Battery top cover and square battery

Abstract

A battery top cover and a square battery. The battery top cover comprises a cover plate assembly (3) and a negative electrode terminal (2) provided on the cover plate assembly (3). The cover plate assembly (3) has an outer side surface (30) and an inner side surface opposite to each other. The negative electrode terminal (2) comprises a first terminal and a second terminal. The first terminal is arranged on the outer side surface (30). One end of the second terminal is connected to the first terminal, part of the second terminal abuts against the outer side surface (30), and the other end of the second terminal passes through the cover plate assembly (3) and extends to the side of the inner side surface.

Description

Battery top cover and square battery

[0001] The present application claims priority to the Chinese patent application No. 202421397966.9, filed on June 18, 2024, to the Chinese Patent Office, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of battery manufacturing, in particular to a battery top cover and a square battery. BACKGROUND

[0003] A square battery is a common lithium battery, which has a cuboid structure as a whole, and is therefore called a square battery. The related square battery mainly includes a shell, a core package and a top cover assembly. The core package is installed inside the shell and filled with electrolyte inside the shell. The top cover assembly is installed at the opening end of the shell so that the core package and the electrolyte are sealed between the shell and the top cover assembly. The top cover assembly is provided with a positive terminal and a negative terminal for connecting with an external circuit. In order to ensure the use performance of the positive and negative terminals, the positive terminal is usually made of aluminum material, and the negative terminal is usually made of copper-aluminum composite material. The negative terminal includes an aluminum part for connecting with the external circuit and a copper part for connecting with the core package, and the copper part and the aluminum part of the negative terminal are formed into one body by friction welding or cold heading process. SUMMARY

[0004] When the negative terminal is applied to a low-voltage battery or a blade battery with a relatively small thickness, the width size of the negative terminal is also small, which is limited by the processing range of the cold heading equipment, resulting in a large processing difficulty of the negative terminal, and the bonding strength of the bonding surface of the aluminum part and the copper part is weak, which affects the service life of the negative terminal. In addition, the bonding surface of the copper part and the aluminum part is weakened due to long-term immersion in electrolyte. At the same time, during the use of the square battery, the bonding surface is pulled in opposite directions due to the connection of the copper part and the aluminum part with the external circuit and the core package respectively, which further causes the negative terminal to be at risk of breaking.

[0005] The present application provides a battery top cover and a square battery, which has a simple processing process, a small processing range limitation, a high bonding strength of the copper terminal and the aluminum terminal, and a long service life.

[0006] The battery top cover provided by the present application includes a cover plate assembly and a negative terminal arranged on the cover plate assembly. The cover plate assembly has opposite outer and inner sides. The negative terminal includes a first terminal and a second terminal made of different materials. The first terminal is arranged on the outer side. One end of the second terminal is connected to the first terminal, and part of the second terminal abuts against the outer side. The other end of the second terminal penetrates through the cover plate assembly and extends to one side of the inner side.

[0007] Furthermore, the second terminal includes a mounting portion and a connecting portion disposed on the mounting portion, the connecting portion being located in the middle of the mounting portion, the periphery of the mounting portion abutting against the outer side surface, and the connecting portion passing through the cover plate assembly.

[0008] Furthermore, the width of the abutment surface between the mounting part and the cover plate assembly is greater than or equal to 2 mm.

[0009] Furthermore, the first terminal is provided with a mounting groove, the mounting part is inserted into the mounting groove, and the mounting part is flush with the opening of the mounting groove.

[0010] Furthermore, along the width direction of the mounting portion, the mounting groove extends through the first terminal.

[0011] Furthermore, the depth of the mounting groove is 0.5-1.5mm.

[0012] Furthermore, a mounting hole is provided through the first terminal, the mounting part is inserted into the mounting hole, and the two ends of the mounting part in the axial direction are respectively flush with the two ends of the first terminal.

[0013] Furthermore, the first terminal is an aluminum terminal, and the second terminal is a copper terminal.

[0014] Furthermore, the first terminal and the second terminal are welded together to form a solder mark, which is located on one side of the outer surface of the cover plate assembly.

[0015] Furthermore, the solder mark is recessed on one side of the first terminal facing the cover plate assembly; or,

[0016] The outer surface is recessed with a relief groove to avoid the solder mark.

[0017] Furthermore, it also includes a positive current collector and a negative current collector disposed on one side of the inner side of the cover plate assembly, and a positive terminal disposed on the cover plate assembly. The positive current collector and the negative current collector are respectively used to connect to the positive and negative tabs of the core package. The positive terminal is connected to the positive current collector, and the end of the second terminal opposite to the first terminal is connected to the negative current collector.

[0018] Furthermore, the cover plate assembly includes a top cover plate, an upper plastic bracket, a lower plastic bracket, and a sealing ring. The upper plastic bracket and the lower plastic bracket are respectively disposed on opposite sides of the top cover plate. The upper plastic bracket is provided with a receiving groove, the first terminal is inserted into the receiving groove, and the sealing ring is sleeved around the periphery of the second terminal.

[0019] This application also provides a square battery, including a casing, a core pack, and a battery top cover. The casing is a hollow structure with one open end. The core pack is installed inside the casing. The battery top cover is installed on the casing and is used to seal the opening of the casing. The positive terminal of the battery top cover is electrically connected to the positive tab of the core pack, and the negative terminal of the battery top cover is electrically connected to the negative tab of the core pack. Beneficial effects

[0020] The battery top cover provided in this application connects to the first terminal via a second terminal, with the end of the second terminal near the first terminal resting against the outer surface of the cover assembly. During the use of the prismatic battery, the second terminal is subjected to a downward pulling force exerted by the core pack. Since part of the second terminal rests against the outer surface, the cover assembly can support the second terminal. The pulling force is transmitted directly from the second terminal to the cover assembly, rather than from the second terminal to the first terminal, thereby preventing the negative terminal from breaking under stress and improving the bonding strength between the first and second terminals.

[0021] The square battery provided in this application has the same technical effect as the battery top cover provided in this application. Attached Figure Description

[0022] Figure 1 is a schematic diagram of the battery top cover according to an embodiment of this application;

[0023] Figure 2 is an exploded view of the battery top cover according to an embodiment of this application;

[0024] Figure 3 is a partial cross-sectional view of the battery top cover according to an embodiment of this application;

[0025] Figure 4 is a schematic diagram of the installation of the negative terminal and the upper plastic bracket according to an embodiment of this application;

[0026] Figure 5 is a schematic diagram of the installation of the negative terminal and the upper plastic bracket according to another embodiment of this application;

[0027] Figure 6 is an exploded view of the negative end of an embodiment of this application;

[0028] Figure 7 is a schematic diagram of the negative terminal of another embodiment of this application;

[0029] Figure 8 is an exploded view of the negative end of another embodiment of this application;

[0030] Figure 9 is a schematic diagram of a square battery according to an embodiment of this application.

[0031] In the picture:

[0032] 1. Positive terminal; 2. Negative terminal; 20. Solder mark; 21. Aluminum terminal; 211. Mounting groove; 212. Mounting hole; 213. First side; 214. Bevel; 22. Copper terminal; 221. Mounting part; 222. Connecting part; 3. Cover plate assembly; 30. Outer side; 31. Top cover plate; 32. Upper plastic bracket; 321. Receiving groove; 322. Clearance groove; 33. Lower plastic bracket; 34. Sealing ring; 35. Injection hole; 36. Explosion-proof valve; 4. Positive current collector; 5. Negative current collector; 51. First connecting plate; 52. Second connecting plate; 53. Connecting hole; 6. Housing. Embodiments of the present invention

[0033] In the description of this application, unless otherwise expressly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, where the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, where the first feature is at a lower horizontal level than the second feature.

[0035] In the description of this embodiment, the terms "upper," "lower," "left," "right," "front," and "rear," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. In addition, the terms "first" and "second" are used for distinction in description and have no special meaning.

[0036] As shown in Figure 1, this application provides a battery top cover for use in a prismatic battery. The overall shape of the battery top cover is similar to a cuboid, with its length direction as shown in the X direction, its width direction as shown in the Y direction, and its thickness direction as shown in the Z direction. The battery top cover includes a positive terminal 1, a negative terminal 2, a cover plate assembly 3, a positive current collector 4, and a negative current collector 5. Both the positive terminal 1 and the negative terminal 2 are used to connect to an external circuit to realize the current input or output of the prismatic battery. Along the length direction of the battery top cover, the positive terminal 1 and the negative terminal 2 are spaced apart on the cover plate assembly 3. Along the thickness direction of the battery top cover, two opposite sides of the cover plate assembly 3 are an outer side 30 and an inner side, respectively. The outer side 30 faces the outside of the prismatic battery, and the inner side faces the inside of the prismatic battery. The positive terminal 1 is mounted on the cover plate assembly 3, and the positive current collector 4 is located on the inner side of the cover plate assembly 3, that is, the positive current collector 4 is located inside the prismatic battery. The positive terminal 1 is connected to the positive current collector 4, and the positive tab on the core pack is welded and fixed to the positive current collector 4 to achieve a circuit connection between the positive terminal 1 and the positive terminal of the core pack. The negative terminal 2 is mounted on the cover plate assembly 3, and the negative current collector 5 is located on one side of the inner side of the cover plate assembly 3, that is, the negative current collector 5 is located inside the square battery. The negative terminal 2 is connected to the negative current collector 5, and the negative tab on the core pack is welded and fixed to the negative current collector 5 to achieve a circuit connection between the negative terminal 2 and the negative terminal of the core pack.

[0037] Referring to Figures 2 and 3, the cover assembly 3 includes a top cover plate 31, an upper plastic bracket 32, a lower plastic bracket 33, and a sealing ring 34. The upper plastic bracket 32 ​​is used to mount the positive terminal 1 and the negative terminal 2 for insulation protection. There are two upper plastic brackets 32, spaced apart along the length of the cover assembly 3 (X direction in the figure). The upper plastic brackets 32 are located on the side of the top cover plate 31 facing the outside of the square battery, and the positive terminal 1 and the negative terminal 2 are respectively mounted on the two upper plastic brackets 32. The lower plastic bracket 33 is located on the side of the top cover plate 31 facing the inside of the square battery, and it provides insulation protection for the positive and negative terminals and conductive components such as the positive and negative current collectors. Both the positive terminal 1 and the negative terminal 2 must pass through the top cover plate 31, and each of the positive terminal 1 and the negative terminal 2 is fitted with a sealing ring 34, which provides insulation and sealing between the positive and negative terminals and the top cover plate 31.

[0038] It should be noted that the upper plastic bracket 32 ​​cannot cover the entire side of the top cover 31 facing the outside of the square battery. Therefore, the side of the upper plastic bracket 32 ​​facing the outside of the square battery and the side of the top cover 31 facing the outside of the square battery but not covered by the upper plastic bracket 32 ​​together form the outer side 30 of the cover assembly 3. The lower plastic bracket 33 can cover the entire top cover 31, and the side of the lower plastic bracket 33 facing away from the top cover 31 forms the inner side of the cover assembly 3.

[0039] Specifically, the upper plastic bracket 32 ​​is provided with a receiving groove 321, the shape and size of which are configured to match the positive terminal 1 or the negative terminal 2. One end of the positive terminal 1 is inserted into the corresponding receiving groove 321 of the upper plastic bracket 32, and the other end passes through the cover plate assembly 3 and is connected to the positive current collector 4. One end of the negative terminal 2 is inserted into the corresponding receiving groove 321 of the upper plastic bracket 32, and the other end passes through the cover plate assembly 3 and is connected to the negative current collector 5.

[0040] Specifically, the negative terminal 2 includes a first terminal and a second terminal made of different materials. The first terminal is an aluminum terminal 21, and the second terminal is a copper terminal 22. The aluminum terminal 21 is disposed in the receiving groove 321 of the upper plastic bracket 32.

[0041] Alternatively, the groove 321 of the upper plastic bracket 32 ​​faces the outside of the square battery, and the aluminum terminal 21 is installed inside the groove 321, meaning the aluminum terminal 21 is located on the outer side 30 of the cover assembly 3. One end of the copper terminal 22 is inserted into the aluminum terminal 21 and welded to it using laser welding. The end of the copper terminal 22 facing away from the aluminum terminal 21 passes through the cover assembly 3 and extends to one side of the inner side of the cover assembly 3. That is, one end of the copper terminal 22 extends into the interior of the square battery to connect with the negative current collector 5.

[0042] Since the copper terminal 22 needs to pass through the cover plate assembly 3, through holes are provided on the upper plastic bracket 32, lower plastic bracket 33, and top cover plate 31 for the copper terminal 22 to pass through. The through hole on the upper plastic bracket 32 ​​is located at the bottom of the receiving groove 321. The cross-section of the end of the copper terminal 22 that is inserted into the aluminum terminal 21 is larger than the size of the through hole on the upper plastic bracket 32, so that the end of the copper terminal 22 that is inserted into the aluminum terminal 21 can abut against the bottom of the receiving groove 321, that is, part of the copper terminal 22 abuts against the outer side 30 of the cover plate assembly 3.

[0043] Understandably, the aluminum terminal 21 and the copper terminal 22 are fixed by laser welding. Compared with cold forging, this process is simpler and not limited by processing dimensions, while also resulting in a higher bonding strength between the aluminum terminal 21 and the copper terminal 22. Since the end of the copper terminal 22 closest to the outside of the square battery abuts against the outer side 30 of the cover assembly 3, part of the tensile force exerted by the core pack on the copper terminal 22 is distributed to the cover assembly 3, thereby reducing the tensile force on the bonding surface between the aluminum terminal 21 and the copper terminal 22. This prevents the negative terminal 2 from breaking at the bonding surface and improves the service life of the negative terminal 2.

[0044] Referring to Figures 3 and 6, the aluminum terminal 21 has a cuboid structure. Along the thickness direction (Z direction in the figures), the two opposite sides of the aluminum terminal 21 are the first side 213 and the second side. The first side 213 of the aluminum terminal 21 abuts against the bottom of the receiving groove 321, and the second side of the aluminum terminal 21 is used for connection with an external circuit. A mounting groove 211 is provided on the first side 213 of the aluminum terminal 21. The cross-section of the mounting groove 211 is rectangular, that is, the bottom of the mounting groove 211 is rectangular. Along the width direction (Y direction in the figures), the mounting groove 211 penetrates the aluminum terminal 21, that is, the width of the mounting groove 211 is equal to the width of the aluminum terminal 21.

[0045] Correspondingly, the copper terminal 22 includes a mounting portion 221 and a connecting portion 222 disposed on the mounting portion 221. The shape and size of the mounting portion 221 are configured to fit the mounting groove 211, that is, the mounting portion 221 has a cuboid structure. The mounting portion 221 is inserted into the mounting groove 211, and the mounting portion 221 is flush with the groove opening of the mounting groove 211. When the negative terminal 2 is installed on the upper plastic bracket 32, the first side 213 of the aluminum terminal 21 abuts against the bottom of the receiving groove 321, and the peripheral area of ​​the side of the mounting portion 221 facing the connecting portion 222 also abuts against the bottom of the receiving groove 321.

[0046] This can also be understood as the peripheries of both the aluminum terminal 21 and the mounting portion 221 abutting against the outer surface 30 of the cover assembly 3. It can be understood that by aligning the mounting portion 221 with the opening of the mounting groove 211, the mounting portion 221 is aligned with the first side surface 213 of the aluminum terminal 21, ensuring that both the aluminum terminal 21 and the mounting portion 221 abut against the bottom of the mounting groove 211. Furthermore, because the overall width of the battery top cover is relatively small, the width of the negative terminal 2 is also correspondingly smaller.

[0047] Therefore, when welding the copper terminal 22 and the aluminum terminal 21, welding only needs to be performed at both ends of the mounting portion 221 of the copper terminal 22 along its length (X direction in the figure), without welding the two ends of the mounting portion 221 along its width to the aluminum terminal 21. By connecting the mounting groove 211 of the aluminum terminal 21 to the outer wall of the aluminum terminal 21, the processing difficulty of the mounting groove 211 can be reduced while meeting the welding process requirements. Of course, in other embodiments, the cross-sectional shape of the mounting groove 211 can also be circular, square, triangular, elliptical, prismatic, polygonal (such as hexagonal), etc.

[0048] Specifically, the width of the abutment surface between the mounting part 221 and the cover plate assembly 3 is B, where B ≥ 2mm. Since the periphery of the mounting part 221 abuts against the upper plastic bracket 32, the abutment surface between the mounting part 221 and the cover plate assembly 3 is the same as the abutment surface between the mounting part 221 and the upper plastic bracket 32. In this embodiment, the upper plastic bracket 32 ​​has a through hole for the connecting part 222 to pass through. The width of the abutment surface refers to the distance from the edge of the mounting part 221 to the edge of the through hole along the radial direction of the through hole in the upper plastic bracket 32. In specific implementations, the width B of the abutment surface can be selected as 2mm, 2.5mm, 3mm, 3.5mm, 4mm, etc.

[0049] It should be noted that the specific selection of the width dimension B of the abutment surface can be comprehensively considered based on factors such as the material strength of the mounting part 221 and the thickness of the mounting part 221, so as to ensure that the mounting part 221 can be stably supported on the cover plate assembly 3.

[0050] Specifically, the connecting part 222 has a cylindrical structure and is located in the middle of the mounting part 221. One end of the connecting part 222 is connected to the mounting part 221, and the other end passes through the cover plate assembly 3 and is connected to the negative current collector 5. That is, the end of the connecting part 222 away from the mounting part 221 extends to one side of the inner surface of the cover plate assembly 3. Since the connecting part 222 is set as a cylindrical structure, the through hole opened on the cover plate assembly 3 is also a circular hole to facilitate processing. Of course, in other embodiments, the connecting part 222 can also be set as other shapes. For example, the cross-section of the connecting part 222 can also be triangular, square, rectangular, hexagonal, etc. Since the connecting part 222 passes through the cover plate assembly 3, the sealing ring 34 is correspondingly fitted around the periphery of the connecting part 222 of the copper terminal 22.

[0051] Specifically, the depth of the mounting groove 211 of the aluminum terminal 21 is equal to the thickness of the mounting portion 221 of the copper terminal 22. The depth of the mounting groove 211 is 0.5-1.5 mm, and correspondingly, the thickness of the mounting portion 221 is also 0.5-1.5 mm. Since the mounting portion 221 abuts against the outer side 30 of the cover assembly 3, the core pack inside the square battery will exert a tensile force on the mounting portion 221 through the connecting portion 222. Therefore, the thickness of the mounting portion 221 affects its ability to withstand tensile force. In practical applications, the thickness of the mounting portion 221 can be reasonably selected according to the specific structure of the square battery and the stress condition of the negative terminal 2.

[0052] In this embodiment, the thickness of the mounting part 221 and the depth of the mounting groove 211 include, but are not limited to, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm and 1.5mm.

[0053] In another embodiment, referring to FIG7 (partial reference numerals are shown in conjunction with FIG6), an mounting groove 211 is provided on the aluminum terminal 21, and the groove wall of the mounting groove 211 is not in communication with the outer wall of the aluminum terminal 21. The mounting part 221 has a cuboid structure and is inserted into the mounting groove 211. This structure allows all four sides of the mounting part 221 to be welded and fixed to the aluminum terminal 21, which helps to increase the welding length and improve the bonding strength between the aluminum terminal 21 and the copper terminal 22.

[0054] In another embodiment, referring to FIG8, a mounting hole 212 is provided through the aluminum terminal 21. The mounting hole 212 is a circular hole to facilitate processing. The copper terminal 22 includes a mounting portion 221 and a connecting portion 222 disposed on the mounting portion 221. Both the mounting portion 221 and the connecting portion 222 are cylindrical structures, and the diameter of the mounting portion 221 is larger than the diameter of the connecting portion 222. The mounting portion 221 is inserted into the mounting hole 212, and the two ends of the mounting portion 221 in the axial direction are respectively flush with the two end faces in the thickness direction of the aluminum terminal 21. This structure allows both opposite end faces of the aluminum terminal 21 to be welded to the mounting portion 221, thereby improving the bonding strength between the copper terminal 22 and the aluminum terminal 21.

[0055] Specifically, referring to Figures 3 and 4 (some reference numerals are shown in conjunction with Figure 6), the junction of the aluminum terminal 21 and the copper terminal 22 is welded to form a solder mark 20, which is located on one side of the outer surface 30 of the cover plate assembly 3. After the mounting portion 221 of the copper terminal 22 is inserted into the mounting groove 211 of the aluminum terminal 21, the side of the mounting portion 221 facing the connecting portion 222 is flush with the first side surface 213 of the aluminum terminal 21. Laser welding is performed on the junction of the side of the mounting portion 221 facing the connecting portion 222 and the first side surface 213 to form the solder mark 20. Since the periphery of the mounting portion 221 abuts against the outer surface 30 of the cover plate assembly 3, the solder mark 20 is also located on one side of the outer surface 30 of the cover plate assembly 3. This structure allows the solder mark 20 to be kept away from the interior of the square battery. Under the isolation effect of the cover plate assembly 3, the solder mark 20 can be prevented from being immersed in the electrolyte, thereby preventing the weakening of the bonding strength between the aluminum terminal 21 and the copper terminal 22 due to the long-term immersion of the solder mark 20 in the electrolyte.

[0056] To ensure that the first side 213 of the aluminum terminal 21 and the mounting portion 221 can smoothly abut against the bottom of the receiving groove 321, the solder mark 20 is recessed on the side of the aluminum terminal 21 facing the cover plate assembly 3, that is, the solder mark 20 is recessed in the first side 213 of the aluminum terminal 21. In practical applications, a bevel 214 can be machined at the groove opening of the mounting groove 211 of the aluminum terminal 21, and a bevel 214 can be machined around the periphery of the mounting portion 221, so that the solder mark 20 formed after welding can be recessed in the first side 213 of the aluminum terminal 21, avoiding direct contact between the solder mark 20 and the bottom of the receiving groove 321.

[0057] In another embodiment, referring to FIG5, the aluminum terminal 21 and the copper terminal 22 are welded together to form a solder mark 20, which is located on one side of the outer surface 30 of the cover plate assembly 3. The bottom of the receiving groove 321 is provided with a relief groove 322 (i.e., the relief groove 322 is provided on the outer surface 30), and the relief groove 322 is directly opposite to the solder mark 20. By providing the relief groove 322 to avoid the portion of the solder mark 20 protruding from the first side surface 213 of the aluminum terminal 21, it is ensured that the first side surface 213 of the aluminum terminal 21 and the mounting portion 221 can be flatly abutted against the bottom of the receiving groove 321 (outer surface 30).

[0058] Specifically, referring to Figures 2 and 3 (some reference numerals are shown in conjunction with Figure 6), the negative current collector 5 includes a first connecting plate 51 and a second connecting plate 52. The first connecting plate 51 is parallel to the cover plate assembly 3. One end of the second connecting plate 52 is connected to the first connecting plate 51, and the other end extends in a direction away from the cover plate assembly 3. The length of the second connecting plate 52 extends along the thickness direction of the battery top cover, and the negative electrode tab on the core pack is welded to the second connecting plate 52. The first connecting plate 51 is installed on the inner side of the cover plate assembly 3, and a connecting hole 53 is provided through the first connecting plate 51. The end of the connecting part 222 away from the mounting part 221 is inserted into the connecting hole 53, and the mounting part 221 is welded and fixed to the first connecting plate 51 of the negative current collector 5 by laser welding. The connecting hole 53 is a countersunk hole, with one end of the larger hole of the connecting hole 53 facing the inside of the square battery and one end of the smaller hole of the connecting hole 53 facing the outside of the square battery. The connecting part 222 passes through the small hole of the connecting hole 53 so that the large hole of the connecting hole 53 can be used to accommodate the weld mark 20 formed between the negative current collector 5 and the connecting part 222, so as to ensure the surface flatness of the first connecting plate 51.

[0059] Specifically, the cover assembly 3 is also provided with an injection hole 35 and an explosion-proof valve 36. The injection hole 35 is used to inject electrolyte into the interior of the square battery. The explosion-proof valve 36 is used to provide pressure relief protection in the event of thermal runaway of the square battery.

[0060] Specifically, the positive terminal 1 and the negative terminal 2 have the same structure, and the structure of the positive terminal 1 will not be described in detail here. The positive terminal 1 is made of aluminum and can be integrally formed by stamping, casting, or other methods.

[0061] As shown in Figure 9, a square battery is also provided, including a casing 6, a core pack, and a battery top cover. The overall shape of the square battery is cuboid, with its length direction as shown in the X direction, its width direction as shown in the Y direction, and its height direction as shown in the Z direction. The casing 6 is a hollow structure with one open end, and the core pack is installed inside the casing 6. The core pack is formed by stacking or winding positive electrode plates, negative electrode plates, and a separator in a certain order. The battery top cover is installed at the open end of the casing 6 and is used to seal the opening of the casing 6. The interior of the casing 6 is also filled with electrolyte. The outer side 30 of the cover assembly 3 faces away from the casing 6, and the inner side of the cover assembly 3 faces the casing 6. The positive current collector 4 and the negative current collector 5 are located inside the casing 6, and are located at opposite ends of the length direction of the square battery. The positive tab of the core pack is welded and fixed to the positive current collector 4, and the negative tab of the core pack is welded and fixed to the negative current collector 5, so as to realize the electrical connection between the positive terminal 1 on the battery top cover and the positive tab of the core pack, and the electrical connection between the negative terminal 2 on the battery top cover and the negative tab of the core pack.

[0062] The significant advantage of this embodiment is that by connecting the second terminal to the first terminal and having the end of the second terminal closer to the first terminal abut against the outer surface 30 of the cover assembly 3, the second terminal is subjected to a downward pulling force from the core pack during the use of the square battery. Since part of the second terminal abuts against the outer surface 30, the cover assembly 3 can support the second terminal. The pulling force is directly transmitted from the second terminal to the cover assembly 3, rather than from the second terminal to the first terminal, thus preventing the negative terminal 2 from breaking under stress and improving the bonding strength between the first and second terminals. After the second terminal and the first terminal are inserted, they are fixed by welding at their joint. Compared to the corresponding cold forging process, this method is simpler and not limited by processing dimensions. Simultaneously, since part of the second terminal abuts against the outer surface 30, the welding position between the second terminal and the first terminal is located on one side of the outer surface 30 of the cover assembly 3, keeping the weld seam away from the interior of the square battery. This prevents the weld seam from being immersed in the electrolyte for a long time and thus avoids breakage, improving the service life of the negative terminal 2.

Claims

1. A battery top cover comprising a cover plate assembly and a negative terminal disposed on the cover plate assembly, the cover plate assembly having opposite outer and inner side surfaces, characterized in that, The negative terminal comprises a first terminal and a second terminal made of different materials, the first terminal is arranged on the outer side, one end of the second terminal is connected with the first terminal, and part of the second terminal abuts on the outer side, and the other end of the second terminal penetrates through the cover plate assembly and extends to one side of the inner side.

2. The battery header of claim 1, wherein, The second terminal comprises a mounting portion and a connecting portion arranged on the mounting portion, the connecting portion is located in the middle of the mounting portion, the peripheral portion of the mounting portion abuts on the outer side, and the connecting portion penetrates the cover plate assembly.

3. The battery header of claim 2, wherein, The width dimension of the abutting surface between the mounting portion and the cover plate assembly is greater than or equal to 2mm.

4. The battery header of claim 2, wherein, The first terminal is provided with a mounting groove, the mounting portion is inserted into the mounting groove, and the peripheral edge of the mounting portion is flush with the slot of the mounting groove.

5. The battery header of claim 4, wherein, The mounting groove penetrates the first terminal along the width direction of the mounting portion.

6. The battery header of claim 4, wherein, The depth dimension of the mounting groove is 0.5-1.5mm.

7. The battery cover of claim 2, wherein, The first terminal is provided with a mounting hole penetrating through, the mounting portion is inserted into the mounting hole, and the two ends of the mounting portion in the axial direction are flush with the two ends of the first terminal respectively.

8. The battery cover of any one of claims 1 to 7, wherein, The first terminal is an aluminum terminal, and the second terminal is a copper terminal.

9. The battery cover of any one of claims 1 to 7, wherein, The junction of the first terminal and the second terminal is welded to form a welding mark, and the welding mark is located on one side of the outer side of the cover plate assembly.

10. The battery header of claim 9, wherein, The welding mark is recessed on the side of the first terminal facing the cover plate assembly; or, the outer side is recessed with a avoiding groove for avoiding the welding mark.

11. The battery cover of any one of claims 1 to 7, wherein, Further comprising a positive current collector and a negative current collector arranged on one side of the inner side of the cover plate assembly, and a positive terminal arranged on the cover plate assembly, the positive current collector and the negative current collector are respectively used for connecting with the positive tab and the negative tab of the core package, the positive terminal is connected with the positive current collector, and one end of the second terminal away from the first terminal is connected with the negative current collector.

12. The battery cover of any one of claims 1 to 7, wherein, The cover plate assembly comprises a top cover sheet, an upper plastic support, a lower plastic support and a sealing ring, the upper plastic support and the lower plastic support are arranged on the opposite sides of the top cover sheet respectively, the upper plastic support is provided with a containing groove, the first terminal is inserted into the containing groove, and the sealing ring is sleeved on the peripheral portion of the second terminal.

13. A square battery, characterized by The battery top cover comprises a shell, a core package and a battery top cover according to any one of claims 1-12, the shell is a hollow structure with one end open, the core package is installed in the shell, the battery top cover is installed on the shell and used for sealing the opening of the shell, the positive terminal of the battery top cover is electrically connected with the positive tab of the core package, and the negative terminal of the battery top cover is electrically connected with the negative tab of the core package.

Images