Cover plate assembly and battery

Abstract

The present application relates to the technical field of batteries, and discloses a cover plate assembly and a battery. The cover plate assembly comprises a cover plate, poles, sealing rings, and welding rings. The outer contour of a first pole section of each pole is larger than that of a second pole section thereof; the first pole section is limited on a first side of the cover plate; and the welding rings are arranged on a second side of the cover plate and are welded on the corresponding second pole sections. The cover plate assembly can be assembled simply by welding the welding rings on the second pole sections, so that the assembly process is simple. The value range of the welding penetration depth A of a welding seam is limited to be 1.2 PM / D≤A≤0.8 T, and the welding penetration depth is associated with the full-life-cycle pressure P of the sealing ring, the ratio M of the contact area of the sealing ring and the welding ring to the perimeter of the inner ring of the welding ring, the shearing strength D of the welding seam, and the thickness T of the welding ring, so that sufficient welding strength can be ensured, and the sealing rings can be prevented from being melted, ensuring airtightness, controlling product quality by controlling the welding penetration depth.

Description

Cover plate assembly and battery

[0001] Related Art Cross Reference

[0002] The present application claims priority to the Chinese patent application No. 202411238714.6, filed on September 5, 2024, and entitled "Cover plate assembly and battery", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of batteries, in particular to a cover plate assembly and a battery. BACKGROUND

[0004] A battery mainly consists of a shell, a pole group placed in the shell, a cover plate assembly closing the open end of the shell, and the like. A traditional cover plate assembly is usually a riveted cover plate, which includes a cover plate, a pole, a riveting block, a plastic part, a sealing ring, and the like. The pole is arranged in a mounting hole on the cover plate, the plastic part and the sealing ring are located between the pole and the cover plate, and play a sealing and insulating role. The pole is riveted to the cover plate through the riveting block. The riveting process of the riveted cover plate has a complex assembly procedure, is difficult to operate, and the product quality is difficult to control. SUMMARY

[0005] Therefore, the present application provides a cover plate assembly and a battery to solve the problems of complex assembly procedure, difficult operation, and difficult control of product quality of the cover plate assembly.

[0006] In a first aspect, the present application provides a cover plate assembly, comprising: a cover plate, having a first through hole; a pole, comprising a first column segment and a second column segment fixedly connected, an outer contour of the first column segment being larger than an outer contour of the second column segment, the second column segment being arranged in the first through hole, and the first column segment being located on one side of the cover plate; a sealing ring, sleeved on the second column segment, and located on a side of the cover plate away from the first column segment; and a welding ring, sleeved on the second column segment, located on a side of the sealing ring away from the cover plate, and abutting against the sealing ring, at least part of an inner wall of the welding ring being welded with part of an outer circumferential surface of the second column segment to form a welding seam, an axial welding penetration depth A of the welding seam along the pole satisfying the formula: 1.2PM / D≤A≤0.8T; wherein P is a full life cycle pressure of the sealing ring, M is a ratio of a contact area of the sealing ring and the welding ring to a circumference of an inner ring of the welding ring, D is a shear strength of the welding seam, and T is a dimension of the welding ring along a central line extension direction thereof.

[0007] Beneficial effects: By setting the outer contour of the first column segment of the pole column to be larger than the outer contour of the second column segment, the second column segment passes through the first through hole on the cover plate, the first column segment is limited on the first side of the cover plate, by setting the welding ring on the second side of the cover plate and welding the welding ring on the second column segment, the limitation of the pole column from the second side of the cover plate is realized, so as to realize the limitation of the pole column along its axial direction, during the assembly process of the cover plate assembly, only the welding of the welding ring on the second column segment is needed to realize the installation of the pole column on the cover plate, prevent the pole column from being separated from the cover plate, the assembly process is simple, the operation difficulty is smaller, and the sealing ring is compressed by the welding ring, the sealing property between the pole column and the cover plate and the insulation between the welding ring and the cover plate are guaranteed, the safety of the battery is improved, at the same time, by limiting the welding penetration A of the welding seam between the welding ring and the second column segment to be 1.2PM / D≤A≤0.8T, the welding penetration is related to the full life cycle pressure P of the sealing ring, the ratio M of the contact area of the sealing ring and the welding ring to the circumference of the inner ring of the welding ring, the shear strength D of the welding seam and the thickness T of the welding ring, the control of the welding penetration size is realized, which can not only ensure that the welding has sufficient welding strength and guarantee the compression effect of the welding ring on the sealing ring, but also can avoid that the heat generated by welding melts the sealing ring, so as to guarantee the air tightness and improve the safety performance of the battery, so as to realize the accurate control of the product quality by controlling the size of the welding penetration.

[0008] In an optional embodiment, the full life cycle pressure P of the sealing ring is 1.3MPa≤P≤30MPa; and / or, the ratio M of the contact area of the sealing ring and the welding ring to the circumference of the inner ring of the welding ring is 0.6mm≤M≤3mm; and / or, the shear strength D of the welding seam is 50MPa≤D≤2000MPa; and / or, the size T of the welding ring in the direction of the center line thereof is 0.8mm≤T≤5mm.

[0009] Beneficial effects: By setting the full life cycle pressure P of the sealing ring in the range of 1.3MPa to 30MPa, the pressure borne by the sealing ring is ensured to be within a reasonable range, so that the compression amount of the sealing ring is kept within a reasonable range, which can not only ensure that the sealing ring can provide sufficient sealing performance to ensure the air tightness of the battery, but also can avoid the sealing ring bearing excessive pressure to reduce the reliability, thereby improving the safety of the battery. By setting the ratio M of the contact area of the sealing ring and the welding ring to the circumference of the inner ring of the welding ring in the range of 0.6mm to 3mm, the air tightness of the cover plate assembly can be ensured to prevent air leakage between the pole and the cover plate, improve the safety of the battery, and avoid excessive cost. By setting the shear strength of the weld in the range of 50MPa-2000MPa, the weld can not only have sufficient strength, but also maintain reasonable cost. By setting the thickness T of the welding ring in the range of 0.8mm-5mm, the welding ring can not only have sufficient thickness to avoid deformation after welding with the pole, thereby ensuring the quality of the battery, but also avoid excessive thickness of the welding ring to avoid excessive weight, thereby saving cost and improving the volume energy density of the battery.

[0010] In an alternative embodiment, an end of the second column segment away from the first column segment is configured with a groove, the groove is recessed from a part of the end face of the second column segment towards the direction close to the first column segment, and the groove is adapted to provide accommodation space for the tab on the pole group.

[0011] Beneficial effects: By configuring the groove on the end face of the second column segment to accommodate the tab on the pole group, the overall height of the pole and the pole group after welding can be reduced, thereby improving the volume utilization rate of the battery.

[0012] In an alternative embodiment, the thickness of the side wall of the groove is K, wherein the value range of K is: 0.8mm≤K≤3mm.

[0013] Beneficial effects: The welding of the second column segment and the welding ring can be ensured to realize the fixed connection of the welding ring and the pole, and the weight of the pole can be avoided to be too large, thereby reducing the cost as much as possible and ensuring the forming effect of the pole.

[0014] In an alternative embodiment, the surface of the side of the welding ring away from the first column segment is flush with the end face of the second column segment away from the first column segment, and the weld extends from the end face of the second column segment away from the first column segment towards the direction close to the first column segment.

[0015] Beneficial effects: by setting the surface of the welding ring away from the side of the first column segment to be flush with the end face of the second column segment away from the first column segment, the flatness of the surface is better, on the one hand, it is convenient to ensure the consistency of assembly, improve the product quality, on the other hand, the flush surface faces the pole group in the battery shell, which can reduce the damage to the pole group and further improve the quality of the battery; And convenient for welding operation between welding ring and pole, it is beneficial to improve the welding quality.

[0016] In an optional embodiment, the projection of the welding seam on the plane where the end face of the second column segment away from the first column segment is V, wherein the value range of V is: 0.5mm≤V≤0.9K.

[0017] Beneficial effects: it can not only ensure that the welding seam has enough strength to avoid breaking during use, but also avoid welding through the side wall of the groove, avoid melting the lower plastic part and the sealing ring, thereby further improving the welding quality, improving the reliability of welding, ensuring the safety performance of the battery, and at the same time, reducing energy consumption and cost as much as possible.

[0018] In an optional embodiment, the cover plate assembly further comprises: a lower plastic part, the lower plastic part is arranged on the side of the cover plate away from the first column segment, a second through hole is formed in the lower plastic part, the second column segment passes through the second through hole, the contour size of the second through hole is smaller than the size of the outer ring of the welding ring and larger than the size of the inner ring of the welding ring, a lap joint part is formed on the edge of the body of the lower plastic part close to the second through hole, the lap joint part is located between the welding ring and the cover plate, the lap joint part is lapped with the outer ring edge of the welding ring and located on the side of the welding ring facing the cover plate, the lap joint part forms a ring, and the ring width of the ring formed by the lap joint part is W, wherein the value range of W is: 0.8mm-5mm.

[0019] Beneficial effects: it can not only ensure the stability of the assembly of the lower plastic part and the welding ring and ensure the insulation between the welding ring and the cover plate, but also avoid the excessive weight caused by the excessive size of the welding ring, thereby reducing the cost.

[0020] In an optional embodiment, a recess is arranged on the cover plate, the recess is recessed from the part area on the surface of the cover plate away from the first column segment towards the direction close to the first column segment, the first through hole is arranged in the recess, the cross section of the lap joint part is "L" type, the lap joint part is located in the recess, and the welding ring is located in the space formed between the first side and the second side of the lap joint part.

[0021] Beneficial effects: the recess provides space for installation of the lap joint and the welding ring, the lap joint in the "L" shape is convenient to set in the recess, the welding ring is located in the space formed between the first side and the second side of the lap joint in the "L" shape, so that the lower surface of the welding ring is flush with the lower surface of the lower plastic part, thereby maintaining flatness and preventing damage to the polar group.

[0022] In a second aspect, the application further provides a battery, comprising: a shell having an open end; a polar group arranged in the shell; and the cover plate assembly described above, which is arranged at the open end of the shell to close the shell.

[0023] In an alternative embodiment, the polar post comprises a positive polar post and a negative polar post; the number of the polar group is one, the positive tab of the polar group is welded to the positive polar post, and the negative tab of the polar group is welded to the negative polar post; or the number of the polar group is multiple, the positive tabs of the multiple polar groups are welded to the positive polar post, and the negative tabs of the multiple polar groups are welded to the negative polar post.

[0024] Because the battery comprises the cover plate assembly, which has the same effects as the cover plate assembly, no further description is given here. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0026] Fig. 1 is an exploded view of a cover plate assembly according to an embodiment of the present application;

[0027] Fig. 2 is a top view of the cover plate assembly shown in Fig. 1 after assembly;

[0028] Fig. 3 is a sectional view in the direction of F-F in Fig. 2;

[0029] Fig. 4 is a partial enlarged view of B in Fig. 3;

[0030] Fig. 5 is a partial enlarged view of C in Fig. 4;

[0031] Fig. 6 is a partial enlarged view of D in Fig. 4;

[0032] Fig. 7 is a partial structure view of a cover plate according to an embodiment of the present application;

[0033] Fig. 8 is a structure view of a polar post according to an embodiment of the present application;

[0034] Fig. 9 is a structural schematic diagram of the bottom view of the pole post shown in Fig. 8;

[0035] Fig. 10 is a sectional view of the pole post shown in Fig. 8;

[0036] Fig. 11 is a structural schematic diagram of another pole post according to an embodiment of the present application;

[0037] Fig. 12 is a structural schematic diagram of the bottom view of the pole post shown in Fig. 11;

[0038] Fig. 13 is a structural schematic diagram of the assembly of the cover plate assembly and one pole group according to an embodiment of the present application;

[0039] Fig. 14 is a partial enlarged schematic diagram of E in Fig. 13;

[0040] Fig. 15 is a structural schematic diagram of the assembly of the cover plate assembly and two pole groups according to an embodiment of the present application.

[0041] Legend: 1, cover plate; 101, first through hole; 102, recessed part; 103, explosion-proof through hole; 2, pole post; 201, first post segment; 202, second post segment; 203, groove; 3, sealing ring; 4, welding ring; 5, lower plastic part; 501, second through hole; 502, overlapping part; 503, support part; 504, third through hole; 6, upper plastic part; 7, pole group; 8, explosion-proof valve; 801, explosion-proof valve protection film; 901, first welding mark; 902, second welding mark; 10, welding seam. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0043] The embodiments of the present application will be described below in combination with Figs. 1 to 15.

[0044] According to the embodiments of the present application, in one aspect, a cover plate assembly is provided, as shown in FIGS. 1-12, which comprises a cover plate 1, a pole 2, a sealing ring 3 and a welding ring 4. The cover plate 1 is provided with a first through hole 101; the pole 2 comprises a first column segment 201 and a second column segment 202 fixedly connected, the outer contour of the first column segment 201 is larger than that of the second column segment 202, the second column segment 202 is arranged in the first through hole 101, and the first column segment 201 is located on one side of the cover plate 1; the sealing ring 3 is sleeved on the second column segment 202, and the sealing ring 3 is located on the side of the cover plate 1 away from the first column segment 201; the welding ring 4 is sleeved on the second column segment 202, the welding ring 4 is located on the side of the sealing ring 3 away from the cover plate 1 and abuts against the sealing ring 3, at least part of the area on the inner wall of the welding ring 4 is welded with part of the area on the outer circumferential surface of the second column segment 202 to form a weld 10, the axial welding penetration depth A of the weld 10 along the pole 2 satisfies the formula: 1.2PM / D≤A≤0.8T; wherein P is the service life pressure of the sealing ring 3, M is the ratio of the contact area of the sealing ring 3 and the welding ring 4 to the inner ring circumference of the welding ring 4, D is the shear strength of the weld 10, and T is the size of the welding ring 4 in the direction along the center line thereof. The size of the outer contour of the first column segment 201 is larger than that of the second column segment 202; the outer contour of the first column segment 201 refers to the outer contour line of the shape of the first column segment 201 in the cross section perpendicular to the axial direction of the pole 2; the outer contour of the second column segment 202 refers to the outer contour line of the shape of the second column segment 202 in the cross section perpendicular to the axial direction of the pole 2; the size T of the welding ring 4 in the direction along the center line thereof is the thickness of the welding ring 4, and the center line of the welding ring 4 coincides with the axis of the pole 2.

[0045] The cover plate assembly of the embodiment is used to limit the pole post 2 from the second side of the cover plate 1 by setting the outer contour of the first column segment 201 of the pole post 2 to be larger than the outer contour of the second column segment 202, the second column segment 202 passes through the first through hole 101 on the cover plate 1, the first column segment 201 is limited on the first side of the cover plate 1, the welding ring 4 is arranged on the second side of the cover plate 1 and welded on the second column segment 202, the limitation of the pole post 2 from the second side of the cover plate 1 is realized, thereby realizing the limitation of the pole post 2 along the axial direction thereof, in the assembly process of the cover plate assembly, the welding ring 4 is welded on the second column segment 202, the pole post 2 is installed on the cover plate 1, the pole post 2 is prevented from being separated from the cover plate 1, the assembly process is simple, the operation difficulty is small, the sealing ring 3 is compressed by the welding ring 4, the sealing property between the pole post 2 and the cover plate 1 and the insulation between the welding ring 4 and the cover plate 1 are ensured, the safety of the battery is improved, meanwhile, the welding depth A of the welding seam 10 between the welding ring 4 and the second column segment 202 is limited to 1.2PM / D≤A≤0.8T, the welding depth is related to the full life cycle pressure P of the sealing ring 3, the ratio M of the contact area of the sealing ring 3 and the welding ring 4 to the circumference of the inner ring of the welding ring 4, the shear strength D of the welding seam 10 and the thickness T of the welding ring 4, the welding depth is controlled, the welding strength is ensured, the compression of the sealing ring 3 by the welding ring 4 is ensured, the heat generated by welding is prevented from melting the sealing ring 3, the air tightness is ensured, the safety of the battery is improved, thereby realizing the accurate control of the product quality by controlling the welding depth.

[0046] It should be noted that the first through hole 101 is slightly larger than the outer contour of the second column segment 202, which can allow the second column segment 202 to pass through; the first through hole 101 is smaller than the outer contour of the first column segment 201, and the first column segment 201 cannot pass through the first through hole 101 and is limited on the first side of the cover plate 1.

[0047] It should be noted that the weld is a joint formed by melting the metal at the joint with the high temperature of the welding heat source. In combination with FIGS. 4 and 5, the weld 10 extends from the end face of the second column segment 202 away from the first column segment 201 to the direction close to the first column segment 201, and is in an inverted conical shape. The weld 10 is located between the second column segment 202 and the welding ring 4, and connects the second column segment 202 and the welding ring 4. The welding penetration refers to the distance between the deepest part of the melted part of the base material and the surface of the base material. The size of the penetration is related to the laser power, focal length, welding speed and other factors. If the welding penetration is too small, the welding strength is difficult to meet the requirements, and the compression effect of the welding ring 4 on the sealing ring 3 is weakened, which leads to insufficient airtightness and affects the safety performance of the battery. If the welding penetration is too large, a hard molten pool is formed, which is easy to produce welding defects such as hot cracks and pores, thereby seriously affecting the welding quality. In addition, too much heat generated by welding or welding through the welding ring 4 along the thickness direction of the welding ring 4 can melt the sealing ring, which affects the airtightness and thus affects the safety of the battery.

[0048] In one embodiment, the value range of the full life cycle pressure P of the sealing ring 3 is 1.3 MPa≤P≤30 MPa. The full life cycle refers to a design theory that all relevant factors are comprehensively planned and optimized in the product design stages considering all links in the product life cycle. In order to ensure the airtightness of the battery, the sealing ring 3 is compressed under pressure, and the pressure borne by the sealing ring 3 is the full life cycle pressure P of the sealing ring 3. If the full life cycle pressure P of the sealing ring 3 is less than 1.3 MPa, P is too small, and the compression amount of the sealing ring 3 is small, which leads to insufficient airtightness. If the full life cycle pressure P of the sealing ring 3 is greater than 30 MPa, P is too large, and the sealing ring 3 bears too much pressure, which reduces the reliability and is easy to be damaged. Therefore, by setting the value of the full life cycle pressure P of the sealing ring 3 in the range of 1.3 MPa to 30 MPa, the pressure borne by the sealing ring 3 is kept within a reasonable range, and the compression amount of the sealing ring 3 is kept within a reasonable range. The sealing ring 3 can provide sufficient airtightness to ensure the airtightness of the battery, and can avoid the sealing ring 3 bearing too much pressure to reduce the reliability, thereby improving the safety of the battery.

[0049] In one embodiment, the ratio M of the contact area between the sealing ring 3 and the welding ring 4 to the circumference of the inner ring of the welding ring 4 is 0.6 mm≤M≤3 mm. It should be noted that the contact area between the sealing ring 3 and the welding ring 4 is S, and the circumference of the inner ring of the welding ring 4 is C, so M=S / C, wherein the unit of the contact area S between the sealing ring 3 and the welding ring 4 is mm 2, the ratio M is in mm, the sealing ring 3 is in contact with the side of the welding ring 4 facing the first column segment 201, and the contact surface is annular. As can be seen from FIGS. 5-6, the annular ring width of the contact surface is the ring width of the sealing ring 3. It can be seen that the greater the value of M, the greater the annular ring width of the contact surface, the greater the ring width of the sealing ring 3, the greater the sealing area, and the better the sealing performance. If M is less than 0.6 mm, the annular ring width of the contact surface is too small, the sealing area is too small, the air tightness is poor, and the battery is prone to air leakage between the pole column 2 and the cover plate 1, which is poor in safety. If M is greater than 3 mm, the annular ring width of the contact surface is too large, the size of the sealing ring 3 is too large, and the cost is high. Therefore, by setting the ratio M of the contact area of the sealing ring 3 and the welding ring 4 to the inner ring circumference of the welding ring 4 to be within the range of 0.6 mm to 3 mm, the air tightness of the cover plate assembly can be ensured, air leakage between the pole column 2 and the cover plate 1 can be prevented, the safety of the battery can be improved, and high cost can be avoided.

[0050] In one embodiment, the shear strength D of the weld 10 is within the range of 50 MPa≤D≤2000 MPa. It should be noted that the shear strength refers to the maximum shear stress that a material can withstand when subjected to shear force, and is an index of the shear resistance of the material when subjected to external shear force. The shear strength of the weld 10 can be considered as the minimum value of the shear strength of the pole column 2 and the shear strength of the welding ring 4. If the shear strength D of the weld 10 is less than 50 MPa, the weld strength is small, and the weld 10 is prone to cracking when subjected to shear force, which affects the quality of the battery. If the shear strength D of the weld 10 is greater than 2000 MPa, the cost of the required material is high, and it is not very meaningful. Therefore, by setting the shear strength of the weld 10 within the range of 50 MPa-2000 MPa, the weld 10 can have sufficient strength and reasonable cost.

[0051] In one embodiment, the dimension T of the welding ring 4 along the direction of the center line of the welding ring 4 is in the range of 0.8mm≤T≤5mm. It should be noted that the dimension of the welding ring 4 along the direction of the center line of the welding ring 4 is the thickness of the welding ring 4, i.e. the dimension along the "up-down" direction indicated by the arrow in FIG. 5. If the thickness of the welding ring 4 is less than 0.8mm, the welding ring 4 is too thin, and after the welding ring 4 is assembled and welded with the pole 2, the welding ring 4 will be deformed, which affects the quality of the battery. If the thickness of the welding ring 4 is greater than 5mm, the welding ring 4 is too thick, the weight is too large, the cost is increased, and it is not conducive to the improvement of the volume energy density of the battery. Therefore, by setting the thickness T of the welding ring 4 in the range of 0.8mm-5mm, the welding ring 4 can have sufficient thickness to avoid deformation after the welding ring 4 is welded with the pole 2, thereby ensuring the quality of the battery, and can also avoid the welding ring 4 being too thick to avoid the weight being too large, thereby saving costs and being conducive to improving the volume energy density of the battery.

[0052] In one embodiment, the second pole segment 202 is configured with a groove 203 at one end away from the first pole segment 201. The groove 203 is recessed from the part of the end face of the second pole segment 202 towards the first pole segment 201, and the groove 203 is adapted to provide accommodation space for the tab on the pole group 7. It should be noted that the groove 203 is recessed from the part of the end face of the second pole segment 202 away from the first pole segment 201 towards the first pole segment 201, and the end of the second pole segment 202 where the groove 203 is provided faces the inside of the battery case. The tab on the pole group 7 in the inside of the battery case extends into the groove 203 to be electrically connected with the pole 2. In the traditional pole, the flat surface is directly connected with the tab, while in the present embodiment, the groove 203 is configured on the end face of the second pole segment 202 to accommodate the tab on the pole group 7, which can reduce the overall height of the pole 2 after being welded with the pole group 7, thereby improving the volume utilization of the battery.

[0053] It should be noted that the cross section of the second pole segment 202 is a closed geometric shape or a ring shape, and the outer contour of the second pole segment 202 refers to the contour line on the side of the cross section of the second pole segment 202 away from the center line of the pole 2. The cross section of the first pole segment 201 is a closed geometric shape, and the outer contour of the first pole segment 201 is the contour line of the closed geometric shape, which can be circular or rectangular or racetrack-shaped or other polygonal shapes. The cross section refers to the cross section of the pole parallel to the large face of the cover plate.

[0054] The pole 2 can be composed of a single material, such as a pure copper pole or a pure aluminum pole. The pole 2 can also be composed of multiple materials, such as a copper-aluminum composite pole.

[0055] In an embodiment, the thickness of the side wall of the groove 203 is K, where 0.8mm≤K≤3mm. In combination with FIG. 6, the thickness of the side wall of the groove 203 refers to the size of the solid part of the second pole segment 202 corresponding to the groove 203 in the direction perpendicular to the pole center line, i.e. in the "left-right" direction indicated by the arrow in FIG. 3 and FIG. 6. If the thickness of the side wall of the groove 203 is less than 0.8mm, the thickness of the solid part of the second pole segment 202 corresponding to the groove 203 is too small, which will be melted when welded with the welding ring 4, and cannot be welded with the welding ring 4. If the thickness of the side wall of the groove 203 is greater than 3mm, the thickness of the solid part of the second pole segment 202 corresponding to the groove 203 is too large, which causes the weight of the pole to be too large, the cost is high, and the stamping forming effect is not good. Therefore, by limiting the thickness K of the side wall of the groove 203 to be in the range of 0.8mm to 3mm, the welding of the second pole segment 202 and the welding ring 4 can be ensured, the fixed connection of the welding ring 4 and the pole 2 can be realized, the weight of the pole 2 can be avoided to be too large, so as to reduce the cost as much as possible, and the forming effect of the pole can be ensured.

[0056] In an embodiment, the surface of the side of the welding ring 4 away from the first pole segment 201 is flush with the end face of the second pole segment 202 away from the first pole segment 201, and the welding seam 10 extends from the end face of the second pole segment 202 away from the first pole segment 201 to the direction close to the first pole segment 201. By setting the surface of the side of the welding ring 4 away from the first pole segment 201 to be flush with the end face of the second pole segment 202 away from the first pole segment 201, the flatness of the surface is good, which on the one hand facilitates to ensure the consistency of assembly, improves the product quality, and on the other hand, the flush surface of the welding ring 4 faces the pole group 7 inside the battery shell, which can reduce the damage to the pole group 7, further improves the quality of the battery, and facilitates the welding operation between the welding ring 4 and the pole 2, which is conducive to improving the welding quality.

[0057] In one embodiment, the width of the projection of the weld 10 on the plane of the end face of the second column segment 202 away from the first column segment 201 is V, wherein V is in the range of 0.5mm≤V≤0.9K. The width V of the projection of the weld 10 on the plane of the end face of the second column segment 202 away from the first column segment 201 is the fusion width of the weld 10, which refers to the width perpendicular to the extension direction of the welding track of the weld 10, i.e. the dimension of the weld 10 in the "left-right" direction indicated by the arrow in FIG. 3 and FIG. 5. Specifically, the weld 10 is located between the inner wall of the welding ring 4 and the outer circumferential surface of the second column segment 202, the welding track extends along the outer contour on the end face of the second column segment 202, and the weld 10 is annular or a part of an annulus. Therefore, the fusion width of the weld 10 is the width of the annulus in which the weld 10 is located. The size of the fusion width of the weld 10 can be controlled by adjusting the laser power and other parameters. If the fusion width of the weld 10 is less than 0.5mm, the size of the weld fusion width is too small, the weld fusion width is too narrow, the weld strength is insufficient, and the weld is prone to breakage during use. If the effective fusion width is greater than 0.9K, the size of the weld fusion width is too large, which can cause the weld to penetrate the side wall of the groove 203, affecting the connection quality of the welding ring 4 and the pole 2, and also easily causing the lower plastic part 5 and the sealing ring 3 to melt, reducing the reliability. In addition, the required welding power is high, the energy consumption of the equipment increases, and the cost increases. Therefore, by setting the weld fusion width of the weld 10 in the range of 0.5mm-0.9K, the weld can have sufficient strength to avoid breaking during use, and the weld can also avoid penetrating the side wall of the groove 203 and melting the lower plastic part 5 and the sealing ring 3, thereby further improving the welding quality, improving the reliability of the welding, ensuring the safety performance of the battery, and at the same time reducing the energy consumption and cost as much as possible.

[0058] In one embodiment, the cover plate assembly further comprises: a lower plastic part 5 arranged on the side of the cover plate 1 away from the first column segment 201, the lower plastic part 5 is provided with a second through hole 501, a second column segment is arranged in the second through hole, the contour size of the second through hole is smaller than the size of the outer ring of the welding ring and larger than the size of the inner ring of the welding ring, a lap joint portion 502 is formed on the edge of the body of the lower plastic part 5 close to the second through hole 501, the lap joint portion 502 is located between the welding ring 4 and the cover plate 1, the lap joint portion 502 is lapped with the outer ring edge of the welding ring 4 and the lap joint portion 502 is located on the side of the welding ring 4 facing the cover plate, the lap joint portion forms a ring shape, and the ring width of the ring shape formed by the lap joint portion is W, wherein the value range of W is 0.8mm-5mm. It should be noted that the welding ring 4 is annular, the portion lapped by the lap joint portion 502 and the welding ring 4 forms a ring shape, which is located on the surface of the welding ring 4 on the side facing the cover plate 1, and the outer ring of the ring shape coincides with the outer ring of the welding ring 4, and the inner ring of the ring shape is located between the outer ring and the inner ring of the welding ring 4. The lower plastic part 5 is located on the second side of the cover plate 1, the second column segment 202 on the pole 2 passes through the second through hole 501 on the lower plastic part 5, and the welding ring 4 is located on the side of the lower plastic part 5 away from the cover plate 1. By lapping the lap joint portion 502 formed on the edge of the body of the lower plastic part 5 close to the second through hole 501 with the outer ring edge of the welding ring 4, that is, in the direction perpendicular to the plane of the cover plate 1, the side of the lap joint portion 502 away from the cover plate 1 is lapped with the side of the welding ring 4 facing the cover plate 1, the lower plastic part 5 separates the cover plate 1 and the welding ring 4, thereby realizing the insulation between the welding ring 4 and the cover plate 1, and the welding ring 4 presses the lower plastic part 5 on the cover plate 1. If the ring width W of the ring shape formed by the lap joint portion is less than 0.8mm, the size of the lap joint portion is too small, the lower plastic part 5 is unstable after being assembled with the welding ring 4, the lower plastic part 5 is easy to fall off, and there is a risk of insulation failure between the cover plate 1 and the welding ring 4. If the ring width W of the ring shape formed by the lap joint portion is greater than 5mm, the size of the lap joint portion is too large, the ring width of the welding ring 4 needs to be increased, which increases the weight and cost, and is not recommended for use. Therefore, by setting the ring width W of the ring shape formed by the lap joint portion in the range of 0.8mm to 5mm, the stability of the assembly of the lower plastic part 5 and the welding ring 4 can be ensured, the insulation between the welding ring 4 and the cover plate 1 can be ensured, and the excessive size of the welding ring 4 can be avoided to reduce the cost.

[0059] In one embodiment, the cover plate 1 is provided with a recess 102, the recess 102 is recessed from a part of the surface of the first side of the cover plate 1 away from the first column segment 201 to the direction close to the first column segment 201, the first through hole 101 is arranged in the recess 102, the cross section of the lap joint part 502 is in the shape of "L", the lap joint part 502 is arranged in the recess 102, and the welding ring 4 is arranged in the space left between the first side and the second side of the lap joint part 502. Further, as shown in FIG. 6, the recess 102 is recessed from a part of the surface of the second side of the cover plate 1 to the direction close to the first side of the cover plate 1; in the cross section through the center line of the first through hole 101 (i.e. in the plane of the axial cross section of the pole column 2), the cross section of the lap joint part 502 is in the shape of inverted "L"; the recess 102 provides a space for the installation of the lap joint part 502 and the welding ring 4, the lap joint part 502 in the shape of "L" is arranged in the recess 102, the welding ring 4 is arranged in the space left between the first side and the second side of the lap joint part 502 in the shape of "L", so that the lower surface of the welding ring 4 is flush with the lower surface of the lower plastic part 5, thereby maintaining the flatness and preventing damage to the pole group. Wherein, the lower surface of the lower plastic part 5 refers to the lower surface of the main body part of the lower plastic part 5, the lower surface refers to the surface in the direction of "down" indicated by the arrow in FIG. 6; the total thickness of the cover plate 1, the lower plastic part 5 and the welding ring 4 refers to the dimension in the direction of "up and down" indicated by the arrow in FIG. 6. The lower surface of the main body part of the lower plastic part 5 is in contact with the lower surface of the part of the cover plate 1 except the recess 102.

[0060] Optionally, the end of the second column segment 202 away from the first column segment 201, the side of the welding ring 4 away from the first column segment 201 and the side of the main body part of the lower plastic part 5 away from the cover plate 1 are flush.

[0061] In one embodiment, the lower plastic part 5 is provided with a support part 503, the support part 503 protrudes from the lower surface of the main body part of the lower plastic part 5, and the support part 503 is configured as a groove open to the cover plate 1, a third through hole 504 is arranged on the bottom surface of the groove to prevent the accumulation of electrolyte in the groove and affect the performance of the battery. Optionally, the number of third through holes 504 is multiple.

[0062] In one embodiment, the cover plate assembly further comprises an upper plastic part 6, the upper plastic part 6 is arranged between the pole column and the cover plate assembly, the upper plastic part 6 is in the shape of bending and comprises a first bending part, a second bending part and a third bending part connected in sequence, wherein the second bending part is pressed between the first side of the cover plate 1 and the side of the first column segment 201 close to the cover plate 1, the first bending part is wrapped on the outer peripheral surface of the first column segment 201, and the third bending part is inserted into the first through hole 101 and pressed between the second column segment 202 and the inner wall of the first through hole 101, so as to ensure the insulation between the pole column 2 and the cover plate 1.

[0063] In one embodiment, the cover plate is further provided with an explosion-proof through hole 103, and the cover plate assembly further comprises an explosion-proof valve 8 installed in the explosion-proof through hole 103. The explosion-proof valve 8 is opened when the internal pressure of the battery is too high, so as to discharge the high-pressure gas in the battery and prevent the battery from exploding, thereby improving the safety of the battery. The explosion-proof valve 8 is provided with an explosion-proof valve protection film 801 to provide protection for the explosion-proof valve 8 when the explosion-proof valve 8 is not opened.

[0064] The assembly sequence of the cover plate assembly of the embodiment is as follows:

[0065] First, the cover plate 1 is welded with the explosion-proof valve 8, and the explosion-proof valve protection film 801 is attached to the surface of the explosion-proof valve 8. Then, the pole post 2, the upper plastic part 6, the lower plastic part 5, the sealing ring 3 and the welding ring 4 are assembled to the cover plate. Finally, the welding ring 4 is welded with the pole post 2. The assembly process is simple, convenient to operate, has high production efficiency and low cost.

[0066] According to the embodiment of the present application, on the other hand, a battery is also provided, comprising: a shell, a pole group 7 and the above-mentioned cover plate assembly. The shell has an open end; the pole group 7 is arranged in the shell; and the cover plate assembly is arranged at the open end of the shell to close the shell. The battery comprises the cover plate assembly, has the same effect as the cover plate assembly, and will not be described here.

[0067] In one embodiment, the cover plate 1 in the cover plate assembly is provided with two first through holes 101, the number of the pole posts 2 is two and corresponds to the two first through holes 101 one by one, and the pole posts 2 include one positive pole post and one negative pole post. As shown in FIGS. 13 and 14, the number of the pole groups 7 is one, the positive lug of the pole group 7 is welded with the positive pole post, and the negative lug of the pole group 7 is welded with the negative pole post. Specifically, first, the lugs on the pole group 7 are ultrasonically welded to gather and fix the multiple lugs, forming a first welding mark 901; then the lugs are put into the grooves 203 on the pole posts 2, and the lugs and the pole posts are laser welded to fix the lugs on the pole posts 2 and form a second welding mark 902. The first welding mark 901 is an ultrasonic welding mark, and the second welding mark 902 is a laser welding mark. The second welding mark 902 is a re-welding mark based on the first welding mark 901, and the second welding mark 902 can have multiple rows. The multiple rows of the second welding mark 902 are arranged in parallel and at intervals to increase the stability of the connection between the lugs and the pole posts 2.

[0068] In addition, in other embodiments, the number of the pole groups 7 is multiple, the positive lugs of the multiple pole groups 7 are welded with one positive pole post, and the negative lugs of the multiple pole groups 7 are welded with one negative pole post. Through one group of pole posts, simultaneous connection with multiple pole groups is realized, the capacity of the battery is expanded, and the assembly and fixation of the pole groups 7 and the pole posts 2 are facilitated. One group of pole posts refers to one positive pole post and one negative pole post. Optionally, as shown in FIG. 15, the number of the pole groups 7 is two.

[0069] The following describes the experimental results of testing batteries with different parameter values for experimental verification.

[0070] Table 1 Battery test results corresponding to different values of weld penetration A

[0071] As can be seen from Table 1, for the batteries of implementation cases 1 to 3, the weld penetration A of the weld 10 along the axial direction of the pole 2 all satisfy the limited range of 1.2PM / D≤A≤0.8T, and the test results of the batteries of implementation cases 1 to 3 are: the battery passes the helium test (OK), the pole does not leak under the condition of each pressure of 1.2 MPa inside and outside the pole, the weld is not damaged, and the sealing ring does not melt after disassembly, that is, the battery can pass each test, and the battery performance is good. However, for the battery of comparative case 1, the weld penetration A of the weld 10 along the axial direction of the pole 2 is 1.8 mm, which is greater than 0.8T (i.e. 1.6 mm) and does not fall within the range defined in the present application. Although the helium test is OK, the pole does not leak under the condition of each pressure of 1.2 MPa inside and outside the pole, and the weld is not damaged, but the sealing ring melts after disassembly, which has the risk of insulation and sealing failure, and is not recommended for use.

[0072] In summary, when the weld penetration A of the weld 10 along the axial direction of the pole 2 satisfies 1.2PM / D≤A≤0.8T, it can not only ensure that the weld has sufficient weld strength and ensure the compression effect of the weld ring 4 on the sealing ring 3, but also avoid the heat generated by the weld from melting the sealing ring 3, thereby ensuring the air tightness and improving the safety performance of the battery.

[0073] Batteries with different values of the full life cycle pressure P of the sealing ring 3, the ratio M of the contact area between the sealing ring 3 and the weld ring 4 to the circumference of the inner ring of the weld ring 4, the shear strength D of the weld 10, and the thickness T of the weld ring 4 were tested, and Table 2 shows the test results of the implementation cases, and Table 3 shows the test results of the comparative cases.

[0074] Table 2 Test results of implementation cases corresponding to different values of P, M, D, and T

[0075] As can be seen from Table 2, for the batteries of the implementation cases 4 to 16, the full life cycle pressure P of the sealing ring 3, the ratio M of the contact area where the sealing ring 3 and the welding ring 4 are in contact to the circumference of the inner ring of the welding ring 4, the shear strength D of the weld 10, and the thickness T of the welding ring 4 are all within the ranges defined in the present application, and the welding penetration A of the weld 10 along the axial direction of the pole 2 satisfies the defined range of 1.2PM / D≤A≤0.8T. The test results of the batteries of the implementation cases 4 to 16 tested are as follows: the battery helium test is OK (pass); the pole is not leaked after each of the inner and outer poles is pressurized by 1.2 MPa, and the weld is not damaged; and the sealing ring is not melted after disassembly. That is, the batteries can pass each test, and the battery performance is good.

[0076] Table 3 Test results of comparative cases corresponding to different values of P, M, D, and T

[0077] As can be seen from Table 3, for the battery of comparative case 2, the full life cycle pressure P of the sealing ring 3 is 35 MPa, greater than 30 MPa, not within the range defined in the application, although the battery is helium OK, the pole is not leaked under the condition of each pressure of 1.2 MPa inside and outside the pole, the weld is not damaged, and the sealing ring does not appear to be melted after disassembly, but the sealing ring bears a large pressure, the reliability is reduced, and it is not recommended to use; for the battery of comparative case 3, the full life cycle pressure P of the sealing ring 3 is 0.5 MPa, less than 1.3 MPa, not within the range defined in the application, helium is NG (not pass), the pole is leaked under the condition of each pressure of 1.2 MPa inside and outside the pole, the weld is not damaged, and the sealing ring does not appear to be melted after disassembly, that is, the air tightness of the pole is poor, and the battery is unqualified; for the battery of comparative case 4, the ratio M of the contact area of the sealing ring 3 and the welding ring 4 to the circumference of the inner ring of the welding ring 4 is 0.3, less than 0.6, not within the range defined in the application, helium is OK, the pole is leaked under the condition of each pressure of 1.2 MPa inside and outside the pole, the weld is not damaged, and the sealing ring does not appear to be melted after disassembly, the air tightness is poor, and the battery is unqualified; for the battery of comparative case 5, M is 3.5, greater than 3, not within the range defined in the application, although helium is OK, the pole is not leaked under the condition of each pressure of 1.2 MPa inside and outside the pole, the weld is not damaged, and the sealing ring does not appear to be melted after disassembly, but the cost of the sealing ring increases more, and it is not recommended to use; for the battery of comparative case 6, the shear strength D of the weld 10 is 30 MPa, less than 50 MPa, not within the range defined in the application, the weld strength is small, the weld cracking occurs, and the battery is unqualified; for the battery of comparative case 7, the thickness T of the welding ring 4 is 6 mm, greater than 5 mm, not within the range defined in the application, although helium is OK, the pole is not leaked under the condition of each pressure of 1.2 MPa inside and outside the pole, the weld is not damaged, and the sealing ring does not appear to be melted after disassembly, but the welding ring is thick, which is not conducive to the improvement of the volume energy density, and it is not recommended to use; for the battery of comparative case 8, the thickness T of the welding ring 4 is 0.6 mm, less than 0.8 mm, not within the range defined in the application, the welding ring is thin, and slight deformation occurs after assembly and welding, and it is not recommended to use.

[0078] In summary, when the full life cycle pressure P of the sealing ring 3, the ratio M of the contact area of the sealing ring 3 and the welding ring 4 to the circumference of the inner ring of the welding ring 4, the shear strength D of the weld 10, and the thickness T of the welding ring 4 are all within the range defined in the application, the battery is qualified. It can be popularized and applied.

[0079] In addition, in combination with the analysis of Tables 1 to 3, it can be seen that, for the battery of Comparative Example 1, although the full-life cycle pressure P of the sealing ring 3, the ratio M of the contact area where the sealing ring 3 and the welding ring 4 are in contact to the circumference of the inner ring of the welding ring 4, the shear strength D of the weld 10, and the thickness T of the welding ring 4 are all within the ranges defined in the present application, the welding penetration A of the weld 10 along the axial direction of the pole 2 is 1.8 mm, which is greater than 0.8T (i.e. 1.6 mm) and is not within the range defined in the present application. Although the helium test is OK, the pole does not leak under the condition of pressurizing the inside and outside of the pole by 1.2 MPa, and the weld is not damaged, but the sealing ring melts after disassembly, which has the risk of sealing and insulation failure, and is not recommended for use. In summary, when the full-life cycle pressure P of the sealing ring 3, the ratio M of the contact area where the sealing ring 3 and the welding ring 4 are in contact to the circumference of the inner ring of the welding ring 4, the shear strength D of the weld 10, and the thickness T of the welding ring 4 are all within the ranges defined in the present application, and the welding penetration A of the weld 10 along the axial direction of the pole 2 satisfies the defined range of 1.2PM / D≤A≤0.8T, the battery can not only ensure the sealing and insulation of the battery, but also minimize the cost, and is also conducive to improving the volumetric energy density of the battery, and the battery is qualified.

[0080] Although the embodiments of the present application are described in combination with the drawings, various modifications and variations can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A cover assembly, characterized by The utility model relates to a sealing structure of a battery, which comprises: a cover plate with a first through hole; a pole including a first pole segment and a second pole segment fixedly connected, the outer contour of the first pole segment being larger than that of the second pole segment, the second pole segment being arranged in the first through hole, and the first pole segment being located on one side of the cover plate; a sealing ring arranged on the second pole segment, the sealing ring being located on the side of the cover plate away from the first pole segment; a welding ring arranged on the second pole segment, the welding ring being located on the side of the sealing ring away from the cover plate and abutting against the sealing ring, at least part of the area on the inner wall of the welding ring being welded with part of the area on the outer circumferential surface of the second pole segment to form a weld, and the weld having a welding penetration A along the axial direction of the pole satisfying the formula: 1.2PM / D≤A≤0.8T, wherein P is the full life cycle pressure of the sealing ring, M is the ratio of the contact area of the sealing ring and the welding ring to the circumference of the inner ring of the welding ring, D is the shear strength of the weld, and T is the dimension of the welding ring along the direction of the center line thereof. The full life cycle pressure P of the sealing ring ranges from 1.3 MPa to 30 MPa.

2. The cover plate assembly of claim 1, wherein, The ratio M of the contact area of the sealing ring and the welding ring to the circumference of the inner ring of the welding ring ranges from 0.6 mm to 3 mm. The shear strength D of the weld ranges from 50 MPa to 2000 MPa. The dimension T of the welding ring along the direction of the center line thereof ranges from 0.8 mm to 5 mm. The full life cycle pressure P of the sealing ring ranges from 1.3 MPa to 30 MPa.

3. The cover plate assembly of claim 1, wherein, Or, the ratio M of the contact area of the sealing ring and the welding ring to the circumference of the inner ring of the welding ring ranges from 0.6 mm to 3 mm. Or, the shear strength D of the weld ranges from 50 MPa to 2000 MPa. Or, the dimension T of the welding ring along the direction of the center line thereof ranges from 0.8 mm to 5 mm. The end of the second pole segment away from the first pole segment is configured with a groove, the groove is recessed from part of the area on the end face of the second pole segment towards the direction close to the first pole segment, and the groove is adapted to provide accommodation space for the lug on the pole group.

4. The cover plate assembly of claim 1, wherein, The thickness of the side wall of the groove is K, wherein the value range of K is 0.8 mm to 3 mm.

5. The cover plate assembly of claim 4, wherein, The surface of the side of the welding ring away from the first pole segment is flush with the end face of the second pole segment away from the first pole segment, and the weld extends from the end face of the second pole segment away from the first pole segment towards the direction close to the first pole segment.

6. The cover plate assembly of claim 5, wherein, The projection of the weld on the plane where the end face of the second pole segment away from the first pole segment is located has a width V, wherein the value range of V is 0.5 mm to 0.9 K.

7. The cover plate assembly of claim 6, wherein, ​ 8. The cover plate assembly of any one of claims 1-7, wherein, The cover plate assembly further comprises a lower plastic part arranged on the side of the cover plate away from the first post segment, a second through hole is formed in the lower plastic part, the second post segment is arranged in the second through hole, the profile size of the second through hole is smaller than the size of the outer ring of the welding ring and larger than the size of the inner ring of the welding ring, a lap portion is formed on the body of the lower plastic part near the edge of the second through hole, the lap portion is located between the welding ring and the cover plate, the lap portion is lapped with the outer ring edge of the welding ring and the lap portion is located on the side of the welding ring facing the cover plate, the lap portion forms an annular shape, the ring width of the annular shape formed by the lap portion is W, wherein the value range of W is 0.8mm-5mm.

9. The cover plate assembly of claim 8, wherein, The cover plate is provided with a recess, the recess is recessed from the surface of the side of the cover plate away from the first post segment in the direction close to the first post segment, the first through hole is formed in the recess, the cross section of the lap portion is "L" type, the lap portion is located in the recess, and the welding ring is located in the space formed between the first side and the second side of the lap portion.

10. A battery, characterized by Comprise: a housing having an open end; a pole group arranged in the housing; the cover plate assembly of any one of claims 1 to 9, the cover plate assembly is arranged at the open end of the housing to close the housing.

11. The battery of claim 10, wherein, The pole post comprises a positive pole post and a negative pole post; The number of pole groups is one, the positive pole lug of the pole group is welded with the positive pole post, and the negative pole lug of the pole group is welded with the negative pole post; or the number of pole groups is multiple, the positive pole lug of multiple pole groups is welded with one positive pole post, and the negative pole lug of multiple pole groups is welded with one negative pole post.

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