W1, wherein the value of W1 ranges from 0.8 mm to 3 mm. And / or, the portion of the solder mark located on the connecting piece has a penetration depth of H1 along the Z direction, wherein the value of H1 is in the range of 0.3 mm ≤ H1 ≤ 1.5 mm.

[0007] Beneficial effects: By limiting W1 to a value within the range of 0.8 mm to 3 mm, it can ensure that the part of the solder mark located on the connecting piece has sufficient welding strength, avoid welding failure and the connecting piece falling off, and also avoid excessive welding power and excessive design space occupation, thus avoiding waste of materials and energy and reducing production costs. And / or, by limiting H1 to a value within the range of 0.3 mm to 1.5 mm, it is possible to ensure that the portion of the solder mark located on the connecting piece has sufficient welding strength, avoiding welding failure and resulting in the connecting piece falling off, while also avoiding excessive welding power and excessive space occupation, thus avoiding waste of materials and energy and reducing production costs.

[0008] In one optional embodiment, the weld width of the portion of the solder mark located on the boss in the XY plane is W2, wherein the value of W2 ranges from 0.3 mm to 1.5 mm. And / or, the portion of the solder mark located on the boss has a penetration depth of H2 along the Z direction, wherein the value of H2 is in the range of 0.5 mm ≤ H2 ≤ 3 mm.

[0009] Beneficial effects: By limiting W2 to a value within the range of 0.3 mm to 1.5 mm, it is possible to ensure that the part of the solder mark located on the boss has sufficient welding strength, guarantee the connection strength, and avoid the solder mark failure leading to the detachment of the connecting piece. It is also possible to avoid excessive welding power and excessive design space occupation, thus avoiding waste of materials and energy and reducing production costs. And / or, by limiting H2 to a value within the range of 0.5 mm to 3 mm, it is possible to ensure that the portion of the solder mark located on the boss has sufficient welding strength, avoiding welding failure and resulting in the detachment of the connecting piece, while also avoiding excessive welding power and excessive space occupation, thus avoiding waste of materials and energy and reducing production costs.

[0010] In one optional embodiment, the lower edge of the boss along the Z direction is chamfered, and the distance between the chamfer and the solder mark along the Z direction is H3, wherein the value of H3 is in the range of 0.2 mm ≤ H3 ≤ 10 mm.

[0011] Beneficial effects: By setting the lower edge of the boss as a chamfer, the chamfer provides a guide for the assembly of the boss into the positioning hole, which facilitates the smooth assembly of the two and helps to improve the assembly yield. At the same time, by limiting the distance between the chamfer and the solder mark in the Z direction to a range of 0.2 mm to 10 mm, it is possible to avoid soldering explosions, ensure soldering quality, avoid material waste, and prevent the boss from occupying too much space inside the cell, thereby helping to improve the energy density of the cell.

[0012] In one optional embodiment, the distance along the Z direction between the lower surface of the boss and the lower surface of the connecting piece is H4, wherein the value of H4 is in the range of 2 mm ≤ H4 ≤ 10 mm. And / or, the thickness of the connecting piece along the Z direction is T, wherein the value of T is in the range of 0.5 mm ≤ T ≤ 3 mm.

[0013] Beneficial effects: By limiting H4 to a value within the range of 2 mm to 10 mm, the boss protrudes downwards by a reasonable size relative to the connecting piece. This provides sufficient space for side welding, ensuring smooth welding, improving welding efficiency and quality, while avoiding waste of materials and space, thus saving costs and increasing the energy density of the battery cell. And / or, by limiting T to a value within the range of 0.5 mm to 3 mm, it is possible to ensure that the connecting piece has sufficient structural strength, improve reliability, and provide sufficient space for welding, thereby ensuring welding quality, while also avoiding waste of materials and space, thus saving costs.

[0014] In one optional embodiment, the connecting piece includes a pole post connecting area and a tab connecting area connected along the X direction. The pole post connecting area is correspondingly disposed with the base plate, and the positioning hole is provided on the pole post connecting area. The upper surface of the pole post connecting area is attached to the lower surface of the plate body. The distance along the X direction between the tab connecting area and the solder mark is W3, wherein the value of W3 is in the range of 0.5 mm ≤ W3 ≤ 30 mm.

[0015] Beneficial effects: It can avoid welding explosions, ensure welding quality, and avoid wasting space and materials, thereby saving production costs.

[0016] In one optional embodiment, the distance between the wall of the positioning hole and the boss in the XY plane is g1, wherein the value of g1 is in the range of 0 mm ≤ g1 ≤ 1 mm.

[0017] Beneficial effects: Ensures smooth assembly of the boss on the pole and the positioning hole on the connecting piece, and avoids welding defects such as spalls during the welding process, thereby ensuring welding quality.

[0018] In one optional embodiment, the cover plate assembly further includes a sealing ring located on the upper side of the plate body along the Z direction and fitted onto the column body. The distance between the solder mark and the sealing ring along the Z direction is g2, wherein the value of g2 is in the range of 1.2 mm ≤ g2 ≤ 5 mm.

[0019] Beneficial effects: It can avoid excessive heat from welding being transferred to the sealing ring and burning it, thus preventing seal failure, ensuring the reliability of the seal between the terminal and the cover plate, improving safety, and also avoids excessively thick plates, avoiding material waste and excessive terminal weight, thereby saving costs and helping to improve the energy density of the battery cell.

[0020] In one alternative embodiment, the orthographic projection of the boss along the Z direction in the XY plane is circular, elliptical, or polygonal. And / or, the number of the bosses is one or more, and the number of the positioning holes is equal to the number of the bosses and corresponds one-to-one.

[0021] Beneficial effects: The shape of the boss can be selected according to the actual needs of the product. Circular and elliptical structures are simple and easy to process and form. Polygons themselves have positioning and anti-rotation functions, which can further improve the assembly yield of the connecting piece and the boss. And / or, the number of bosses can be flexibly selected. When there is only one boss, the structure is simple and easy to process. When there are two or more bosses, the positioning accuracy during the assembly process of the connecting piece and the pole post can be further improved, the assembly quality can be improved, and the welding quality between the connecting piece and the pole post can be further guaranteed.

[0022] Secondly, the present invention also provides a battery cell, comprising: a housing having an open end; an electrode assembly disposed within the inner cavity of the housing; and the aforementioned cover plate assembly covering the open end of the housing. Since the battery cell includes the cover plate assembly and has the same effect as the cover plate assembly, it will not be described in detail here. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a top view of a cover plate assembly according to an embodiment of the present invention; Figure 2 for Figure 1 A cross-sectional view along the AA direction; Figure 3 for Figure 2 A magnified view of part B in the diagram; Figure 4 for Figure 3 A magnified view of part of C; Figure 5 This is a bottom view of a cover plate assembly according to an embodiment of the present invention; Figure 6 This is a bottom view of another cover plate assembly according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a connecting piece according to an embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures: 1. Cover plate body; 11. Pole post hole; 2. Pole post; 21. Base plate; 211. Plate body; 212. Boss; 2121. Chamfer; 22. Column body; 3. Connecting piece; 31. Positioning hole; 301. Pole post connection area; 302. Pole lug connection area; 4. Weld mark; 5. Sealing ring; 6. Riveting block; 7. First plastic part; 8. Second plastic part. Detailed Implementation

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

[0027] The battery cell consists of a housing, electrode assembly, and cover plate assembly. The cover plate assembly covers the open end of the housing to form a sealed space for accommodating the electrode assembly. The cover plate assembly includes a cover plate body, terminals, and connecting pieces. The connecting pieces connect the tabs and terminals of the electrode assembly. The tabs are transferred to the terminals through the connecting pieces, so that the battery cell can be charged and discharged through the external terminals. The connecting piece is assembled and welded to the base plate of the terminal post. Existing technologies include a structure with positioning holes on the connecting piece and a boss at the lower end of the terminal post base plate. The connecting piece fits onto the boss through the positioning holes, thus achieving positioning and assembly between the connecting piece and the terminal post. However, the researchers of this application found that the connecting piece is usually quite thin, and the height of the boss is equal to the thickness of the connecting piece. During the assembly of the connecting piece and the terminal post base plate, the sliding stroke of the connecting piece into the boss is equal to the thickness of the connecting piece. When there is an error in the positioning and installation of the automated production line, the thin connecting piece results in insufficient sliding stroke, making it impossible to achieve automatic correction and alignment during the sliding process. This leads to a certain percentage of misalignment during press-fitting, causing the connecting piece to be damaged by the boss, resulting in poor welding and failure, affecting the safety of the battery during subsequent use. Furthermore, traditional methods use flat welding to weld the connecting piece to the boss on the terminal post base plate. Flat welding is prone to welding defects, affecting production efficiency and resulting in significant losses.

[0028] The following is combined Figures 1 to 7 The following describes embodiments of the present invention.

[0029] According to an embodiment of the present invention, a cover plate assembly is provided, comprising: a cover plate body 1, a pole post 2, and a connecting piece 3. The cover plate body 1 has a pole post hole 11; the pole post 2 includes a base plate 21 and a post 22, the post 22 is inserted into the pole post hole 11, the base plate 21 includes a plate 211 and a boss 212, the plate 211 is connected to the post 22, and the plate 211 is located on the lower side of the cover plate body 1 along the Z direction, the boss 212 is connected to the lower surface of the plate 211 along the Z direction; the connecting piece 3 is disposed on the lower side of the plate 211 along the Z direction, the upper surface of the connecting piece 3 is in contact with the lower surface of the plate 211, the connecting piece 3 has a positioning hole 31, the connecting piece 3 is sleeved on the boss 212 through the positioning hole 31, the size of the boss 212 along the Z direction is greater than the thickness of the connecting piece 3 along the Z direction, the boss 212 protrudes from the lower surface of the connecting piece 3 along the Z direction, the boss 212 is welded to the connecting piece 3 to form a weld mark 4, the weld mark 4 is arranged around the circumference of the positioning hole 31.

[0030] It should be noted that the Z direction refers to Figures 2 to 4The direction indicated by the middle arrow "Z" is specifically the thickness direction of the cover plate assembly. The cover plate body 1 has upper and lower sides arranged opposite to each other along the Z direction. When the cover plate assembly is assembled with the housing of the battery cell, the side of the cover plate body 1 facing away from the housing along the Z direction is the upper side, and the side of the cover plate body 1 facing the inner cavity of the housing along the Z direction is the lower side. The "lower surface" mentioned refers to the lower surface along the Z direction. The plate 211 and the connecting piece 3 are both located below the cover plate body 1. The lower surface of the plate 211 is the surface of the plate 211 facing away from the cover plate body 1 along the Z direction, and the lower surface of the connecting piece 3 is the surface of the connecting piece 3 facing away from the cover plate body 1 along the Z direction.

[0031] Using the cover plate assembly of this embodiment, by providing a downwardly protruding boss 212 on the base plate 21 of the pole post 2 and opening a positioning hole 31 corresponding to the boss 212 on the connecting piece 3, the connecting piece 3 can be positioned and assembled with the pole post 2 by fitting it onto the boss 212 through the positioning hole 31. Furthermore, by setting the dimension of the boss 212 in the Z direction to be greater than the thickness of the connecting piece 3 in the Z direction, and by making the boss 212 protrude downward from the lower surface of the connecting piece 3 in the Z direction, the dimension of the boss 212 in the Z direction is the sliding stroke of the connecting piece 3 when it is assembled onto the boss 212, thus increasing the... Even if there are positioning and installation errors in the automatic line equipment, the stroke of the connecting piece 3 when it is assembled onto the boss 212 can be automatically corrected and aligned during the stroke of the connecting piece 3 into the boss 212, avoiding misalignment during pressing and thus preventing damage to the connecting piece 3 and the boss 212, improving the assembly yield. Furthermore, the downward protrusion of the boss 212 onto the connecting piece 3 facilitates side welding from the outer periphery of the boss 212 to the connecting piece 3. Compared to traditional flat welding, side welding is easier to operate, has a higher welding yield, ensures the reliability of the battery cell during subsequent use, and improves the safety of the battery cell.

[0032] It should be noted that the pole post hole 11 is a through hole penetrating the cover plate body 1 along the Z direction, and the positioning hole 31 is a through hole penetrating the connecting piece 3 along the Z direction; the pole post 2 is integrally formed, and the plate body 211 is fixedly connected to the lower end of the post body 22, and the boss 212 is formed by a portion of the lower surface of the plate body 211 protruding downwards. The connecting piece 3 is positioned and assembled with the boss 212 on the pole post 2 through the positioning hole 31, and then the mating area is welded and fixed from the lower side of the connecting piece 3 along the welding trajectory. The welding trajectory is located between the outer peripheral surface of the boss 212 and the positioning hole 31, and surrounds the circumference of the positioning hole 31. After welding, a weld mark 4 is formed between the connecting piece 3 and the boss 212. The orthographic projection of the weld mark 4 along the Z direction in the XY plane is annular.

[0033] It should be noted that the cover plate assembly has intersecting X, Y, and Z directions, such as... Figures 1 to 6As shown, the X, Y, and Z directions form a rectangular coordinate system, and the intersection of the X and Y directions forms the XY plane; specifically, the X direction is the length direction of the cover plate assembly, the Y direction is the width direction of the cover plate assembly, and the Z direction is the thickness direction of the cover plate assembly.

[0034] In one embodiment, further combination Figure 4 As shown, the weld width of the portion of the solder mark 4 located on the connecting piece 3 in the XY plane is W1, where the value of W1 ranges from 0.8 mm to 3 mm. It should be noted that part of the solder mark 4 is located on the connecting piece 3, and another part is located on the boss 212, thus achieving a fixed connection between the boss 212 and the connecting piece 3 through the solder mark 4. The orthographic projection of the portion of the solder mark 4 on the connecting piece 3 along the Z direction in the XY plane is annular, and the width of this annular ring in the XY plane is W1. If W1 is less than 0.8 mm, the weld width is too small, resulting in insufficient welding strength. During subsequent use of the battery cell, welding failure is likely, and the connecting piece 3 may easily detach due to insufficient connection strength. If W1 is greater than 3 mm, the weld width is too large, requiring excessive welding power and occupying too much design space, wasting materials and energy. Therefore, by limiting W1 to a value within the range of 0.8 mm to 3 mm, it is possible to ensure that the portion of the solder mark 4 located on the connecting piece 3 has sufficient welding strength, thus avoiding welding failure and causing the connecting piece 3 to fall off. It is also possible to avoid excessive welding power and excessive space occupation, thus avoiding waste of materials and energy and reducing production costs.

[0035] Optionally, the value of W1 is any one of 0.8 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, or a value between any two of these values.

[0036] In one embodiment, further combination Figure 4 As shown, the penetration depth of the weld mark 4 on the connecting piece 3 along the Z direction is H1, where the value of H1 ranges from 0.3 mm to 1.5 mm. If H1 is less than 0.3 mm, the penetration depth of the weld mark 4 on the connecting piece 3 is too small, resulting in insufficient welding strength and a high risk of welding failure. The connecting piece 3 is prone to detachment due to insufficient connection strength. If H1 is greater than 1.5 mm, the penetration depth of the weld mark 4 on the connecting piece 3 is too large, requiring excessive welding power and occupying too much design space, thus wasting materials and energy. Therefore, by limiting H1 to the range of 0.3 mm to 1.5 mm, it is possible to ensure that the portion of the weld mark 4 on the connecting piece 3 has sufficient welding strength, preventing welding failure and detachment of the connecting piece 3, while also avoiding excessive welding power and excessive design space occupation, thus avoiding waste of materials and energy and reducing production costs.

[0037] Optionally, the value of H1 is any one of 0.3 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, or a value between any two of these values.

[0038] In one embodiment, further combination Figure 4 As shown, the weld width of the portion of solder mark 4 located on boss 212 in the XY plane is W2, where the value of W2 ranges from 0.3 mm to 1.5 mm. The orthographic projection of the portion of solder mark 4 located on boss 212 along the Z direction in the XY plane is annular, and the width of this annular ring in the XY plane is W2. If W2 is less than 0.3 mm, the weld width of solder mark 4 on boss 212 is too small, resulting in insufficient welding strength. During the use of the battery cell, solder mark 4 is prone to breakage due to insufficient welding strength, which in turn leads to the detachment of the connecting piece 3. If W2 is greater than 1.5 mm, the weld width of solder mark 4 on boss 212 is too large, requiring excessive welding power and occupying too much design space, wasting materials and energy. Therefore, by limiting W2 to a value within the range of 0.3 mm to 1.5 mm, it is possible to ensure that the portion of the solder mark 4 located on the boss 212 has sufficient welding strength, guarantee the connection strength, and prevent the solder mark 4 from failing and causing the connecting piece 3 to fall off. At the same time, it is possible to avoid excessive welding power and excessive space occupation, thus avoiding waste of materials and energy and reducing production costs.

[0039] Optionally, the value of W2 is any one of 0.3 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, or a value between any two of these values.

[0040] In one embodiment, further combination Figure 4 As shown, the penetration depth of the weld mark 4 on the boss 212 along the Z direction is H2, where the value of H2 ranges from 0.5 mm to 3 mm. Similarly, by limiting H2 to the range of 0.5 mm to 3 mm, it is possible to ensure that the portion of the weld mark 4 on the boss 212 has sufficient welding strength, avoiding welding failure that could cause the connecting piece 3 to detach, while also avoiding excessive welding power and excessive space occupation, thus avoiding waste of materials and energy and reducing production costs.

[0041] Optionally, the value of H2 is any one of 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, or a value between any two of these values.

[0042] In one embodiment, when the connecting piece 3 is welded to the boss 212, the welding is performed from the lower side of the connecting piece 3, and the weld mark 4 extends obliquely upward, so that the penetration depth H2 of the weld mark 4 on the boss 212 is greater than the penetration depth H1 of the weld mark 4 on the connecting piece 3. Here, obliquely upward refers to the direction that is at an angle to the Z direction and is biased towards the center line of the positioning hole 31 from the lower right to the upper right.

[0043] In one embodiment, further combination Figure 4 As shown, the lower edge of the boss 212 along the Z direction has a chamfer 2121. The distance between the chamfer 2121 and the solder mark 4 along the Z direction is H3, where the value of H3 is in the range of 0.2 mm ≤ H3 ≤ 10 mm. It should be noted that the chamfer 2121 is set around the lower edge of the boss 212. H3 refers to the distance between the upper end of the chamfer 2121 and the lower end of the solder mark 4 along the Z direction. The upper end refers to the upper end along the Z direction, and the lower end refers to the lower end along the Z direction. That is, the upper end of the chamfer 2121 is the end of the chamfer 2121 closer to the plate 211 along the Z direction, and the lower end of the solder mark 4 is the end of the solder mark 4 away from the plate 211 along the Z direction. The lower end of the boss 212 is the end of the boss 212 away from the plate 211 along the Z direction. If H3 is less than 0.2 mm, the solder mark 4 is too close to the chamfer 2121, which is prone to breakage during welding, resulting in poor welding. If H3 is greater than 10 mm, the solder mark 4 is too far from the chamfer 2121, and the size of the boss 212 protruding downward along the Z direction from the connecting piece 3 is too large, which wastes materials and occupies too much space inside the cell, compressing the space for setting the electrode group, which is not conducive to improving the energy density of the cell.

[0044] Therefore, by setting the lower edge of the boss 212 as a chamfer 2121, the chamfer 2121 provides a guide for the assembly of the boss 212 into the positioning hole 31, which facilitates the smooth assembly of the two and helps to improve the assembly yield. At the same time, by limiting the distance between the chamfer 2121 and the solder mark 4 in the Z direction to a value between 0.2 mm and 10 mm, welding explosions can be avoided, welding quality can be guaranteed, material waste can be avoided, and the boss 212 can be prevented from occupying too much space inside the cell, which helps to improve the energy density of the cell.

[0045] Optionally, the value of H3 is any one of 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 5 mm, 7 mm, 9 mm, 10 mm, or a value between any two of these values.

[0046] In one embodiment, the distance along the Z-direction between the lower surface of the boss 212 and the lower surface of the connecting piece 3 is H4, where the value of H4 is in the range of 2 mm ≤ H4 ≤ 10 mm. The lower surface refers to the lower surface along the Z-direction. H4 is the dimension by which the boss 212 protrudes from the lower surface of the connecting piece 3 along the Z-direction. If H4 is less than 2 mm, the protrusion dimension of the boss 212 is insufficient, resulting in insufficient space for side welding, which is detrimental to smooth welding and makes it difficult to guarantee welding quality. If H4 is greater than 10 mm, the protrusion dimension of the boss 212 is too large, wasting material and space. Therefore, by limiting H4 to a value within the range of 2 mm to 10 mm, the boss 212 protrudes downwards relative to the connecting piece 3 by a reasonable dimension. This provides sufficient space for side welding, ensuring smooth welding, improving welding efficiency and quality, while avoiding waste of material and space, thus saving costs and increasing the energy density of the battery cell.

[0047] Optionally, the value of H4 is any one of 2 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, or a value between any two of these values.

[0048] In one embodiment, further combination Figure 3 As shown, the thickness of the connecting piece 3 along the Z direction is T, where the value of T ranges from 0.5 mm to 3 mm. If T is less than 0.5 mm, the thickness of the connecting piece 3 is too small, resulting in insufficient structural strength and insufficient space for welding. If T is greater than 3 mm, the connecting piece 3 is too thick, wasting material and space. Therefore, by limiting T to a range of 0.5 mm to 3 mm, it is possible to ensure that the connecting piece 3 has sufficient structural strength, improves reliability, and provides sufficient space for welding, thereby ensuring welding quality, while also avoiding waste of material and space, thus saving costs.

[0049] Optionally, the value of T is any one of 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, or a value between any two of these values.

[0050] In one embodiment, the connecting piece 3 includes a pole post connecting area 301 and a tab connecting area 302 connected along the X direction. The pole post connecting area 301 is correspondingly disposed with the base plate 21, and a positioning hole 31 is provided on the pole post connecting area 301. The upper surface of the pole post connecting area 301 is attached to the lower surface of the plate 211. The pole post connecting area 301 is electrically connected to the pole post 2 by welding to the boss 212. The tab connecting area 302 is used for welding to the tabs on the pole assembly. The thickness of both the pole post connecting area 301 and the tab connecting area 302 along the Z direction is T. Here, the upper surface refers to the upper surface along the Z direction, and the lower surface refers to the lower surface along the Z direction; the X direction refers to... Figures 1 to 6The direction indicated by the middle arrow "X" is specifically the length direction of the cover plate assembly.

[0051] In one embodiment, the connecting piece 3 is stepped, and the pole connecting area 301 is bent upward in the Z direction relative to the tab connecting area 302 so that there is a certain gap between the tab connecting area 302 and the second plastic part 8, providing a space for welding the tab on the tab connecting area 302. Then, the upper surface of the tab connecting area 302 is lower than the upper surface of the pole connecting area 301, and the upper surface of the tab connecting area 302 is not in contact with the lower surface of the plate 211.

[0052] In one embodiment, further combination Figure 4 As shown, the distance along the X direction between the tab connection area 302 and the solder mark 4 is W3, where the value of W3 ranges from 0.5 mm to 30 mm. It should be noted that W3 refers to the distance along the X direction between the tab connection area 302 and the solder mark 4 within the XZ plane passing through the center line of the positioning hole 31. If W3 is less than 0.5 mm, the tab connection area 302 is too close to the solder mark 4, resulting in insufficient space around the solder mark on the connecting piece 3, making it prone to soldering defects. If W3 is greater than 30 mm, the space around the solder mark on the connecting piece 3 is too large, wasting space and materials. Therefore, by limiting W3 to a value between 0.5 mm and 30 mm, soldering defects can be avoided, ensuring welding quality, while also preventing wasted space and materials, thus saving production costs.

[0053] Optionally, the value of W3 is any one of 0.5 mm, 1 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, or a value between any two of these values.

[0054] In one embodiment, the distance between the wall of the positioning hole 31 and the outer peripheral surface of the boss 212 in the XY plane is g1, where the value of g1 ranges from 0 mm to 1 mm. It should be noted that the boss 212 passes through the positioning hole 31. When g1 equals 0 mm, the outer peripheral wall of the boss 212 fits snugly against the wall of the positioning hole 31. g1 cannot be less than 0 mm; otherwise, interference will occur between the boss 212 and the wall of the positioning hole 31, and the boss 212 cannot be installed into the positioning hole 31. When g1 is greater than 0 mm, the boss 212 and the positioning hole 31 have a clearance fit, and a portion of the solder mark 4 is located within this clearance. If g1 is greater than 1 mm, the clearance between the wall of the positioning hole 31 and the outer peripheral surface of the boss 212 is too large, which will lead to poor solder joints during welding. Therefore, by limiting g1 to a value within the range of 0 mm to 0.8 mm, it is possible to ensure the smooth assembly of the boss 212 of the pole post 2 and the positioning hole 31 of the connecting piece 3, and to avoid welding defects such as blasting during the welding process, thereby ensuring the welding quality.

[0055] Optionally, the value of g1 is any one of 0 mm, 0.1 mm, 0.2 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, 1 mm, or a value between any two of these values.

[0056] In one embodiment, the cover plate assembly further includes a sealing ring 5, which is located on the upper side of the plate 211 along the Z direction and is fitted onto the column 22. The distance between the solder mark 4 and the sealing ring 5 along the Z direction is g2, wherein the value of g2 is in the range of 1.2 mm ≤ g2 ≤ 5 mm. The upper side of plate 211 along the Z direction refers to the side of plate 211 facing the cover plate body 1 along the Z direction; the lower surface of sealing ring 5 is in contact with the upper surface of plate 211, sealing ring 5 is sleeved on post 22 and at least part of sealing ring 5 is pressed between cover plate body 1 and plate 211 to ensure the sealing between pole post 2 and cover plate body 1; if g2 is less than 1.2 mm, the distance between solder mark 4 and sealing ring 5 is too small, and the high temperature generated during welding will pass through connecting piece 3 and plate 211 and burn sealing ring 5, resulting in sealing failure; if g2 is greater than 5 mm, the distance between solder mark 4 and sealing ring 5 is large, and correspondingly, the thickness of plate 211 along the Z direction needs to be increased, resulting in plate 211 being too thick, wasting material, and increasing the weight of pole post 2, which is not conducive to improving the energy density of the cell.

[0057] Therefore, by limiting g2 to a value within the range of 1.2 mm to 5 mm, it is possible to avoid excessive heat transfer during welding to the sealing ring 5, which could burn the sealing ring 5 and thus prevent sealing failure, ensuring the sealing reliability between the pole post 2 and the cover plate body 1 and improving safety. It is also possible to avoid the plate body 211 being too thick, thus avoiding material waste and excessive weight of the pole post 2, thereby saving costs and improving the energy density of the battery cell.

[0058] Optionally, the value of g2 is any one of 1.2 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, or a value between any two of these values.

[0059] In one embodiment, the orthographic projection of the boss 212 along the Z direction in the XY plane is circular (e.g., ...). Figure 5 (as shown), elliptical or polygonal (such as) Figure 6(As shown). The shape of the boss 212 can be selected according to the actual needs of the product. Circular and elliptical structures are simple and easy to process and form. Polygons themselves have positioning and anti-rotation functions, which can further improve the assembly yield of the connecting piece 3 and the boss 212. It should be noted that the shape of the orthographic projection of the boss 212 along the Z direction in the XY plane is the shape of the outer periphery of the boss 212. The opening shape of the positioning hole 31 is the same as the shape of the outer periphery of the boss 212, ensuring stable assembly of the connecting piece 3 and the boss 212. Among them, the polygon can be a triangle, quadrilateral, etc.

[0060] In one embodiment, the number of bosses 212 is one or more, and the number of positioning holes 31 is equal to and corresponds one-to-one with the number of bosses 212. "Multiple" refers to two or more. The number of positioning holes 31 on the connecting piece 3 is equal to the number of bosses 212, and the number of bosses 212 is equal to the number of mating positioning holes 31 and bosses 212. The number of bosses 212 can be flexibly selected. When there is only one boss 212, the structure is simple and easy to process. When there are two or more bosses 212, the positioning accuracy during the assembly process of the connecting piece 3 and the pole post 2 can be further improved, the assembly quality can be improved, and the welding quality between the connecting piece 3 and the pole post 2 can be further guaranteed.

[0061] In one embodiment, the cover plate assembly further includes a riveting block 6, which is disposed on the side of the cover plate body 1 facing away from the bottom plate 21 along the Z direction. The post 22 of the pole post 2 extends out of the upper surface of the cover plate body 1 along the Z direction, and the riveting block 6 is riveted to the post 22 of the pole post 2.

[0062] In one embodiment, the cover plate assembly further includes a first plastic part 7 and a second plastic part 8. The first plastic part 7 is disposed between the riveting block 6 and the cover plate body 1 to ensure insulation between the riveting block 6 and the cover plate body 1. The second plastic part 8 is disposed on the side of the cover plate body 1 away from the riveting block 6 along the Z direction to ensure insulation between the cover plate body 1 and the electrode assembly. Specifically, the first plastic part 7 is an upper plastic and the second plastic part 8 is a lower plastic.

[0063] In this embodiment, the cover plate assembly has a boss 212 on the base plate 21 of the pole post 2. The connecting piece 3 is fitted onto the boss 212 through the positioning hole 31. Along the Z direction, the boss 212 protrudes downward from the lower surface of the connecting piece 3. The connecting piece 3 and the boss 212 are welded together by side welding, which increases the sliding height stroke of the connecting piece 3 into the boss 212. When the positioning and installation of the automatic line equipment is incorrect, it provides sufficient stroke and time for the connecting piece 3 to automatically correct and align during the sliding process, thereby realizing automatic correction and alignment, avoiding misalignment during pressing and causing the connecting piece 3 to be damaged by the boss 212, thereby improving the assembly yield and welding yield between the connecting piece 3 and the pole post 2.

[0064] According to an embodiment of the present invention, another aspect provides a battery cell, comprising: a housing, an electrode assembly, and the aforementioned cover plate assembly. The housing has an open end; the electrode assembly is disposed in the inner cavity of the housing; and the cover plate assembly covers the open end of the housing. The electrode assembly has tabs extending from the side facing the cover plate assembly, and the tabs are electrically connected to a connecting piece 3 in the cover plate assembly, thereby achieving electrical connection between the terminal post 2 and the electrode assembly through the connecting piece 3.

[0065] Optionally, the battery cell is a lithium-ion battery cell.

[0066] The following examples and comparative examples verify the impact of different parameter values ​​on the battery cell. The parameter settings and verification results for the examples and comparative examples are shown in Table 1. Specifically, during the battery cell manufacturing process, it is observed whether there are any welding defects between the connecting piece and the terminal; after the battery cell is assembled, a vibration test is performed on the battery cell to test whether the battery cell has an open circuit.

[0067] Table 1

[0068] As can be seen from Table 1, for the cells of Examples 1 to 5, all parameters are within the range defined in this application, the battery did not fail, and the cell performance is good.

[0069] For the battery cell in Comparative Example 1, the distance H3 along the Z direction between the chamfer 2121 and the solder mark 4 is 0.18 mm, which is less than the lower limit of H3 (0.2 mm) defined in this application and is outside the range defined in this application. During the manufacturing process, the solder joint between the connecting piece and the base plate explodes. It can be seen that when H3 exceeds the range defined in this application, it will cause poor soldering.

[0070] For the cell of Comparative Example 2, the weld width W2 of the portion of solder 4 located on the boss 212 in the XY plane is 0.28 mm, which is less than the lower limit of W2 (0.3 mm) defined in this application and is not within the range defined in this application. For the cell of Comparative Example 3, the weld depth H2 of the portion of solder 4 located on the boss 212 along the Z direction is 0.48 mm, which is less than the lower limit of H2 (0.5 mm) defined in this application and is not within the range defined in this application. The cells of Comparative Examples 2 and 3 experienced open circuits and detachment of the connecting piece after the cell vibration test. It is evident that when W2 or H2 exceeds the range defined in this application, it is difficult to guarantee the welding strength between the connecting piece and the electrode, and welding failure and detachment of the connecting piece are likely to occur during cell use.

[0071] For the battery cell of Comparative Example 4, the weld width W1 of the portion of solder 4 located on the connecting piece 3 in the XY plane is 0.79 mm, which is less than the lower limit of W1 (0.8 mm) defined in this application and is not within the range defined in this application. For the battery cell of Comparative Example 5, the weld depth H1 of the portion of solder 4 located on the connecting piece 3 along the Z direction is 0.28 mm, which is less than the lower limit of H1 (0.3 mm) defined in this application and is not within the range defined in this application. In both Comparative Example 4 and Comparative Example 5, the battery cells experienced a circuit break and the connecting piece detached after the cell vibration test. It is evident that when W1 or H1 exceeds the range defined in this application, it is difficult to guarantee the welding strength between the connecting piece and the electrode post, and welding failure and connecting piece detachment are likely to occur during battery cell use.

[0072] Unless otherwise stated, the values ​​of all parameters mentioned in this application can be determined using testing methods commonly used in the art. Unless otherwise stated, the test temperature for all parameters is 25°C.

[0073] Although embodiments of the 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 invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A cover plate assembly, characterized in that, include: The cover plate body has pole hole; An electrode post includes a base plate and a post body. The post body is inserted into the electrode post hole. The base plate includes a plate body and a boss. The plate body is connected to the post body, and the plate body is located on the lower side of the cover plate body along the Z direction. The boss is connected to the lower surface of the plate body along the Z direction. A connecting piece is disposed on the lower side of the plate along the Z direction. A positioning hole is provided on the connecting piece. The connecting piece is sleeved on the boss through the positioning hole. The boss protrudes from the lower surface of the connecting piece along the Z direction. The boss is welded to the connecting piece to form a weld mark. The weld mark is arranged circumferentially around the positioning hole.

2. The cover plate assembly according to claim 1, characterized in that, The weld width of the portion of the solder mark located on the connecting piece in the XY plane is W1, wherein the value of W1 is in the range of 0.8 mm ≤ W1 ≤ 3 mm; And / or, the portion of the solder mark located on the connecting piece has a penetration depth of H1 along the Z direction, wherein the value of H1 is in the range of 0.3 mm ≤ H1 ≤ 1.5 mm.

3. The cover plate assembly according to claim 1, characterized in that, The weld width of the portion of the solder mark located on the boss in the XY plane is W2, where the value of W2 ranges from 0.3 mm to 1.5 mm. And / or, the portion of the solder mark located on the boss has a penetration depth of H2 along the Z direction, wherein the value of H2 is in the range of 0.5 mm ≤ H2 ≤ 3 mm.

4. The cover plate assembly according to claim 1, characterized in that, The lower edge of the boss along the Z direction is chamfered, and the distance between the chamfer and the solder mark along the Z direction is H3, wherein the value of H3 is in the range of 0.2 mm ≤ H3 ≤ 10 mm.

5. The cover plate assembly according to claim 1, characterized in that, The distance along the Z direction between the lower surface of the boss and the lower surface of the connecting piece is H4, wherein the value of H4 is in the range of 2 mm ≤ H4 ≤ 10 mm. And / or, the thickness of the connecting piece along the Z direction is T, wherein the value of T ranges from 0.5 mm to 3 mm.

6. The cover plate assembly according to claim 1, characterized in that, The connecting piece includes a pole post connecting area and a tab connecting area connected along the X direction. The pole post connecting area is correspondingly provided with the base plate, and the positioning hole is provided on the pole post connecting area. The upper surface of the pole post connecting area is attached to the lower surface of the plate body. The distance between the tab connecting area and the solder mark along the X direction is W3, wherein the value of W3 is in the range of 0.5 mm ≤ W3 ≤ 30 mm.

7. The cover plate assembly according to claim 1, characterized in that, The distance between the positioning hole wall and the boss in the XY plane is g1, where the value of g1 is in the range of 0 mm ≤ g1 ≤ 1 mm.

8. The cover plate assembly according to claim 1, characterized in that, The cover plate assembly further includes a sealing ring, which is located on the upper side of the plate along the Z direction and is fitted onto the column. The distance between the weld and the sealing ring along the Z direction is g2, wherein the value of g2 is in the range of 1.2 mm ≤ g2 ≤ 5 mm.

9. The cover plate assembly according to any one of claims 1 to 8, characterized in that, The orthographic projection of the boss along the Z direction in the XY plane is circular, elliptical, or polygonal. And / or, the number of the bosses is one or more, and the number of the positioning holes is equal to the number of the bosses and corresponds one-to-one.

10. A battery cell, characterized in that, include: The shell has an open end; The electrode assembly is disposed within the inner cavity of the housing; The cover assembly according to any one of claims 1 to 9 is provided covering the opening end of the housing.

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