Cover plate assembly and cylindrical lithium battery

Abstract

The utility model is applicable to the field of cylindrical lithium batteries, and discloses a cover plate assembly for a cylindrical lithium battery and the cylindrical lithium battery, the cover plate assembly comprises a cover plate, a positive pole column, a first upper plastic part, a negative pole column and a second upper plastic part, the positive pole column penetrates through a first hole in the cover plate, the negative pole column penetrates through a second hole in the positive pole column, and the first upper plastic part and the second upper plastic part are arranged on the cover plate. The first upper plastic part is arranged between the cover plate and the positive pole, and the second upper plastic part is arranged between the positive pole and the negative pole. The positive pole column, the negative pole column and the cover plate are insulated from one another through the plastic part, so that the shell of the cylindrical lithium battery comprising the cover plate assembly is not electrified; meanwhile, only one first hole is formed in the cover plate, and the liquid leakage risk of the cylindrical lithium battery can be reduced through fewer holes in the cover plate; the positive pole and the negative pole are arranged on one side of the cover plate, so that the total height of the cylindrical lithium battery is reduced, the space utilization rate of a battery pack is relatively high, and the overall energy density is improved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to a cover assembly and a cylindrical lithium battery. Background Art

[0002] In the related art, currently in large cylindrical batteries, generally the negative electrode is electrically connected to the steel shell, making the steel shell body charged. And currently, cylindrical batteries are developing towards high-rate charge and discharge. Although the battery itself is covered and protected by an insulating film, there is a certain risk of damage to the film itself. Moreover, the relatively thick insulating film inevitably reduces the internal space of the battery, lowers the energy density, and a high-quality insulating film will further increase the battery cost. Therefore, for large cylindrical batteries, if the battery shell can be made non-charged, various existing problems can be well solved, and the various advantages embodied will be self-evident.

[0003] Judging from most of the currently published documents, the general way to achieve a non-charged steel shell is to separately provide a pole column with a riveting structure for the negative electrode. For example, Patent CN201608244U discloses a high-power lithium-ion power battery with a non-charged steel shell housing; it includes a positive electrode and a negative electrode. The positive electrode is welded to a positive current collector ring, and the positive current collector ring is connected to an upper cover explosion-proof component through a positive connecting aluminum strip. The positive pole column and the upper cover explosion-proof component are fixed by bolts; the negative electrode is welded to a negative current collector ring, and the negative current collector ring is directly connected to the negative pole column. An insulating gasket is provided between the negative current collector ring and the steel shell housing. The negative pole column passes through the insulating gasket and the steel shell housing, and the battery cell is a cylindrical single battery cell; there is a sealant between the negative pole column and the steel shell housing, and the negative pole column and the steel shell housing are not connected.

[0004] However, such a design makes the negative cover assembly and the positive cover assembly located at both ends of the battery respectively, and both ends occupy a large amount of height space, increasing the overall thickness of the battery. If it is assembled into a battery pack later, the relatively high height of the battery cell will result in a low space utilization rate of the battery pack, causing a reduction in the overall energy density. Summary of the Utility Model

[0005] The embodiments of the present application provide a cover assembly and a cylindrical lithium battery to at least solve the technical problem of reduced energy density caused by unreasonable structural designs such as the cover assembly of existing lithium-ion cylindrical batteries.

[0006] The first aspect embodiment of the present application provides a cover assembly, including:

[0007] A cover plate, provided with a first hole penetrating along the thickness direction of the cover plate;

[0008] A positive pole column, the positive pole column is arranged in the first hole, and the positive pole column is provided with a second hole penetrating along the thickness direction of the cover plate;

[0009] The first upper plastic part is arranged between the positive electrode column and the cover plate to insulate the cover plate from the positive electrode column;

[0010] The negative electrode column is arranged in the second hole;

[0011] The second upper plastic part is arranged between the positive electrode column and the negative electrode column to insulate them from each other.

[0012] The cover plate assembly according to the embodiment of the present application has at least the following beneficial effects:

[0013] By arranging both the positive electrode column and the negative electrode column on one side of the cover plate, compared with the scheme of arranging the positive electrode column at one end of the cylindrical lithium battery and the negative electrode column at the other end of the cylindrical lithium battery, the overall height of the cylindrical lithium battery in this scheme includes the height of the positive electrode column plus the height of the negative electrode column, while in the scheme of this embodiment, there is an overlapping part in height between the positive electrode column and the negative electrode column, and the height of the cylindrical lithium battery is the positive electrode column plus the negative electrode column minus the overlapping height of the two. Therefore, the embodiment of the present application reduces the overall height of the cylindrical lithium battery, improves the space utilization rate of the battery pack, and increases the overall energy density. At the same time, since plastic parts are arranged between the positive electrode column, the negative electrode column and the cover plate, and the plastic parts are used to insulate the three from each other, so that the negative electrode column does not need to use the battery shell as a conductor as in the prior art, that is, the outer shell of the cylindrical lithium battery in this embodiment can be made non - charged. Moreover, since the negative electrode column penetrates through the positive electrode column, compared with the scheme where the positive electrode column and the negative electrode column are separated, only one through - hole needs to be arranged on the cover plate, saving the process, and fewer through - holes on the cover plate are also beneficial to reducing the risk of liquid leakage of the cylindrical lithium battery.

[0014] In a possible implementation manner, the cover plate includes a first upper surface and a first lower surface in the thickness direction of the cover plate. A first notch is arranged on the first upper surface, and a second notch is arranged on the first lower surface. The first notch and the second notch correspond to each other in the thickness direction of the cover plate. The depth of the first notch is D1, the depth of the second notch is D2, and the thickness of the cover plate is D3, and D1 / D3 is 40% - 60%. This helps to ensure the fracture stability, that is, the valve - opening stability, of the first notch and the second notch on the basis of meeting the strength of the cover plate.

[0015] In a possible implementation, the positive electrode post has opposite first and second ends. The first end is used as the positive terminal of the cylindrical lithium battery, and the second end is used to connect to the positive current collector plate. A counterbore is provided at the second end, and a second hole is provided in the middle of the counterbore and communicates with the counterbore. The diameter of the counterbore is larger than the diameter of the second hole. The length of the positive electrode post in the non-second-hole area at the first end in the radial direction of the positive electrode post is L1, the cover plate is circular, and the radius of the cover plate is L2, and 24% ≤ L1 / L2 ≤ 30%, which ensures the overall riveting effect of the cover plate assembly, that is, ensures the strength of the positive electrode post after riveting. The length of the second end in the non-counterbore area in the radial direction of the positive electrode post is L3, and 10% ≤ L3 / L2 ≤ 15%, which ensures the overall riveting effect of the cover plate assembly, that is, ensures the strength of the positive electrode post after riveting.

[0016] In a possible implementation, the diameter of the counterbore is L4, and the diameter of the second hole is L5, and 25% ≤ L5 / L4 ≤ 30%, which helps to balance the welding strength and the welding space.

[0017] In a possible implementation, the cover plate assembly further includes a lower plastic part, which is connected to the first lower surface of the cover plate. The side surface of the second end is configured with a flush part and a protruding part. The flush part is located between the protruding part and the first lower surface of the cover plate, and the flush part, the protruding part and the first lower surface jointly define a first groove. The lower plastic part includes an embedded part and an exposed part. The embedded part is located in the first groove, and the exposed part is located outside the first groove. The length of the embedded part in the radial direction of the cover plate is L6, and the length of the exposed part in the radial direction of the cover plate is L7, and 10% ≤ L6 / L7 ≤ 30%, which helps to balance the welding strength and the welding space.

[0018] In a possible implementation, the thickness of the embedded part is L8, and the thickness of the exposed part is L9, and 30% ≤ L8 / L9 ≤ 80%, which helps to balance the inlay effect and the overall strength of the lower plastic part.

[0019] In a possible implementation, the positive electrode post includes a first inner wall surface (1211) forming the second hole, a second upper surface extending from the first inner wall surface to the first end portion, and a second lower surface located at the bottom of the counterbore and extending from the first inner wall surface to the second end portion. The negative electrode post sequentially includes a third end portion, a connecting portion, and a fourth end portion along the thickness direction of the cover plate. The connecting portion is located in the second hole. The third end portion protrudes above the second upper surface and is limited by the second upper surface. The fourth end portion protrudes above the second lower surface and is limited by the second lower surface. The second upper plastic part is disposed between the second upper surface and the third end portion, the second lower surface and the fourth end portion, and the outer peripheral surface of the connecting portion and the first inner wall surface of the second hole. The second lower surface is used to connect to the positive current collector plate, and the fourth end portion is used to connect to the negative current collector plate. The length of the third end portion in the radial direction of the cover plate is L10, the cover plate is circular, and the radius of the cover plate is L2, where 6% ≤ L10 / L2 ≤ 23%, which helps to balance the internal riveting strength and welding convenience.

[0020] In a possible implementation, the distance L11 from the fourth end portion to the first inner wall surface of the second hole in the radial direction of the negative electrode post satisfies 4 mm ≤ L11 ≤ 12 mm, which is beneficial to the assembly of the positive electrode post and the negative electrode post. The cover plate includes a first upper surface and a first lower surface along the thickness direction of the cover plate. The first upper surface is provided with a first notch, and the first lower surface is provided with a second notch. The first notch and the second notch correspond to each other along the thickness direction of the cover plate. The cover plate is circular, the first notch and the second notch are circular, and the centers of the cover plate, the first notch, and the second notch coincide. The distance from the first notch and the second notch to the edge of the cover plate is L12, where 3 mm ≤ L12 ≤ 4 mm, which is beneficial to balancing the influence of the laser sealing operation on the notch and avoiding interference with the notch of the lower plastic part.

[0021] In a possible implementation, the negative electrode post further includes a third upper surface and a third lower surface along the thickness direction of the cover plate. The third upper surface is disposed on the third end portion, and the third lower surface is disposed on the fourth end portion. The third upper surface is used as the negative terminal of the cylindrical lithium battery, and the third lower surface is used to connect to the negative current collector plate. The third lower surface is provided with an opening, and the opening forms a cavity for accommodating at least a part of the negative current collector plate. The diameter of the opening is L13, where 3 mm ≤ L13 ≤ 5 mm, which helps to increase the welding strength between the negative current collector plate and the negative electrode post. The length from the third upper surface to the second upper surface is L14, where 2 mm ≤ L14 ≤ 5 mm, which is beneficial to reducing the total height of the cylindrical lithium battery and increasing the energy density of the cylindrical lithium battery in the height direction.

[0022] The second aspect embodiment of the present application provides a cylindrical lithium battery, which includes the cover plate assembly, the outer shell, the positive current collector plate, the wound core and the negative current collector plate of the first aspect embodiment above. The positive electrode of the wound core is connected to the positive electrode column through the positive current collector plate, and the negative electrode is connected to the negative electrode column through the negative current collector plate.

[0023] The cylindrical lithium battery according to the embodiment of the present application has at least the following beneficial effects:

[0024] The cylindrical lithium battery of the embodiment of the present application reduces the total height of the cylindrical lithium battery on the basis that the outer shell is not charged, so that the space utilization rate of the battery pack is relatively high, and the overall energy density is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 is a schematic cross-sectional view of the cylindrical lithium battery provided by the embodiment of the present application;

[0027] Figure 2 is a schematic cross-sectional view of a cover plate assembly provided by the embodiment of the present application;

[0028] Figure 3 is a schematic cross-sectional view of the cover plate in a cover plate assembly provided by the embodiment of the present application;

[0029] Figure 4 is a schematic cross-sectional view of the positive electrode column in a cover plate assembly provided by the embodiment of the present application;

[0030] Figure 5 is Figure 2 an enlarged schematic view of the part A in;

[0031] Figure 6 is Figure 2 an enlarged schematic view of the part B in;

[0032] Figure 7 is Figure 2 an enlarged schematic view of the part C in;

[0033] Figure 8 is Figure 2 a schematic view of the lower plastic part hidden at the part C of;

[0034] Figure 9It is a schematic cross-sectional view of the lower plastic part in a cover plate assembly provided by an embodiment of the present application;

[0035] Figure 10 It is Figure 9 an enlarged schematic view of the D position in

[0036] Figure 11 It is a schematic cross-sectional view of the negative electrode post in a cover plate assembly provided by an embodiment of the present application.

[0037] Reference numerals:

[0038] 1 - Cover plate assembly, 11 - Cover plate, 111 - First hole, 112 - First upper surface, 113 - First lower surface, 114 - First notch, 115 - Second notch, 12 - Positive electrode post, 121 - Second hole, 1211 - First inner wall surface, 122 - First end, 1221 - Second upper surface, 123 - Second end, 1231 - Counterbore, 1232 - Second lower surface, 1233 - Flush part, 1234 - Protruding part, 124 - First groove, 13 - First upper plastic part, 14 - Negative electrode post, 141 - Third end, 142 - Connecting part, 143 - Fourth end, 144 - Third upper surface, 145 - Third lower surface, 1451 - Opening, 15 - Second upper plastic part, 16 - Lower plastic part, 161 - Embedded part, 162 - Exposed part;

[0039] 2 - Positive current collector plate;

[0040] 3 - Negative current collector plate;

[0041] 4 - Outer shell;

[0042] 5 - Winding core. Detailed implementation manners

[0043] The embodiments of the present implementation manner are described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present implementation manner, and should not be construed as a limitation to the present implementation manner.

[0044] In the description of the present implementation manner, it should be understood that for the orientation description, such as the upper, lower, front, rear, left, right, etc., the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings. It is only for the convenience of describing the present implementation manner and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present implementation manner.

[0045] In the description of this embodiment, "several" means one or more, "multiple" means more than two, and understandings such as "greater than", "less than", "exceeding", etc. do not include the corresponding number, while understandings such as "above", "below", "within", etc. include the corresponding number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features or implicitly specifying the sequence relationship of the indicated technical features.

[0046] In the description of this embodiment, unless otherwise clearly defined, terms such as "set", "installed", "connected", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in this embodiment in combination with the specific content of the technical solution.

[0047] The cover plate assembly 1 provided in the embodiment of the present application is used for assembly in a cylindrical lithium battery. Please refer to Figure 1 , Figure 2 to understand the cover plate assembly 1 of the embodiment of the present application.

[0048] As Figures 2 - 4 shown, the cover plate assembly 1 includes a cover plate 11, a positive electrode column 12, a first upper plastic part 13, a negative electrode column 14, and a second upper plastic part 15. Among them, a first hole 111 penetrating in the thickness direction of the cover plate 11 is provided on the cover plate 11, the positive electrode column 12 is arranged in the first hole 111, the positive electrode column 12 is provided with a second hole 121 penetrating in the thickness direction of the cover plate 11, and the negative electrode column 14 is arranged in the second hole 121. The first upper plastic part 13 is arranged between the positive electrode column 12 and the cover plate 11 to insulate the cover plate 11 and the positive electrode column 12, and the second upper plastic part 15 is arranged between the positive electrode column 12 and the negative electrode column 14 to insulate each other. By arranging both the positive electrode column 12 and the negative electrode column 14 on one side of the cover plate 11, compared with the scheme of arranging the positive electrode column 12 at one end of the cylindrical lithium battery and the negative electrode column 14 at the other end of the cylindrical lithium battery, the overall height of the cylindrical lithium battery in the solution of this embodiment includes the height of the positive electrode column plus the height of the negative electrode column, and there is an overlapping part in height between the positive electrode column 12 and the negative electrode column 14 in the solution of this embodiment. The height of the cylindrical lithium battery is the positive electrode column 12 plus the negative electrode column 14 minus the overlapping height of the two. Therefore, the embodiment of the present application reduces the overall height of the cylindrical lithium battery, resulting in a higher space utilization rate of the battery pack and an improved overall energy density. At the same time, since plastic parts are arranged between the positive electrode column 12, the negative electrode column 14, and the cover plate 11, and the plastic parts are used to insulate the three from each other, the negative electrode column 14 does not need to use the battery case 4 as a conductor as in the prior art, that is, the case 4 of the cylindrical lithium battery in this embodiment can be made non - charged. Furthermore, since the negative electrode column 14 penetrates through the positive electrode column 12, compared with the scheme where the positive electrode column 12 and the negative electrode column 14 are separated, only one through - hole needs to be provided on the cover plate 11, saving the process, and fewer through - holes on the cover plate 11 are also beneficial to reducing the risk of liquid leakage of the cylindrical lithium battery.

[0049] In some embodiments, the axes of the positive electrode post 12 and the negative electrode post 14 are collinear, which is beneficial to processing and assembly. In some embodiments, the axes of the positive electrode post 12 and the negative electrode post 14 pass through the center of the cover plate 11, which is beneficial to the connection between the negative electrode post 14 and the negative current collector plate 3 passing through the cylindrical lithium battery core 5.

[0050] In some embodiments, both the first hole 111 and the second hole 121 are circular holes, and the centers of the first hole 111 and the second hole 121 coincide. In some embodiments, the first upper plastic part 13 and the second upper plastic part 15 are made of insulating materials such as rubber and plastic, and the specific materials used are not limited. In some embodiments, the cover plate 11 is made of a metal material.

[0051] In some embodiments, as Figure 5 shown, the cover plate 11 includes a first upper surface 112 and a first lower surface 113 in the thickness direction of the cover plate 11. A first notch 114 is provided on the first upper surface 112, and a second notch 115 is provided on the first lower surface 113. The first notch 114 and the second notch 115 correspond to each other in the thickness direction of the cover plate 11. The depth of the first notch 114 is D1, the depth of the second notch 115 is D2, and the thickness of the cover plate 11 is D3. (D1 + D2) / D3 is 40% - 60%. The first notch 114 and the second notch 115 are explosion-proof valves, which are used to break and relieve pressure when the internal pressure of the cylindrical lithium battery is too high, so as to avoid the explosion of the cylindrical lithium battery. In this embodiment, since the first notch 114 and the second notch 115 are respectively located on the upper and lower surfaces of the cover plate 11, and the positions of the two notches correspond to each other, the depths of the two notches determine the thickness of the cover plate 11 at the notch position. If the notch is too deep, the remaining thickness of the cover plate 11 is small, reducing the strength of the cover plate 11. If the notch is too shallow, the pressure required for the first notch 114 and the second notch 115 to break is unstable, that is, the opening of the explosion-proof valve is unstable. In this embodiment, the range of (D1 + D2) / D3 is designed to be 40% - 60%, which helps to ensure the fracture stability of the first notch 114 and the second notch 115, that is, the opening stability, on the basis of meeting the strength of the cover plate 11.

[0052] In some embodiments, as Figure 3 、 Figure 4As shown, the positive electrode post 12 has opposite first and second ends 122 and 123. The first end 122 is used as the positive terminal of the cylindrical lithium battery, and the second end 123 is used to connect to the positive current collector plate 2. A counterbore 1231 is provided at the second end 123. The second hole 121 is provided in the middle of the counterbore 1231 and communicates with the counterbore 1231. The diameter of the counterbore 1231 is larger than the diameter of the second hole 121. The length of the positive electrode post 12 in the non-second-hole 121 area in the radial direction of the positive electrode post 12 at the first end 122 is L1. The cover plate 11 is circular, and the radius of the cover plate 11 is L2, and 24% ≤ L1 / L2 ≤ 30%, which ensures the overall riveting effect of the cover plate assembly 1, that is, ensures the strength of the positive electrode post 12 after riveting. Further, the preferred values of L1 / L2 are 26%, 27%, 28%, and no further limitation is made. The positive electrode post 12 and the cover plate 11 are assembled by a riveting process. Before riveting, the positive electrode post 12 has a first end 122, and then the positive electrode post 12 is passed through the cover plate 11. After using the riveting process, a second end 123 is formed, and at this time, the positive electrode post 12 and the cover plate 11 are assembled. Among them, during the assembly process, the first upper plastic part 13 needs to be placed between the positive electrode post 12 and the cover plate 11 to insulate the two after the positive electrode post 12 and the cover plate 11 are assembled.

[0053] In some embodiments, the length of the second end 123 in the non-counterbore 1231 area in the radial direction of the positive electrode post 12 is L3, and 10% ≤ L3 / L2 ≤ 15%, which ensures the overall riveting effect of the cover plate assembly 1, that is, ensures the strength of the positive electrode post 12 after riveting.

[0054] In some embodiments, the diameter of the counterbore 1231(1231) is L4, and the diameter of the second hole 121(121) is L5, and 25% ≤ L5 / L4 ≤ 30%. If the counterbore 1231 is too large, it will affect the welding space between the positive current collector plate 2 and the cover plate 11. If the counterbore 1231 is too small, it will affect the welding of the negative current collector plate 3 and the cover plate 11 and will also affect the overall riveting strength. In this embodiment, the range of L5 / L4 is designed to be 25% - 30%, which helps to balance the welding strength and the welding space.

[0055] In some embodiments, such as Figure 2 、 Figure 7As shown, the cover plate assembly 1 further includes a lower plastic part 16. The lower plastic part 16 is connected to the first lower surface 113 of the cover plate 11. The side surface of the second end portion 123 is configured with a flush portion 1233 and a protruding portion 1234. The flush portion 1233 is located between the protruding portion 1234 and the first lower surface 113 of the cover plate 11. The flush portion 1233, the protruding portion 1234 and the first lower surface 113 together define a first groove 124. The lower plastic part 16 includes an embedded portion 161 and an exposed portion 162. The embedded portion 161 is located within the first groove 124, and the exposed portion 162 is located outside the first groove 124. The length of the embedded portion 161 in the radial direction of the cover plate 11 is L6, and the length of the exposed portion 162 in the radial direction of the cover plate 11 is L7, where 10% ≤ L6 / L7 ≤ 30%. This helps to balance the welding strength and the welding space. If the embedded portion 161 is too long or too short, it will affect the welding space between the positive current collector plate 2 and the positive electrode post 12, and will also affect the overall welding strength of the cover plate assembly 1.

[0056] In some embodiments, as Figure 9 , Figure 10 shown, the thickness of the embedded portion 161 is L8, and the thickness of the exposed portion 162 is L9, where 30% ≤ L8 / L9 ≤ 80%. If the thickness of the embedded portion 161 is too thick, the embedding effect of the lower plastic part 16 is not good. If the embedded portion 161 is too thin, the overall strength of the lower plastic part 16 is not good. Designing L8 / L9 between 30% - 80% helps to balance the embedding effect and the overall strength of the lower plastic part 16.

[0057] In some embodiments, the lower plastic part 16 is connected to the first upper plastic part 13 to further enhance the insulation effect between the cover plate 11 and the positive electrode post 12.

[0058] In some embodiments, as Figure 11As shown, the positive electrode post 12 includes a first inner wall surface 1211 forming a second hole 121, a second upper surface 1221 extending from the first inner wall surface 1211 to a first end 122, and a second lower surface 1232 located at the bottom of a counterbore 1231 and extending from the first inner wall surface 1211 to a second end 123. The negative electrode post 14 sequentially includes a third end 141, a connecting portion 142, and a fourth end 143 along the thickness direction of the cover plate 11. The connecting portion 142 is located in the second hole 121. The third end 141 protrudes above the second upper surface 1221 and is limited by the second upper surface 1221. The fourth end 143 protrudes above the second lower surface 1232 and is limited by the second lower surface 1232. The second upper plastic part 15 is disposed between the second upper surface 1221 and the third end 141, between the second lower surface 1232 and the fourth end 143, and between the first inner wall surface 1211 of the second hole 121 and the outer peripheral surface of the connecting portion 142. The second lower surface 1232 is used to connect with the positive current collector plate 2, and the fourth end 143 is used to connect with the negative current collector plate 3. The fourth end 143 is used to connect with the negative current collector plate 3. The length of the third end 141 in the radial direction of the cover plate 11 is L10. The cover plate 11 is circular, and the radius of the cover plate 11 is L2, and 6% ≤ L10 / L2 ≤ 23%. If L10 is too large, the area of the cover plate 11 covered by the third end is too large, affecting the riveting strength inside the cover plate 11 and causing material waste. If L10 is too small, the area of the cover plate 11 covered by the third end is too small, which is not conducive to the internal welding dimensions and narrows the process window. Designing the range of L10 / L2 between 6% and 23% helps to balance the internal riveting strength and welding convenience. Further, the preferred values of L10 / L2 are 10%, 14%, 16%, and 20%, without further limitation.

[0059] In some embodiments, as Figure 6 shown, the distance L11 from the fourth end 143 to the first inner wall surface 1211 of the second hole 121 in the radial direction of the negative electrode post 14 is 4 mm ≤ L11 ≤ 12 mm. This is beneficial to the assembly of the positive electrode post 12 and the negative electrode post 14. If L11 is too large, the welding strength is affected. If L11 is too small, welding cannot be performed during assembly. L11 is further preferably 6 mm, 8 mm, and 10 mm, without further specific limitation. As Figure 5As shown, the cover plate 11 includes a first upper surface 112 and a first lower surface 113 in the thickness direction of the cover plate 11. A first notch 114 is provided on the first upper surface 112, and a second notch 115 is provided on the first lower surface 113. The first notch 114 and the second notch 115 correspond to each other in the thickness direction of the cover plate 11. The cover plate 11 is circular in shape, the first notch 114 and the second notch 115 are circular in shape, and the centers of the cover plate 11, the first notch 114, and the second notch 115 coincide. The distances from both the first notch 114 and the second notch 115 to the edge of the cover plate 11 are L12, and 3mm ≤ L12 ≤ 4mm. If the notch is too close to the edge of the cover plate 11, the thermal influence during laser sealing will affect the explosion-proof valve, resulting in deformation and affecting its stability. If the notch is too far from the edge of the cover plate 11, the lower plastic part 16 will interfere with the notch of the internal explosion-proof valve. Controlling the length of L12 within 3mm - 4mm is beneficial to balancing the influence of laser sealing operation on the notch and avoiding interference of the lower plastic part 16 with the notch.

[0060] In some embodiments, as Figure 11 shown, the negative electrode post 14 further includes a third upper surface 144 and a third lower surface 145 in the thickness direction of the cover plate 11. The third upper surface 144 is provided at the third end 141, and the third lower surface 145 is provided at the fourth end 143. The third upper surface 144 is used as the negative terminal of the cylindrical lithium battery, and the third lower surface 145 is used to connect with the negative current collector plate 3. An opening 1451 is provided on the third lower surface 145, and the opening 1451 forms a cavity for accommodating at least part of the negative current collector plate 3. The diameter of the opening 1451 is L13, and 3mm ≤ L13 ≤ 5mm. Designing the diameter of the opening 1451 within 3 - 5mm helps to increase the welding strength between the negative current collector plate 3 and the negative electrode post 14.

[0061] In some embodiments, as Figure 6 shown, the distance between the third upper surface 144(144) and the second upper surface 1221(1221) is L14, and 2mm ≤ L14 ≤ 5mm. If the length of L14 is less than 2mm, the riveting strength will be affected. If it is greater than 5mm, the total height of the cylindrical lithium battery will be significantly increased, which is not conducive to increasing the energy density of the cylindrical lithium battery in the height direction.

[0062] The embodiment of the present application further provides a cylindrical lithium battery, which includes the cover plate assembly 1 of the above embodiment. The cylindrical lithium battery further includes a housing 4, a positive current collector plate 2, a wound core 5, and a negative current collector plate 3. The positive electrode of the wound core 5 is connected to the positive electrode post 12 through the positive current collector plate 2, and the negative electrode is connected to the negative electrode post 14 through the negative current collector plate 3.

[0063] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this implementation. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0064] Although the embodiments of this implementation have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of this implementation, and the scope of this implementation is defined by the claims and their equivalents.

Claims

1. A cover plate assembly for a cylindrical lithium battery, characterized in that, Comprising: A cover plate (11) provided with a first hole (111) penetrating in the thickness direction of the cover plate; A positive electrode post (12) disposed in the first hole (111), the positive electrode post (12) being provided with a second hole (121) penetrating in the thickness direction of the cover plate (11); A first upper plastic part (13) disposed between the positive electrode post (12) and the cover plate (11) to insulate the cover plate (11) from the positive electrode post (12); A negative electrode post (14) disposed in the second hole (121); A second upper plastic part (15) disposed between the positive electrode post (12) and the negative electrode post (14) to insulate them from each other.

2. The cover plate assembly according to claim 1, wherein The cover plate (11) includes a first upper surface (112) and a first lower surface (113) in the thickness direction of the cover plate (11). A first notch (114) is provided on the first upper surface (112), and a second notch (115) is provided on the first lower surface (113). The first notch (114) and the second notch (115) correspond to each other in the thickness direction of the cover plate (11). The depth of the first notch (114) is D1, the depth of the second notch (115) is D2, and the thickness of the cover plate (11) is D3. (D1 + D2) / D3 is 40% - 60%.

3. The cover plate assembly according to claim 1, wherein, The positive electrode post (12) has opposite first and second ends (122, 123). The first end (122) is used as the positive terminal of the cylindrical lithium battery, and the second end (123) is used to connect to a positive current collector plate (2). A counterbore (1231) is provided in the second end (123). The second hole (121) is provided in the middle of the counterbore (1231) and communicates with the counterbore (1231). The diameter of the counterbore (1231) is larger than the diameter of the second hole (121). The length of the positive electrode post (12) in the non-second-hole (121) area in the radial direction of the positive electrode post (12) at the first end (122) is L1. The cover plate (11) is circular, and the radius of the cover plate (11) is L2. 24% ≤ L1 / L2 ≤ 30%. The length of the second end (123) in the non-counterbore (1231) area in the radial direction of the positive electrode post (12) is L3. 10% ≤ L3 / L2 ≤ 15%.

4. The cover plate assembly according to claim 3, wherein, The diameter of the counterbore (1231) is L4, and the diameter of the second hole (121) is L5. 25% ≤ L5 / L4 ≤ 30%.

5. The cover plate assembly according to claim 3, wherein The cover plate assembly further includes a lower plastic part (16), the lower plastic part (16) is connected to the first lower surface (113) of the cover plate (11), a flush part (1233) and a protruding part (1234) are formed on the side surface of the second end (123) of the positive electrode column (12), the flush part (1233) is located between the protruding part (1234) and the first lower surface (113) of the cover plate (11), and the flush part (1233), the protruding part (1234) and the first lower surface (113) jointly define a first groove (124). The lower plastic part (16) includes an embedded part (161) and an exposed part (162), the embedded part (161) is located in the first groove (124), the exposed part (162) is located outside the first groove (124), the length of the embedded part (161) in the radial direction of the cover plate (11) is L6, the length of the exposed part (162) in the radial direction of the cover plate (11) is L7, and 10% ≤ L6 / L7 ≤ 30%.

6. The cover plate assembly according to claim 5, wherein The thickness of the embedded part (161) is L8, the thickness of the exposed part (162) is L9, and 30% ≤ L8 / L9 ≤ 80%.

7. The cover plate assembly according to claim 3, wherein, The positive electrode column (12) includes a first inner wall surface (1211) forming the second hole (121), a second upper surface (1221) extending from the first inner wall surface (1211) to the first end (122), and a second lower surface (1232) located at the bottom of the counterbore (1231) and extending from the first inner wall surface (1211) to the second end (123). The negative electrode column (14) sequentially includes a third end (141), a connecting part (142), and a fourth end (143) along the thickness direction of the cover plate (11). The connecting part (142) is located in the second hole (121), the third end (141) is higher than the second upper surface (1221) and is limited by the second upper surface (1221), the fourth end (143) is higher than the second lower surface (1232) and is limited by the second lower surface (1232). The second upper plastic part (15) is disposed between the second upper surface (1221) and the third end (141), the second lower surface (1232) and the fourth end (143), and the outer peripheral surface of the first inner wall surface (1211) of the second hole (121) and the connecting part (142). The second lower surface (1232) is used to connect with the positive current collector plate (2), the fourth end (143) is used to connect with the negative current collector plate (3), the length of the third end (141) in the radial direction of the cover plate (11) is L10, the cover plate (11) is circular, and the radius of the cover plate (11) is L2, and 6% ≤ L10 / L2 ≤ 23%.

8. The cover plate assembly according to claim 7, wherein The distance L11 from the fourth end portion (143) to the first inner wall surface (1211) of the second hole (121) in the radial direction of the negative electrode post (14) satisfies 4 mm ≤ L11 ≤ 12 mm; the cover plate (11) includes a first upper surface (112) and a first lower surface (113) in the thickness direction of the cover plate (11). A first notch (114) is provided on the first upper surface (112), and a second notch (115) is provided on the first lower surface (113). The first notch (114) and the second notch (115) correspond to each other in the thickness direction of the cover plate (11). The cover plate (11) is circular in shape, the first notch (114) and the second notch (115) are circular in shape, and the centers of the cover plate (11), the first notch (114), and the second notch (115) coincide. The distances from the first notch (114) and the second notch (115) to the edge of the cover plate (11) are L12, and 3 mm ≤ L12 ≤ 4 mm.

9. The cover plate assembly according to claim 7 or 8, characterized in that, The negative electrode post (14) further includes a third upper surface (144) and a third lower surface (145) in the thickness direction of the cover plate (11). The third upper surface (144) is provided at the third end portion (141), and the third lower surface (145) is provided at the fourth end portion (143). The third upper surface (144) is used as the negative terminal of the cylindrical lithium battery, and the third lower surface (145) is used to connect to the negative electrode current collector plate (3). An opening (1451) is provided on the third lower surface (145), and the opening (1451) forms a cavity for accommodating at least a part of the negative electrode current collector plate (3). The diameter of the opening (1451) is L13, and 3 mm ≤ L13 ≤ 5 mm; the length from the third upper surface (144) to the second upper surface (1221) is L14, and 2 mm ≤ L14 ≤ 5 mm.

10. A cylindrical lithium battery, characterized in that, Comprising the cover plate assembly (1), the outer shell (4), the positive electrode current collector plate (2), the wound core (5), and the negative electrode current collector plate (3) according to any one of claims 1-9, the positive electrode of the wound core (5) is connected to the positive electrode post (12) through the positive electrode current collector plate (2), and the negative electrode of the wound core (5) is connected to the negative electrode post (14) through the negative electrode current collector plate (3).

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