Cover plate assembly and battery

Abstract

The utility model relates to battery technical field discloses the cover plate subassembly and battery, include: cover plate body has the first surface and the second surface who sets up oppositely along the thickness direction, the cover plate body is equipped with the pole hole who sets up along the thickness direction through, the pole body is worn in the pole hole, the pole body has the first end face that extends out the first surface, the pole body inside is equipped with the heat dissipation cavity, the heat dissipation cavity sets up through the first end face. The utility model discloses the heat dissipation cavity on the pole body is equipped with, can increase the contact area of pole body and outside environment, namely increase the heat dissipation area of pole body, improve the heat dissipation effect of pole body, avoid the heat of pole body backflow and cause the influence to the internal environment of battery, improve the safety performance of battery.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a cover plate assembly and a battery. Background Technology

[0002] Due to the inherent characteristics of lithium batteries, they generate significant heat during repeated use. If this accumulated heat cannot be effectively dissipated, it will affect the battery's stability, shorten its lifespan, and may even trigger safety risks such as thermal runaway. The terminals, serving as the battery's input and output ports, have high current density and generate substantial heat, making them prone to backflow and deteriorating the battery's internal environment. Utility Model Content

[0003] This invention provides a cover plate assembly and a battery to solve the problem in the prior art where the electrode posts generate a lot of heat, which can easily lead to heat backflow and deteriorate the internal environment of the battery.

[0004] In a first aspect, this utility model provides a cover plate assembly, comprising: The cover plate body has a first surface and a second surface that are arranged opposite to each other along the thickness direction, and the cover plate body has a pole hole that is arranged through the thickness direction. The electrode body is inserted through the electrode hole. The electrode body has a first end face extending out of the first surface. A heat dissipation cavity is formed inside the electrode body and the heat dissipation cavity is disposed through the first end face.

[0005] Beneficial effects: By opening a heat dissipation cavity on the electrode body, the contact area between the electrode body and the external environment can be increased, that is, the heat dissipation area of ​​the electrode body can be increased, the heat dissipation effect of the electrode body can be improved, the heat of the electrode body can be prevented from flowing back into the electrode body and affecting the internal environment of the battery, thus improving the safety performance of the battery.

[0006] In one optional embodiment, the heat dissipation cavity includes a first cavity segment and a second cavity segment that are connected along the thickness direction. The first cavity segment extends through the first end face, and the second cavity segment is located on the side of the first cavity segment away from the first end face. The diameter of the second cavity segment is larger than the diameter of the first cavity segment.

[0007] Beneficial effects: While ensuring the welding area of ​​the electrode body and the busbar, the opening range of the heat dissipation cavity is increased, thereby improving the heat dissipation effect of the electrode body.

[0008] In one alternative embodiment, a busbar welding position is formed on the portion of the first end face surrounding the first cavity segment, the diameter of the busbar welding position being K and the diameter of the first cavity segment being G, satisfying 0 < G ≤ K.

[0009] Beneficial effects: While avoiding the impact on the welding of the electrode body and busbar, it increases the opening range of the first cavity section and improves the heat dissipation effect of the electrode body.

[0010] In one optional embodiment, the pole body forms a cavity end wall around a portion of the first cavity segment, and forms a cavity side wall around a portion of the second cavity segment, wherein the thickness of the cavity side wall is not less than the thickness of the cavity end wall.

[0011] Beneficial effects: This configuration ensures the overall structural strength of the electrode body and guarantees its current carrying capacity.

[0012] In one optional embodiment, the cavity sidewall includes a first wall segment and a second wall segment, the first wall segment being connected to the cavity end wall, the second wall segment being connected to the end of the first wall segment away from the cavity end wall, the outer peripheral surface of the second wall segment extending radially beyond the outer peripheral surface of the first wall segment to form a stepped surface at the connection between the first wall segment and the second wall segment, and the cover plate assembly further includes a pressing structure, the pressing structure being disposed opposite to the first surface and pressing against the stepped surface.

[0013] In one optional embodiment, the thickness of the cavity end wall is A, the thickness of the first wall segment is C, and the thickness of the second wall segment is D, satisfying D > C ≥ A; and / or, The thickness of the cavity end wall is A, and the thickness of the pressing structure is B, satisfying B≥A; and / or, The thickness of the first wall segment is C, and the thickness of the second wall segment is D, satisfying 0.1mm ≤ DC ≤ 1mm; and / or, The thickness of the cavity end wall is A, satisfying A≥1mm; and / or, The thickness of the pressing structure is B, which satisfies 1mm≤B≤5mm.

[0014] Beneficial effects: It ensures that the thickness of the pressing structure is not less than the thickness of the cavity end wall, guarantees that the welding strength between the pressing structure and the electrode body meets the requirements, avoids the risk of welding failure during battery use, improves safety, and extends service life; By limiting the range of DC values, the welding effect of the pressing structure and the pole body is ensured, while the processing and forming of the pole body is facilitated, and the material utilization rate during the forming of the pole body is guaranteed. By limiting the range of the thickness A of the cavity end wall, the welding strength of the pole body and the busbar is guaranteed. By limiting the range of the thickness B of the pressing structure, the welding strength of the pressing structure and the electrode body is ensured while avoiding any impact on the volumetric energy density and gravimetric energy density of the battery.

[0015] In one optional embodiment, the cover plate assembly further includes a connecting piece, which is spaced apart from the second surface along the thickness direction. The connecting piece has a through mounting hole along the thickness direction. The outer peripheral surface of the pole body protrudes at one end away from the first end face to form a support foot. The support foot is inserted into the mounting hole. The outer peripheral surface of the support foot and the connecting piece are welded around the hole wall of the mounting hole by seam welding.

[0016] Beneficial effects: The support feet of the electrode body are inserted into the mounting holes, so that the electrode body and the connecting piece partially overlap in the thickness direction, reducing the distance between the connecting piece and the second surface, allowing the connecting piece to fully occupy the thickness space of the cover body, leaving more space for the battery cell, and improving the volumetric energy density of the battery.

[0017] In one optional embodiment, the thickness of the support leg is E, and the thickness of the cavity end wall is A, satisfying A≥E; and / or, The thickness of the support leg is E, and the thickness of the connecting piece is T, satisfying E≥T.

[0018] Beneficial effects: While ensuring the welding strength of the electrode body and the busbar, the volume and weight of the electrode body are reduced.

[0019] In one optional embodiment, a heat dissipation pipe is provided inside the heat dissipation cavity, and the inlet end and outlet end of the heat dissipation pipe extend out of the heat dissipation cavity from the first end face. The heat dissipation cavity is filled with thermally conductive adhesive, and the heat dissipation pipe is suitable for the flow of a cooling medium.

[0020] Beneficial effects: By using thermally conductive adhesive to fix the heat dissipation pipes inside the heat dissipation cavity, and realizing heat conduction between the electrode body and the cooling medium inside the heat dissipation pipes, the heat dissipation medium is used to exchange heat and cool down the electrode body, thereby improving the cooling effect of the electrode body.

[0021] Secondly, this utility model also provides a battery, comprising: The housing has an opening at at least one end; The aforementioned cover assembly is connected to the housing and seals the opening, and the housing and the cover assembly together form an accommodating space; The battery cell is disposed within the receiving space and electrically connected to the cover plate assembly. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a schematic diagram of the structure of a cover plate assembly according to an embodiment of the present utility model; Figure 2 for Figure 1 A structural schematic diagram of the cover plate assembly from another angle is shown; Figure 3 for Figure 1 Top view of the cover plate assembly shown; Figure 4 for Figure 3 A cross-sectional view along the AA direction; Figure 5 for Figure 4 A magnified view of a portion of point B in the middle; Figure 6 for Figure 4 A magnified view of a portion of point C in the middle; Figure 7 for Figure 5 The diagram shows a heat dissipation cavity containing heat dissipation pipes and thermal conductive adhesive.

[0024] Explanation of reference numerals in the attached figures: 1. Cover plate body; 11. First surface; 12. Second surface; 13. Terminal hole; 2. Terminal body; 21. First end face; 211. Busbar welding position; 22. Heat dissipation cavity; 221. First cavity section; 222. Second cavity section; 23. Cavity end wall; 24. Cavity side wall; 241. First wall section; 242. Second wall section; 243. Stepped surface; 25. Support foot; 26. Positive terminal; 27. Negative terminal; 271. Terminal base plate; 3. Pressing structure; 4. Connecting piece; 41. Positive connecting piece; 42. Negative connecting piece; 5. Seam weld mark; 6. Heat dissipation pipe; 7. Thermally conductive adhesive; 8. Upper insulating component; 9. Seam seal; 10. Lower insulating component. Detailed Implementation

[0025] 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.

[0026] The following is combined Figures 1 to 7 The following describes embodiments of the present invention.

[0027] According to an embodiment of the present invention, a cover plate assembly is provided, comprising: a cover plate body 1 having a first surface 11 and a second surface 12 disposed opposite to each other along the thickness direction, the cover plate body 1 having an electrode post hole 13 disposed through the thickness direction; an electrode post body 2 passing through the electrode post hole 13, the electrode post body 2 having a first end face 21 extending out of the first surface 11, and a heat dissipation cavity 22 being disposed inside the electrode post body 2, the heat dissipation cavity 22 being disposed through the first end face 21.

[0028] By using the cover plate assembly of this embodiment, the heat dissipation cavity 22 is opened on the electrode body 2, which can increase the contact area between the electrode body 2 and the external environment, that is, increase the heat dissipation area of ​​the electrode body 2, improve the heat dissipation effect of the electrode body 2, avoid the backflow of heat from the electrode body 2 and affect the internal environment of the battery, and improve the safety performance of the battery.

[0029] Furthermore, in one embodiment, such as Figure 5 and Figure 6 As shown, the heat dissipation cavity 22 includes a first cavity segment 221 and a second cavity segment 222 that are connected along the thickness direction. The first cavity segment 221 extends through the first end face 21, and the second cavity segment 222 is located on the side of the first cavity segment 221 away from the first end face 21. The diameter of the second cavity segment 222 is larger than the diameter of the first cavity segment 221. This arrangement, while ensuring the welding area between the electrode body 2 and the busbar, increases the opening range of the heat dissipation cavity 22, thereby improving the heat dissipation effect of the electrode body 2.

[0030] It is worth noting that the first end face 21 of the pole body 2 can be used to weld with the busbar. Therefore, in order to leave a welding area on the first end face 21, the opening range of the first cavity section 221 cannot be too large. At the same time, in order to increase the heat dissipation area of ​​the pole body 2, the opening range of the second cavity section 222 can be larger than the opening range of the first cavity section 221. This can improve the heat dissipation effect of the pole body 2 without affecting the welding of the pole body 2 and the busbar.

[0031] In one embodiment, such as Figure 3As shown, a busbar welding position 211 is formed on the portion surrounding the first cavity section 221 on the first end face 21. The diameter of the busbar welding position 211 is K, and the diameter of the first cavity section 221 is G, satisfying 0 < G ≤ K. This arrangement avoids affecting the welding of the electrode body 2 and the busbar while increasing the opening range of the first cavity section 221, thereby improving the heat dissipation effect of the electrode body 2.

[0032] It is worth noting that when the first end face 21 needs to be welded to the busbar, the opening range of the first cavity section 221 should not interfere with the welding position.

[0033] In one embodiment, such as Figure 5 and Figure 6 As shown, the portion of the electrode body 2 surrounding the first cavity segment 221 forms a cavity end wall 23, and the portion of the electrode body 2 surrounding the second cavity segment 222 forms a cavity side wall 24. The thickness of the cavity side wall 24 is not less than the thickness of the cavity end wall 23. This configuration ensures the overall structural strength of the electrode body 2 and guarantees its current-carrying capacity.

[0034] Specifically, in one embodiment, such as Figure 5 and Figure 6 As shown, the cavity sidewall 24 includes a first wall segment 241 and a second wall segment 242. The first wall segment 241 is connected to the cavity end wall 23, and the second wall segment 242 is connected to the end of the first wall segment 241 away from the cavity end wall 23. The outer peripheral surface of the second wall segment 242 extends radially beyond the outer peripheral surface of the first wall segment 241 to form a stepped surface 243 at the connection between the first wall segment 241 and the second wall segment 242. The cover plate assembly also includes a pressing structure 3, which is disposed opposite to the first surface 11 and pressed onto the stepped surface 243.

[0035] It is worth noting that the pressing structure 3 and the pole body 2 are welded together at the joint between the inner circumferential surface of the pressing structure 3 and the outer circumferential surface of the pole body 2 by laser welding.

[0036] It should be noted that by forming the stepped surface 243, the laser during laser welding can be blocked, thus avoiding ablation damage to the upper insulating component 8 located below the pressing structure 3.

[0037] Specifically, in one embodiment, such as Figure 7 As shown, the thickness of the cavity end wall 23 is A, the thickness of the first wall segment 241 is C, and the thickness of the second wall segment 242 is D, satisfying D>C≥A.

[0038] It is worth noting that, please refer to Figure 7 The thickness A of the cavity end wall 23 refers to the thickness of the cavity end wall 23 along the axial direction of the pole body 2 (i.e., Figure 4The thickness of the first wall segment 241 (in the indicated thickness direction) is C, which refers to the thickness of the first wall segment 241 in the radial direction of the pole body 2, and the thickness of the second wall segment 242 (D) refers to the thickness of the second wall segment 242 in the radial direction of the pole body 2.

[0039] Furthermore, in one embodiment, such as Figure 7 As shown, the thickness of the first wall segment 241 is C, and the thickness of the second wall segment 242 is D, satisfying 0.1mm≤DC≤1mm. By limiting the range of DC, the welding effect of the pressing structure 3 and the pole body 2 is ensured, while facilitating the processing and forming of the pole body 2 and ensuring the material utilization rate during the forming of the pole body 2.

[0040] It is worth noting that if the DC value is too small, it will be difficult to install and weld the pressing structure 3 and the electrode body 2 together. Furthermore, there is a risk of laser leakage during the welding process, which could damage the plastic coating. If the DC value is too large, it will increase the processing difficulty of the electrode body 2 and result in low material utilization during the forming process, leading to cost waste.

[0041] Optionally, DC can be any value from 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, or a value between any two of these values.

[0042] Furthermore, in one embodiment, such as Figure 7 As shown, the thickness A of the cavity end wall 23 and the thickness C of the first wall segment 241 satisfy CA ≥ 0.3 mm. This setting ensures the structural strength of the pole body 2.

[0043] It is worth noting that if the value of CA is too small, it may lead to the thickness of the first wall section 241 being too small, resulting in the structural strength of the pole body 2 being too low.

[0044] In one embodiment, such as Figure 7 As shown, the thickness of the cavity end wall 23 is A, and the thickness of the pressing structure 3 is B, satisfying B≥A. This setting ensures that the thickness of the pressing structure 3 is not less than the thickness of the cavity end wall 23, guaranteeing that the welding strength between the pressing structure 3 and the electrode body 2 meets the requirements, avoiding the risk of welding failure during battery use, improving safety, and extending service life.

[0045] Specifically, in one embodiment, such as Figure 7 As shown, the thickness of the cavity end wall 23 is A, which satisfies A≥1mm. By limiting the range of the thickness A of the cavity end wall 23, the welding strength of the pole body 2 and the busbar is guaranteed.

[0046] It is worth noting that if the value of A is too small, the weld depth that can be accommodated when welding with the busbar through the cavity end wall 23 will be small, the welding strength between the pole body 2 and the busbar will be low, and it will be easy to weld through the cavity end wall 23, affecting the welding quality.

[0047] Preferably, the thickness A of the cavity end wall 23 satisfies A≥1.5mm.

[0048] Specifically, in one embodiment, such as Figure 7 As shown, the thickness of the pressing structure 3 is B, which satisfies 1mm≤B≤5mm. By limiting the range of the thickness B of the pressing structure 3, the welding strength between the pressing structure 3 and the electrode body 2 is ensured while avoiding any impact on the volumetric energy density and gravimetric energy density of the battery.

[0049] It is worth noting that if the value of B is too small, the welding strength between the pressing structure 3 and the electrode body 2 may be insufficient, which could lead to welding failure during battery use and affect the reliability and safety of the battery. If the value of B is too large, the cover assembly may occupy too much space and be too heavy, affecting the volumetric energy density and gravimetric energy density of the battery.

[0050] Optionally, B can be any value from 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, or a value between any two of these values.

[0051] Preferably, the thickness B of the pressing structure 3 satisfies 1.5mm≤B≤3mm.

[0052] In one embodiment, such as Figure 5 and Figure 6 As shown, the cover plate assembly also includes a connecting piece 4. The connecting piece 4 is spaced apart from the second surface 12 along the thickness direction. The connecting piece 4 has a through mounting hole along the thickness direction. The outer peripheral surface of the electrode body 2 protrudes at the end away from the first end face 21 to form a support leg 25. The support leg 25 is inserted into the mounting hole. The outer peripheral surface of the support leg 25 and the connecting piece 4 are welded to the hole wall of the mounting hole by a seam weld 5. This arrangement allows the support leg 25 of the electrode body 2 to be inserted into the mounting hole, so that the electrode body 2 and the connecting piece 4 partially overlap in the thickness direction, reducing the distance between the connecting piece 4 and the second surface 12. This allows the connecting piece 4 to fully occupy the thickness space of the cover plate body 1, leaving more space for the battery cell and improving the volumetric energy density of the battery.

[0053] Furthermore, in one embodiment, such as Figures 5 to 7 As shown, the thickness of the support leg 25 is E, and the thickness of the connecting piece 4 is T, satisfying E≥T.

[0054] It is worth noting that, such as Figure 5 and Figure 6 As shown, the cover plate body 1 typically has two electrode bodies 2, namely a positive electrode 26 and a negative electrode 27. The positive electrode 26 is connected to a positive electrode connecting piece 41, and the negative electrode 27 is connected to a negative electrode connecting piece 42. The positive electrode connecting piece 41 is generally made of aluminum, and the negative electrode connecting piece 42 is generally made of copper. Copper has better conductivity than aluminum, that is, copper has a greater current carrying capacity than aluminum. Therefore, the thickness I of the positive electrode connecting piece 41 can be not less than the thickness J of the negative electrode connecting piece 42, that is, I ≥ J.

[0055] It is understandable that when connecting piece 4 is the positive electrode connecting piece 41, T=I; when connecting piece 4 is the negative electrode connecting piece 42, T=J.

[0056] Furthermore, the thickness I of the positive electrode connecting piece 41, the thickness J of the negative electrode connecting piece 42, and the thickness E of the support leg 25 satisfy E≥I≥J.

[0057] In one embodiment, such as Figures 5 to 7 As shown, the thickness of the support 25 is E, and the thickness of the cavity end wall 23 is A, satisfying A≥E. This configuration ensures the welding strength of the pole body 2 and the busbar while reducing the volume and weight of the pole body 2.

[0058] It is worth noting that the cavity end wall 23 needs to be welded to the busbar, while the support 25 does not need to be welded and only needs to be welded to the connecting piece 4. Therefore, the thickness of the support 25 can be kept within the thickness of the cavity end wall 23. This ensures that the cavity end wall 23 has sufficient thickness for welding and avoids the support 25 being too thick, which would affect the volumetric energy density and gravimetric energy density of the battery.

[0059] Additionally, it is worth noting that, such as Figure 6 As shown, the negative electrode post 27 is typically a copper-aluminum composite post. Specifically, the negative electrode post 27 also includes a post base plate 271. The end of the second wall segment 242 away from the first wall segment 241 is connected to the post base plate 271. The diameter of the post base plate 271 is larger than the outer diameter of the second wall segment 242, so that the post base plate 271 extends beyond the second wall segment 242 and forms the aforementioned support leg 25. The thickness of the part where the post base plate 271 connects to the second wall segment 242 is F, satisfying F≥E.

[0060] It should be further explained that the copper-aluminum composite electrode post can be connected to the second wall section 242 and the electrode post base plate 271 using friction welding, or it can be directly formed using methods such as rotary riveting of copper-aluminum composite materials. When directly forming the copper-aluminum composite material, the surface of the support leg 25 will be covered with a layer of aluminum. This aluminum layer needs to be removed, along with a portion of the copper, to ensure that the aluminum layer is completely removed. This prevents the copper-aluminum composite material from being immersed in a battery containing electrolyte, which would form a galvanic cell, corrode the aluminum, and further corrode and damage the negative electrode post 27. Therefore, in the negative electrode post 27, F ≥ E.

[0061] In one embodiment, such as Figure 7 As shown, a heat dissipation pipe 6 is provided inside the heat dissipation cavity 22. The inlet and outlet ends of the heat dissipation pipe 6 extend out of the heat dissipation cavity 22 from the first end face 21. The heat dissipation cavity 22 is filled with thermally conductive adhesive 7, and the heat dissipation pipe 6 is suitable for the flow of cooling medium. The heat dissipation pipe 6 is fixed in the heat dissipation cavity 22 by the thermally conductive adhesive 7, and heat conduction is realized between the electrode body 2 and the cooling medium in the heat dissipation pipe 6. Thus, the cooling medium exchanges heat and cools the electrode body 2, improving the cooling effect of the electrode body 2. That is, the heat of the electrode body 2 is discharged through the thermally conductive adhesive 7-heat dissipation pipe 6-cooling medium.

[0062] It is worth noting that the cooling medium can be ethylene glycol, water, or a mixture of ethylene glycol and water.

[0063] It should be noted that when a heat dissipation pipe 6 is installed in the heat dissipation cavity 22, since the heat dissipation pipe 6 needs to enter and exit the heat dissipation cavity 22 through the first cavity section 221, the diameter of the first cavity section 221 should be no less than twice the diameter of the heat dissipation pipe 6 when necessary.

[0064] In one embodiment, such as Figure 5 and Figure 6 As shown, the cover plate assembly also includes an upper insulating member 8, which is disposed between the pressing structure 3 and the first surface 11, and a portion of the upper insulating member 8 is inserted into the pole hole 13 and located between the hole wall of the pole hole 13 and the outer wall of the pole body 2.

[0065] In one embodiment, such as Figure 5 and Figure 6 As shown, the cover assembly also includes a seal 9, which is disposed around the outer periphery of the second wall section 242 and located on the support leg 25. The side of the seal 9 away from the support leg 25 is pressed by the cover body 1 and the upper insulating member 8.

[0066] In one embodiment, such as Figure 5 and Figure 6As shown, the cover plate assembly also includes a lower insulating member 10, which is fitted to the second surface 12. A portion of the lower insulating member 10 is located between the second surface 12 and the connecting piece 4, and between the second surface 12 and the support leg 25.

[0067] According to an embodiment of the present invention, another aspect provides a battery, comprising: a housing having an opening at at least one end; a cover assembly connected to the housing and sealing the opening, the housing and the cover assembly forming an accommodating space; and a battery cell disposed within the accommodating space and electrically connected to the cover assembly.

[0068] 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 cover plate assembly, characterized in that, include: The cover plate body (1) has a first surface (11) and a second surface (12) arranged opposite to each other along the thickness direction. The cover plate body (1) has a pole hole (13) that is arranged through the thickness direction. The pole body (2) is inserted through the pole hole (13). The pole body (2) has a first end face (21) extending out of the first surface (11). A heat dissipation cavity (22) is provided inside the pole body (2). The heat dissipation cavity (22) is provided through the first end face (21).

2. The cover plate assembly according to claim 1, characterized in that, The heat dissipation cavity (22) includes a first cavity segment (221) and a second cavity segment (222) that are connected along the thickness direction. The first cavity segment (221) is disposed through the first end face (21), and the second cavity segment (222) is disposed on the side of the first cavity segment (221) away from the first end face (21). The diameter of the second cavity segment (222) is larger than the diameter of the first cavity segment (221).

3. The cover plate assembly according to claim 2, characterized in that, A busbar welding position (211) is formed on the portion of the first end face (21) surrounding the first cavity segment (221). The diameter of the busbar welding position (211) is K, and the diameter of the first cavity segment (221) is G, satisfying 0 < G ≤ K.

4. The cover plate assembly according to claim 2 or 3, characterized in that, The pole body (2) forms a cavity end wall (23) around the first cavity segment (221), and forms a cavity side wall (24) around the second cavity segment (222). The thickness of the cavity side wall (24) is not less than the thickness of the cavity end wall (23).

5. The cover plate assembly according to claim 4, characterized in that, The cavity sidewall (24) includes a first wall segment (241) and a second wall segment (242). The first wall segment (241) is connected to the cavity end wall (23). The second wall segment (242) is connected to the end of the first wall segment (241) away from the cavity end wall (23). The outer peripheral surface of the second wall segment (242) extends radially beyond the outer peripheral surface of the first wall segment (241) to form a stepped surface (243) at the connection between the first wall segment (241) and the second wall segment (242). The cover plate assembly also includes a pressing structure (3). The pressing structure (3) is disposed opposite to the first surface (11) and pressed onto the stepped surface (243).

6. The cover plate assembly according to claim 5, characterized in that, The thickness of the cavity end wall (23) is A, the thickness of the first wall segment (241) is C, and the thickness of the second wall segment (242) is D, satisfying D>C≥A; and / or, The thickness of the cavity end wall (23) is A, and the thickness of the pressing structure (3) is B, satisfying B≥A; and / or, The thickness of the first wall segment (241) is C, and the thickness of the second wall segment (242) is D, satisfying 0.1mm ≤ DC ≤ 1mm; and / or, The thickness of the cavity end wall (23) is A, satisfying A≥1mm; and / or, The thickness of the pressing structure (3) is B, which satisfies 1mm≤B≤5mm.

7. The cover plate assembly according to claim 4, characterized in that, The cover plate assembly also includes a connecting piece (4), which is spaced apart from the second surface (12) along the thickness direction. The connecting piece (4) has a through mounting hole along the thickness direction. The outer peripheral surface of the pole body (2) has a protruding support (25) at the end away from the first end face (21). The support (25) is inserted into the mounting hole. The outer peripheral surface of the support (25) and the connecting piece (4) are welded around the hole wall of the mounting hole by a seam weld (5).

8. The cover plate assembly according to claim 7, characterized in that, The thickness of the support (25) is E, and the thickness of the cavity end wall (23) is A, satisfying A≥E; and / or, The thickness of the support leg (25) is E, and the thickness of the connecting piece (4) is T, satisfying E≥T.

9. The cover plate assembly according to any one of claims 1 to 3, characterized in that, The heat dissipation cavity (22) is provided with a heat dissipation pipe (6), the inlet end and outlet end of the heat dissipation pipe (6) extend out of the heat dissipation cavity (22) from the first end face (21), the heat dissipation cavity (22) is filled with thermally conductive adhesive (7), and the heat dissipation pipe (6) is suitable for the flow of cooling medium.

10. A battery, characterized in that, include: The housing has an opening at at least one end; The cover plate assembly according to any one of claims 1 to 9 is connected to the housing and seals the opening, wherein the housing and the cover plate assembly enclose a receiving space; The battery cell is disposed within the receiving space and electrically connected to the cover plate assembly.

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