Secondary battery top cover and secondary battery

Abstract

A secondary battery top cover, comprising a cover plate with a pole hole formed therethrough, an inner insulating member attached to the lower surface of the cover plate, an outer insulating member attached to the upper surface of the cover plate, a connecting block supported on the outer insulating member, a connecting piece with a fixing hole formed therethrough and attached to the inner insulating member, a connecting post connecting the connecting block and the connecting piece, and a sealing ring sleeved on the connecting post, the connecting block is formed with a riveting hole therethrough, the connecting post comprises a post body inserted into the riveting hole and a lower protruding portion protruding downward from the bottom of the post body, the post body is integrally welded with the riveting hole, the lower protruding portion is accommodated in the fixing hole and is welded and fixed, and the connecting post comprises an aluminum layer welded with the connecting block and a copper layer wrapped around the bottom of the aluminum layer and welded with the connecting piece. The application has stable electrical connection performance, can reduce the weight of the product, and has low manufacturing cost.

Description

Technical Field

[0001] This application relates to the field of batteries, and more particularly to a secondary battery top cover and a secondary battery. Background Technology

[0002] Secondary batteries are widely used in daily life as energy storage carriers or to provide power to electrical devices such as electric vehicles and energy storage projects. A secondary battery generally includes a metal casing, battery cells encapsulated within the casing, electrolyte, and a battery top cover that seals the casing and leads out the electrodes. The battery top cover has various structural forms and meets requirements for sealing and explosion-proof performance. A commonly used battery top cover structure uses a riveting block, which includes a cover plate with through-holes forming the electrode posts, an outer insulating component located on the upper side of the cover plate, a riveting block located above the outer insulating component, an inner insulating component attached to the lower side of the cover plate, and electrode posts that pass through the cover plate and riveting block from below and are riveted to the riveting block. The top of the electrode post is fixed to the riveting block by riveting, and a sealing ring is clamped between the electrode post and the cover plate for sealing.

[0003] In battery connection technology, aluminum is preferably used as the current collector for the positive electrode, while copper is preferably used as the current collector for the negative electrode. The connecting piece for the current collector needs to be made of the same metal as the current collector. In the negative electrode solution mentioned above, the connecting piece and the electrode post are integrally formed, and the entire assembly needs to be made of copper, resulting in a large amount of copper used, increased weight, and higher material costs. To solve this problem, Chinese Patent No. 201921041367.2 discloses a top cover. The negative electrode top cover assembly of this top cover includes a negative electrode substrate, a negative electrode post, a negative electrode connecting block, a negative electrode upper support, a negative electrode lower support, and a negative electrode sealing element. The negative electrode post passes through the negative electrode sealing element, the negative electrode lower support, the negative electrode substrate, and the negative electrode upper support in sequence before connecting to the negative electrode connecting block. The negative electrode post includes a negative electrode base (i.e., connecting piece), a negative electrode rivet, and an auxiliary welding piece. The negative electrode connecting block is riveted to the negative electrode rivet, and the auxiliary welding piece is laser welded to the negative electrode base. This solution uses aluminum for the negative electrode post, and an auxiliary welding piece of the same material is used to cover the bottom of the rivet and weld it to the negative electrode base. The rivet and the negative electrode base are limited by the flange edge, which causes some problems with the stability of the electrical connection between them. Utility Model Content

[0004] Therefore, it is necessary to provide a secondary battery top cover and secondary battery that have stable electrical connection, are lightweight and low cost.

[0005] To solve the above-mentioned technical problems, this application provides a secondary battery top cover, including a cover plate through which terminal holes are formed, an inner insulating member attached to the lower surface of the cover plate, an outer insulating member attached to the upper surface of the cover plate, a connecting block supported on the outer insulating member, a connecting piece attached to the inner insulating member and having a through fixing hole, a connecting post connecting the connecting block and the connecting piece, and a sealing ring sleeved on the connecting post. The connecting block has a through riveting hole, and the connecting post includes a column portion inserted into the riveting hole and a lower protrusion protruding downward from the bottom of the column portion. The column portion is welded to the riveting hole at the joint, and the lower protrusion is accommodated in the fixing hole and welded and fixed. The connecting post includes an aluminum layer welded to the connecting block and a copper layer covering the bottom of the aluminum layer and welded to the connecting piece.

[0006] Preferably, the connecting column is formed by stamping a copper-aluminum composite plate and a stepped portion is formed between the lower protrusion and the column body portion, and the top surface of the connecting piece abuts against the stepped portion; the copper-aluminum composite plate is formed by pressing softened or molten aluminum material onto a copper material layer.

[0007] Preferably, the copper layer is first stamped to form a groove structure, and then softened or molten aluminum is filled into the groove structure and the upper surface of the copper layer to form the copper-aluminum composite plate.

[0008] Preferably, the connecting block has a second recessed groove formed around the rivet hole, and the top surface of the column portion is flush with the bottom surface of the second recessed groove and welded at the joint so that the welding position does not extend beyond the top surface of the connecting block.

[0009] Preferably, the connecting piece includes a piece body, the fixing hole is formed through the piece body, the bottom surface of the piece body is recessed upward at the periphery of the fixing hole to form a concave ring, the bottom surface of the lower protrusion is flush with the bottom surface of the concave ring, the lower protrusion is welded to the joint gap of the fixing hole, and the weld point produced by the welding does not extend downward beyond the height of the concave ring, that is, does not extend beyond the lower surface of the piece body.

[0010] Preferably, the external insulating component includes an insulating plate body attached to the upper surface of the cover plate, an outer wall protruding upward from the periphery of the insulating plate body to partially surround the outer edge of the connecting block, and a through hole formed through the insulating plate body. A lower edge ring body is formed by protruding downward from the periphery of the through hole. The lower edge ring body is pressed into the inner side of the pole hole of the cover plate. There is a gap between the lower edge ring body and the pole portion. The top end of the inner ring of the sealing ring is inserted into the gap between the lower edge ring body and the pole portion.

[0011] Preferably, the inner insulating member includes an adhesive body attached to the lower surface of the cover plate, a through hole formed through the adhesive body, and a receiving cavity formed on the bottom surface of the adhesive body for receiving the connecting piece. The receiving cavity has a surrounding wall formed on its outer periphery. The outer ring of the sealing ring is located in the radial direction between the inner wall surface of the through hole and the outer surface of the column portion, and the outer ring is clamped between the connecting piece and the lower surface of the cover plate in the vertical direction.

[0012] Preferably, the cover plate is formed by pressing downward on both sides of the pole hole to form a first positioning structure. The first positioning structure includes a first positioning recess recessed from the upper surface of the cover plate and a first positioning protrusion protruding from the lower surface of the cover plate. The inner insulating member is formed by recessing downward corresponding to the first positioning protrusion to form a second positioning structure. The second positioning structure includes a second positioning recess into which the first positioning protrusion is inserted and a second positioning protrusion protruding from the bottom surface of the inner insulating member. The outer insulating member is formed by protruding from the first positioning recess and being inserted into the first positioning recess. The connecting piece is provided with a third positioning recess at the position corresponding to the second positioning protrusion.

[0013] To address the aforementioned technical problems, this application also provides a secondary battery, including a housing, a cell unit encapsulated within the housing, and the aforementioned secondary battery top cover, wherein the secondary battery top cover is used to seal the housing.

[0014] The secondary battery top cover and secondary battery of this application are made by adding a connecting post with an aluminum layer and a copper layer, and connecting blocks and connecting pieces of different metal materials are connected through the connecting post to complete welding between the same metal materials; at the same time, the upper and lower sides of the connecting post are fixed by welding to ensure the stability of the electrical connection; the use of copper-aluminum composite plate greatly reduces the amount of copper used, reduces weight and reduces material cost. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0016] Example 1

[0017] Figure 1 This is a perspective view of the top cover of the secondary battery according to Embodiment 1 of this application;

[0018] Figure 2 This is an exploded perspective view of the top cover of the secondary battery according to Embodiment 1 of this application;

[0019] Figure 3 For along Figure 2 The cross-sectional view shown by the dashed line AA;

[0020] Figure 4 This is a perspective view of the outer insulating component of the secondary battery top cover according to Embodiment 1 of this application;

[0021] Figure 5 This is a perspective view of the inner insulating component of the secondary battery top cover according to Embodiment 1 of this application.

[0022] Figure 6 For along Figure 1 The cross-sectional view shown by the dashed line BB;

[0023] Example 2

[0024] Figure 7 This is a diagram showing the combination of the terminal post and connecting piece of the secondary battery top cover according to Embodiment 2 of this application;

[0025] Figure 8 This is a cross-sectional view of the secondary battery top cover before riveting in Embodiment 2 of this application;

[0026] Figure 9 This is a cross-sectional view of the secondary battery top cover after riveting according to Embodiment 2 of this application;

[0027] Example 3

[0028] Figure 10 This is a cross-sectional view of the top cover of the secondary battery according to Embodiment 3 of this application.

[0029] Explanation of reference numerals in the attached figures

[0030] Cover plate -10; Pole post hole -11; First positioning structure -12; First positioning recess -121; First positioning protrusion -122; Connecting block -20; Riveting hole -21; Second recessed groove -211; First recessed groove -212; Outer insulation component -30; Isolation plate body -31; Outer wall -32; Receiving cavity -33; Through hole -34; Lower edge ring body -35; Third positioning protrusion -36; Connecting piece -40; Piece body -41; Fixing hole -42; Third positioning recess -4 3; Concave ring - 44; Inner insulation component - 50; Fitting body - 51; Through hole - 52; Second positioning structure - 53; Second positioning recess - 531; Second positioning protrusion - 532; Surrounding wall - 54; Receiving cavity - 55; Sealing ring - 60; Inner ring body - 61; Sealing hole - 62; Outer ring body - 63; Connecting post - 90; Aluminum layer - 901; Copper layer - 902; Post body - 91; Lower protrusion - 92; Stepped part - 93; Flange edge - 94; Riveting groove - 95. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.

[0032] This application is based on Figure 1 The X direction is the horizontal direction, the Y direction is the vertical direction, and the Z direction is the vertical direction above.

[0033] Example 1

[0034] Please see Figures 1 to 6 As shown, the secondary battery top cover of this embodiment includes a cover plate 10, an inner insulating member 50 attached to the lower surface of the cover plate 10, an outer insulating member 30 attached to the upper surface of the cover plate 10, a connecting block 20 mounted on the outer insulating member 30, a connecting piece 40 placed on the inner insulating member 50, a connecting post 90 that fixes the connecting block 20 and the connecting piece 40 together, and a sealing ring 60 clamped between the cover plate 10, the connecting post 90 and the connecting piece 40.

[0035] Please refer to this carefully. Figure 2 , Figure 3 As shown, the cover plate 10 is made of aluminum alloy, stainless steel, or titanium alloy. If stainless steel or titanium alloy is used, the cover plate 10 is thinner, while if aluminum alloy is used, the cover plate is relatively thicker. Stainless steel and titanium alloy have higher melting points, offering better safety. However, stainless steel is more difficult to process than aluminum alloy, making it generally unsuitable for machining complex structures on the cover plate 10, as this would increase manufacturing costs. Titanium alloy is even more difficult to process and has higher material costs, generally used in the aerospace field. Aluminum alloy is currently the material widely used in automotive power batteries and energy storage batteries, but due to its low melting point, it is prone to burning through and destroying the entire battery pack in a short time once a fire starts, resulting in a short explosion time and insufficient escape time for vehicle occupants. Stainless steel not only reduces material costs and improves space utilization but also enhances product safety, extending the time before a large-scale fire or explosion, providing more time for occupants to escape.

[0036] The cover plate 10 includes a through-hole 11 and a first positioning structure 12 formed by pressing downwards on both sides of the through-hole 11 in the transverse direction. The first positioning structure 12 includes a first positioning recess 121 formed inwardly from the upper surface of the cover plate 10 and a first positioning protrusion 122 formed protruding from the lower surface of the cover plate 10. The first positioning recess 121 and the first positioning protrusion 122 are formed by simultaneously pressing the first positioning structure 12 on both the outer and inner sides.

[0037] The connecting piece 40 is made of copper alloy sheet and includes a piece body 41, a fixing hole 42 formed through the piece body 41 in the vertical direction, and third positioning recesses 43 formed by stamping on both sides of the fixing hole 42 in the lateral direction. The third positioning recesses 43 are formed on the upper surface of the piece body 41, the lower surface of the piece body 41 is flat and does not have any protrusions, and the third positioning recesses 43 are opened laterally on the outer side in a notch-shaped shape. A concave ring 44 is formed by recessing upward at the periphery of the fixing hole 42 on the lower surface of the piece body 41, and the bottom surface of the concave ring 44 is higher than the bottom surface of the piece body 41.

[0038] Key references Figure 2 , Figure 3 , Figure 5 As shown, the inner insulating member 50 includes an adhesive body 51 attached to the lower surface of the cover plate 10, a through hole 52 formed through the adhesive body 51, a second positioning structure 53 formed on both sides of the through hole 52, and a receiving cavity 55 formed on the lower surface of the adhesive body 51 and surrounding the through hole 52. The second positioning structure 53 includes a second positioning recess 531 recessed downward from the upper surface of the adhesive body 51 and a second positioning protrusion 532 protruding from the lower surface of the adhesive body 51. The second positioning protrusion 532 is also surrounded within the receiving cavity 55. The receiving cavity 55 is formed by a surrounding wall 54 protruding from the lower surface of the adhesive body 51, and the lower surface of the second positioning protrusion 532 does not extend beyond the bottom surface of the surrounding wall 54. The connecting piece 40 is pressed into the receiving cavity 55, and the periphery of the connecting piece 40 is limited by the surrounding wall 54. The third positioning recess 43 of the connecting piece 40 engages with the second positioning protrusion 532 to prevent rotation. The second positioning protrusion 532 is integrally connected to the surrounding wall 54 to enhance its strength.

[0039] Please continue reading. Figures 2 to 4 As shown, the outer insulating member 30 includes an insulating plate 31, an outer peripheral wall 32 protruding upward from the upper surface of the insulating plate 31, a receiving cavity 33 formed by the insulating plate 31 and the outer peripheral wall 32, and a through hole 34 formed through the insulating plate 31. The bottom surface of the insulating plate 31 protrudes downward to form a third positioning protrusion 36, and the edge of the through hole 34 extends downward to form a lower edge ring 35.

[0040] The sealing ring 60 includes an inner ring body 61, an outer ring body 63 extending radially outward from the lower side of the inner ring body 61, and a sealing hole 62 forming through the inner ring body 61. The outer diameter of the outer ring body 63 is larger than the outer diameter of the inner ring body 61, and the inner ring body 61 extends upward from the upper surface of the outer ring body 63.

[0041] A rivet hole 21 is formed through the middle of the connecting block 20. A second recessed groove 211 and a first recessed groove 212 are formed on the surface of the connecting block 20 from the periphery of the rivet hole 21. The bottom surface of the second recessed groove 211 is higher than the bottom surface of the first recessed groove 212, and the inner diameter of the second recessed groove 211 is larger than the inner diameter of the first recessed groove 212. The inner diameter of the first recessed groove 212 is larger than the inner diameter of the rivet hole 21.

[0042] The connecting post 90 includes a post body 91, a downwardly protruding portion 92 extending from the bottom of the post body 91, a flange edge 94 extending radially from the outer edge of the top of the post body 91, and a stepped portion 94 formed on the lower surface of the post body 91 and radially outward of the downwardly protruding portion 92. If the connecting post 90 is used as a positive electrode material, it is made entirely of aluminum. If the connecting post 90 is used as a negative electrode, it includes an aluminum layer 901 and a copper layer 902 covering the bottom surface of the aluminum layer 901, the copper layer 902 wrapping around the bottom surfaces of the downwardly protruding portion 92 and the stepped portion 93.

[0043] This embodiment uses the connecting post 90 as the negative electrode. The connecting post 90 is formed by stamping, that is, stamping several connecting posts 90 onto a metal sheet. The metal sheet is formed by first selecting copper material of a certain thickness, and then pressing softened or molten aluminum material onto the surface of the copper material to form a copper-aluminum composite plate. Subsequently, the copper-aluminum composite plate is stamped into several connecting posts 90 by stamping. In this scheme, the copper material layer 902 on the outer side of the lower protrusion 92 will become thinner or missing, but the copper material layer 902 on the bottom surface of the lower protrusion 92 can remain intact and achieve the required performance.

[0044] Alternatively, the copper sheet can be pre-stamped to form a groove structure, and then softened or molten aluminum can be pressed onto the groove structure and the surface of the copper to form a copper-aluminum composite plate with a lower protrusion 92 and a step 93. The copper-aluminum composite plate can then be cut into several connecting columns 90.

[0045] Key references Figure 6 As shown, the following will focus on the assembly method of the secondary battery top cover in this embodiment:

[0046] First, the connecting post 90 is inserted from top to bottom into the riveting hole 21 of the connecting block 20. The flange edge 94 of the connecting post 90 is supported on the surface of the first recessed groove 212, and the upper surface of the flange edge 94 is flush with the bottom surface of the second recessed groove 211. The connecting post 90 and the connecting block 20 are welded and fixed along the joint between the flange edge 94 and the edge of the second recessed groove 211 and sealed. Then, the outer insulating component 30 is assembled onto the outer surface of the cover plate 10. The third positioning protrusion 36 of the outer insulating component 30 enters the first positioning recess 121 on the outer surface of the cover plate 10, and the lower edge ring 35 is inserted into the edge of the pole hole 11. The inner insulating component 50 is attached to the inner surface of the cover plate 10 and fixed to the inner surface of the cover plate 10 by snap-fit ​​or adhesive. The first positioning protrusion 122 enters the second positioning recess 531 on the surface of the inner insulating component 50 for limitation. The inner diameter of the through hole 52 of the inner insulating member 50 is much larger than the pole hole 11 of the cover plate 10 so that at least a portion of the inner surface of the cover plate 10 within the through hole 52 is exposed outside the inner insulating member 50; the assembly of the connecting block 20 and the connecting post 90 is positioned on the outer insulating member 20, the connecting block 20 is at least partially surrounded by the receiving cavity 33, and the lower portion of the connecting post 90 passes through the through hole 34, the pole hole 11, and the through hole 52; the sealing ring 60 is fitted from bottom to top onto the column portion 91, the top of the inner ring 61 abuts against the bottom surface of the connecting block 20 and wraps around the outer periphery of the column portion 91, the outer ring 63 is located within the through hole 52 of the inner insulating member 50 and the upper surface of the outer ring 63 is attached to the lower surface of the cover plate 10; finally, the... The connecting piece 40 is inserted into the receiving cavity 55 on the bottom surface of the inner insulating member 50. The second positioning protrusion 532 of the inner insulating member 50 is engaged in the third positioning recess 43 of the connecting piece 40. The bottom surface of the outer ring 63 of the sealing ring 60 is supported on the upper surface of the connecting piece 40. The lower protrusion 92 is inserted into the fixing hole 42 of the connecting piece 40, and the upper surface of the connecting piece 40 is limited to the step portion 93. The connecting piece 40 and the connecting block 20 are pressed together, so that the bottom surface of the concave ring 44 of the connecting piece 40 is flush with the bottom surface of the lower protrusion 92. At this time, the inner ring 61 of the sealing ring 60 is squeezed and clamped by the bottom surface of the connecting piece 40 and the connecting block 20, and the outer ring 63 is squeezed and clamped by the inner surface of the cover plate 10 and the connecting piece 40. The outer contour of the connecting piece 40 is consistent with the receiving cavity 55 of the inner insulating member 50, so that the connecting piece 40 is confined within the receiving cavity 55. After pressing the connecting block 20 and the connecting piece 40 together, continuous welding is performed at the joint between the connecting piece 40 and the lower protrusion 92 to fix the connecting post 90 and the connecting piece 40 together and form a weld ring S.

[0047] In this embodiment, the inner ring 61 of the sealing ring 60 achieves the seal between the bottom surface of the connecting block 20, the outer peripheral surface of the connecting post 90 and the surface of the connecting piece 40, and the outer ring 63 achieves the seal between the inner surface of the cover plate 10 and the surface of the connecting piece 40, thus achieving double waterproofing, and the waterproofing no longer depends on the welding seal of the welding ring S.

[0048] In this embodiment, a connecting post 90 with an aluminum layer 901 and a copper layer 902 is added, and the connecting block 20 and connecting piece 40 of different metal materials are connected through the connecting post 90 to complete welding between the same metal materials; at the same time, the upper and lower sides of the connecting post 90 are fixed by welding to ensure the stability of the electrical connection.

[0049] Example 2

[0050] Please see Figures 7 to 9 As shown, the difference between this embodiment and embodiment one is that the structure of the flange edge 94 of the connecting column 90 is eliminated, so that the outer diameter of the column body 91 remains consistent. The following differences exist in the assembly process: First, the connecting piece 40 is welded and fixed to the connecting column 90; then, the sealing ring 60 is fitted onto the outside of the column body 91 from top to bottom; then, the outer insulating component 30 and the inner insulating component 50 are respectively installed on the outer and inner surfaces of the cover plate 10; the assembly of the connecting piece 40 and the connecting column 90 is inserted from bottom to top, so that the column body 91 passes through the through hole 52, the pole hole 11, the through hole 34, and the riveting hole 21; finally, the top of the column body 91 is riveted to expand the outer diameter of the column body 91 to support the bottom surface of the first recessed groove 212, and the column body 91 is welded and fixed to the second recessed groove 211. A riveting groove 95 is formed at the top of the connecting column 90 during riveting.

[0051] The remaining structure of Embodiment 2 is basically the same as that of Embodiment 1. The design of the concave ring 44 of the connecting piece 40 in Embodiments 1 and 2 serves to ensure that the welding of the connecting piece 40 and the second column 202 is carried out within the concave ring 44, so that the weld point formed during welding will not protrude beyond the bottom surface of the piece 41 of the connecting piece 40, and the bottom surface of the piece 41 remains smooth and flat.

[0052] In Embodiment 2, a riveting process is added between the connecting column 90 and the connecting block 20 during welding, making the connection between the connecting column 90 and the connecting block 20 more stable and reliable.

[0053] Example 3

[0054] Please see Figure 7 , Figure 10As shown, the difference between this embodiment and embodiment one is that: the structure of the flange edge 94 of the connecting column 90 is removed, so that the outer diameter of the column body 91 remains consistent; the first recessed groove 212 of the connecting block 20 is removed, and only the first recessed groove 212 is retained; the following differences exist in the assembly: first, the connecting piece 40 and the connecting column 90 are combined and welded together; then, the sealing ring 60 is fitted onto the outside of the column body 91 from top to bottom; then, the outer insulating component 30 and the inner insulating component 50 are respectively installed on the outer surface and inner surface of the cover plate 10; the combination of the connecting piece 40 and the connecting column 90 is installed from bottom to top, so that the column body 91 passes through the through hole 52, the pole hole 11, the through hole 34, and the riveting hole 21; at this time, the top surface of the column body 91 is flush with the bottom surface of the second recessed groove 211, and the column body 91 and the second recessed groove 211 are joined and welded together.

[0055] This application also includes a secondary battery, the secondary battery comprising a housing, a cell unit encapsulated within the housing, and a top cover of the secondary battery that closes the housing and is electrically connected to the cell unit.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The above embodiments only illustrate preferred implementations of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A secondary battery top cover, comprising a cover plate through which terminal holes are formed, an inner insulating member attached to the lower surface of the cover plate, an outer insulating member attached to the upper surface of the cover plate, a connecting block supported on the outer insulating member, a connecting piece attached to the inner insulating member and having a through fixing hole, a connecting post connecting the connecting block and the connecting piece, and a sealing ring sleeved on the connecting post, characterized in that, The connecting block has a through-hole for riveting. The connecting post includes a column portion inserted into the riveting hole and a downward protrusion formed from the bottom of the column portion. The column portion is welded to the riveting hole to form a whole. The downward protrusion is accommodated in the fixing hole and welded to fix it. The connecting post includes an aluminum layer welded to the connecting block and a copper layer covering the bottom of the aluminum layer and welded to the connecting piece.

2. The secondary battery top cover as described in claim 1, characterized in that, The connecting column is formed by stamping a copper-aluminum composite plate and a stepped portion is formed between the lower protrusion and the column body. The top surface of the connecting piece abuts against the stepped portion. The copper-aluminum composite plate is formed by pressing softened or molten aluminum onto a copper layer.

3. The secondary battery top cover as described in claim 2, characterized in that, The copper layer is first stamped to form a groove structure, and then softened or molten aluminum is filled into the groove structure and the upper surface of the copper layer to form the copper-aluminum composite plate.

4. The secondary battery top cover as described in claim 2, characterized in that, The connecting block has a second recessed groove formed around the rivet hole. The top surface of the column is flush with the bottom surface of the second recessed groove and they are welded together so that the welding position does not exceed the top surface of the connecting block.

5. The secondary battery top cover as described in claim 2, characterized in that, The connecting piece includes a piece body, the fixing hole is formed through the piece body, the bottom surface of the piece body is recessed upward at the periphery of the fixing hole to form a concave ring, the bottom surface of the lower protrusion is flush with the bottom surface of the concave ring, the lower protrusion is welded to the joint gap of the fixing hole, and the weld point produced by the welding does not extend downward beyond the height of the concave ring, that is, does not extend beyond the lower surface of the piece body.

6. The secondary battery top cover as described in claim 5, characterized in that, The external insulating component includes an insulating plate body attached to the upper surface of the cover plate, an outer wall protruding upward from the periphery of the insulating plate body to partially surround the outer edge of the connecting block, and a through hole formed through the insulating plate body. A lower edge ring body is formed by protruding downward from the periphery of the through hole. The lower edge ring body is pressed into the inner side of the pole hole of the cover plate. There is a gap between the lower edge ring body and the pole portion. The top end of the inner ring body of the sealing ring is inserted into the gap between the lower edge ring body and the pole portion.

7. The secondary battery top cover as described in claim 6, characterized in that, The inner insulating component includes an adhesive body that adheres to the lower surface of the cover plate, a through hole formed through the adhesive body, and a receiving cavity formed on the bottom surface of the adhesive body for accommodating the connecting piece. A surrounding wall is formed on the outer periphery of the receiving cavity. The outer ring of the sealing ring is located in the radial direction between the inner wall surface of the through hole and the outer surface of the column portion, and the outer ring is clamped between the connecting piece and the lower surface of the cover plate in the vertical direction.

8. The secondary battery top cover as described in claim 7, characterized in that, The cover plate is formed by pressing downward on both sides of the pole hole to form a first positioning structure. The first positioning structure includes a first positioning recess recessed from the upper surface of the cover plate and a first positioning protrusion protruding from the lower surface of the cover plate. The inner insulating member is formed by recessing downward corresponding to the first positioning protrusion to form a second positioning structure. The second positioning structure includes a second positioning recess into which the first positioning protrusion is inserted and a second positioning protrusion protruding from the bottom surface of the inner insulating member. The outer insulating member is formed by protruding from the first positioning recess and being inserted into the first positioning recess. The connecting piece is provided with a third positioning recess at the position corresponding to the second positioning protrusion.

9. A secondary battery, characterized in that, It includes a housing, a battery cell unit encapsulated within the housing, and a secondary battery top cover as described in claim 1, wherein the secondary battery top cover is used to seal the housing.

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