Cover plate, battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a cover plate, a battery cell and a battery pack, the cover plate satisfies 0.5 < = b / a < = 0.8, so that the distance between the side walls of the two ends of a cylinder part in the length direction and the hole wall of a riveting hole before riveting can be reduced, after the cylinder part is riveted and expanded, the two ends of the cylinder part in the length direction can be attached to the inner wall of the riveting hole, and the riveting quality is improved. The influence of uneven material expansion in the length direction of the column part can be neutralized, the fitting degree of the side walls of the two ends of the column part in the length direction and the hole wall of the riveting block can be ensured, and the welding firmness between the column part and the riveting block can be ensured, so that the conductivity between the pole and the riveting block can be improved, and the stability of the internal resistance of the cover plate can be improved; meanwhile, b / a is larger than or equal to 0.5, so that the large difference between the width of the step surfaces of the first steps on the two sides of the riveting hole in the length direction and the width direction can be prevented, and the situation that the riveting block is extruded and deformed due to serious material expansion on the two sides of the cylinder part in the length direction is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a cover plate, a battery cell and a battery pack. Background Art

[0002] like Figure 1 As shown, the cover plate using the pole riveting fixation method includes a riveting block 2', a first insulating member, a cover plate body 1', a second insulating member, a pole 3' and a sealing ring. The pole 3' includes a base plate and a column portion. The pole base plate and the riveting block clamp the cover plate components therebetween. The top of the column portion is riveted to the riveting block, and then the connection between the pole and the riveting block is reinforced by laser welding.

[0003] Existing columns are typically cylindrical. For cells with narrow, elongated covers and high current requirements, increasing the current capacity of the cells by increasing the diameter of the cylindrical column is not feasible due to the narrow width of the cover body. Instead, the column must be enlarged along the length of the cover body, resulting in a narrow, elongated column. This non-circular cross-section of the pole can easily lead to uneven material expansion during riveting, preventing the column from effectively fitting into the rivet block after riveting. Laser welding of the column and rivet block can easily result in cold welds and unstable internal resistance. Summary of the Invention

[0004] In view of this, the present invention provides a cover plate, a battery cell and a battery pack to solve the problem in the prior art that the pole column is narrow and long, and the material expands unevenly during riveting, resulting in easy cold welding and unstable internal resistance between the pole column and the riveted block.

[0005] In a first aspect, the present invention provides a cover plate, comprising:

[0006] The cover body is provided with a mounting hole;

[0007] A rivet block having a rivet hole and disposed on the outer side of a surface of the cover plate body facing the outer side of the cover plate; the length of the rivet hole is greater than the width of the rivet hole; a first step is disposed on the inner wall of the rivet hole; the width of the step surface of the first step on either side of the two ends in the length direction of the rivet hole is less than the width of the step surface of the first step on either side of the two ends in the width direction of the rivet hole; the minimum width of the step surface of the first step at both ends in the length direction of the rivet hole is b, and the width of the step surface of the first step at both ends in the width direction of the rivet hole is a, 0.5≤b / a≤0.8, and the units of a and b are mm;

[0008] The pole comprises a base plate and a column portion provided on the base plate, the column portion passes through the mounting hole and the rivet hole and is riveted to the rivet block, the base plate is located on the inner side of the other side surface of the cover body facing the inner side of the cover plate; the column portion extends in the same direction as the rivet block and the length of the column portion is greater than the width of the column portion, and the cross-sectional shape of the column portion is adapted to the shape of the rivet hole.

[0009] Beneficial effect: After the cover plate of this structure is assembled, the column part passes through the rivet hole, and the peripheral side wall of the column part is arranged parallel to the side wall of the rivet hole. The width of the step surface of the first step on either side of the two ends in the length direction of the rivet hole is smaller than the width of the step surface of the first step on either side of the two ends in the width direction of the rivet hole, and the minimum width b of the step surface of the first step at both ends in the length direction of the rivet hole and the width a of the step surface of the first step at both ends in the width direction of the rivet hole meet 0.5≤b / a≤0.8. In this way, compared with the same step surface width of the first step at various places in the circumference, the distance between the side walls at both ends of the length direction of the column part and the wall of the rivet hole can be reduced before riveting, and the gap that needs to be filled between the two is reduced. After the column part is riveted and expanded, it can be made The two ends of the column part in the length direction are fitted on the inner wall of the rivet hole, which can neutralize the influence of uneven material expansion in the length direction of the column part, ensure the fit between the side walls at both ends of the column part in the length direction and the wall of the rivet block hole, avoid the gap between the side walls at both ends of the column part in the length direction and the rivet block being too large, resulting in a cold weld between the pole and the rivet block, and ensure the welding firmness between the column part and the rivet block, thereby improving the conductivity between the pole and the rivet block, and improving the stability of the internal resistance of the cover plate; at the same time, 0.5≤b / a, which can prevent the step surface width of the first step on both sides of the length direction and the width direction of the rivet hole from being too different, and avoid serious material expansion on both sides of the length direction of the column part causing the rivet block to be squeezed and deformed.

[0010] In an optional embodiment, the rivet hole includes a central smooth area and arc-shaped areas provided at both ends of the central smooth area, and the hole wall of the rivet hole at the central smooth area transitions smoothly to the hole wall of the rivet hole at the arc-shaped areas.

[0011] Beneficial effects: This can improve the uniformity of material expansion at various circumferential positions of the column during riveting, ensure that various circumferential positions of the column can effectively fit with the riveted block, and then after laser welding the column and the riveted block, the reliability of the welding between the two can be guaranteed, the conductive effect of the pole and the riveted block can be guaranteed, and the internal resistance and stability of the battery operation can be guaranteed.

[0012] In an optional embodiment, the arc-shaped area is a semicircular arc, the middle smooth area is a rectangle, the diameter of the semicircular arc is equal to the width of the middle smooth area; along the circumference of the semicircular arc, from the middle smooth area to the circumferential middle of the arc-shaped area, the width of the step surface of the first step gradually decreases; the cross-section of the columnar portion is runway-shaped.

[0013] In an optional embodiment, 0.2 mm ≤ a ≤ 1.25 mm.

[0014] Beneficial effects: This can ensure that the first step in the middle smooth area has a sufficient width, which is convenient for forming the first step, and at the same time ensure the supporting effect of the first step in the middle smooth area of ​​the rivet block on the pole, and can also prevent the rivet block from being stretched toward the circumferential outside of the rivet hole after the column part expands, prevent the rivet block from deforming, and ensure the size of the rivet block; in addition, it can also prevent the step surface of the first step in the middle smooth area from being too wide, and ensure that the circumferential side wall of the column part can fit on the hole wall of the rivet hole in the middle smooth area after the material expands, thereby ensuring the reliability of the welding between the pole and the rivet block after welding, and ensuring the stability of the internal resistance of the battery cell and the battery performance.

[0015] In an optional embodiment, 0.2 mm ≤ b ≤ 1 mm.

[0016] In an optional embodiment, a pre-rivet groove is provided on a surface of the column portion facing the outer side of the cover plate, and the long side of the pre-rivet groove extends in the same direction as the long side of the column portion.

[0017] In an optional embodiment, a second step is provided on the inner wall of the rivet hole between the first step and the surface of the side of the rivet block facing the outer side of the cover plate, and the width of the step surface of the second step is the same at all circumferential locations; the width of the step surface of the second step is c, and the height of the second step is h, 0.5mm≤c≤1.5mm, 0.2mm≤h≤0.5mm.

[0018] In an optional embodiment, the thickness between the step surface of the first step and the other side surface of the riveting block facing the inner side of the cover plate is t1, 0.5mm≤t1≤2mm;

[0019] And / or, the total thickness of the riveting block is t, 1.5 mm≤t≤3.5 mm.

[0020] In a second aspect, the present invention further provides a battery cell comprising a housing and a cover plate as described above, wherein the housing has an opening and the cover plate is disposed over the opening. The battery cell including the cover plate has the same technical effects as the cover plate and will not be further described here.

[0021] In a third aspect, the present invention further provides a battery pack comprising the aforementioned battery cell. The battery pack includes a cover plate, which has the same technical effects as the cover plate and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a schematic diagram of the three-dimensional structure of the cover plate described in the background technology of the present invention;

[0024] Figure 2 This is a schematic diagram of the three-dimensional structure of a cover plate according to an embodiment of the present invention;

[0025] Figure 3 for Figure 2 a top view of the cover plate shown;

[0026] Figure 4 for Figure 3 AA sectional view;

[0027] Figure 5 for Figure 4 A partial enlarged schematic diagram;

[0028] Figure 6 for Figure 3 BB cross-sectional view;

[0029] Figure 7 for Figure 2 Top view of the middle riveting block;

[0030] Figure 8 for Figure 2 Schematic diagram of the three-dimensional structure of the middle riveting block;

[0031] Figure 9 for Figure 2 Schematic diagram of the three-dimensional structure of the middle pole;

[0032] Figure 10 for Figure 2 Exploded view of the cover shown.

[0033] Description of reference numerals:

[0034] 1', cover plate body; 2', riveting block; 3', pole;

[0035] 1. Cover plate body; 2. Riveting block; 21. Riveting hole; 211. First step; 212. Middle smooth area; 213. Arc area; 214. Second step; 3. Pole; 31. Bottom plate; 32. Column; 321. Pre-rivet groove; 4. First insulating member; 5. Second insulating member; 6. Sealing member. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0037] like Figure 1 As shown, the cover plate fixed by the pole riveting method includes a riveting block 2', a first insulating member, a cover plate body 1', a second insulating member, a pole 3' and a sealing ring. The pole 3' includes a base plate and a column portion. The column portion is generally cylindrical. For a battery cell with a narrow and long cover plate and a large overcurrent requirement, since the width of the cover plate body is narrow, it is impossible to increase the overcurrent capacity of the battery cell by increasing the diameter of the cylindrical column portion. The size of the column portion can only be increased in the length direction of the cover plate body, thus forming a narrow and long column portion. For this type of pole with a non-circular cross section, when riveting, the riveting punch applies pressure outward from the middle area of ​​the column portion to expand the material. Since the length of the column portion is greater than its width, the two ends of the column portion in the length direction do not expand outward enough. A rivet hole is provided on the rivet block. Before riveting, the peripheral side wall of the column part is spaced apart from the side wall of the rivet hole. The two ends of the column part in the length direction do not expand outward enough, resulting in the two ends of the column part in the length direction being unable to fit on the side wall of the rivet hole after expansion, resulting in a gap between the column part and the side wall of the rivet hole. After laser welding the column part and the rivet block, cold welding and unstable internal resistance are likely to occur.

[0038] The following combination Figures 2 to 10 , describing embodiments of the present invention.

[0039] According to an embodiment of the present invention, on one hand, a cover plate is provided, including a cover plate body 1 , a riveting block 2 and a pole 3 .

[0040] Among them, the cover body 1 is provided with a mounting hole; the rivet block 2 is provided with a rivet hole 21 and is provided on the outer side of the cover body 1 facing the outer side of the cover; the length of the rivet hole 21 is greater than the width of the rivet hole 21; a first step 211 is provided on the inner wall of the rivet hole 21; the width of the step surface of the first step 211 on either side of the two ends in the length direction of the rivet hole 21 is smaller than the width of the step surface of the first step 211 on either side of the two ends in the width direction of the rivet hole 21, and the minimum width of the step surface of the first step 211 at both ends in the length direction of the rivet hole 21 is b, and the width of the step surface of the first step 211 at both ends in the width direction of the rivet hole 21 is b. The width of the step surface of the first step 211 at both ends of the width direction of 21 is a, 0.5≤b / a≤0.8, and the units of a and b are mm; the pole 3 includes a base plate 31 and a column portion 32 provided on the base plate 31, the column portion 32 is penetrated by the mounting hole and the rivet hole 21 and is riveted to the rivet block 2, and the base plate 31 is located on the inner side of the other side surface of the cover body 1 facing the inner side of the cover body; the column portion 32 extends in the same direction as the rivet block 2 and the length of the column portion 32 is greater than the width of the column portion 32, and the cross-sectional shape of the column portion 32 is adapted to the shape of the rivet hole 21.

[0041] The cover plate of this structure, after the cover plate is assembled, the column part 32 passes through the rivet hole 21, and the peripheral side wall of the column part 32 is arranged parallel to the side wall of the rivet hole 21, and the width of the step surface of the first step 211 on either side of the two ends in the length direction of the rivet hole 21 is smaller than the width of the step surface of the first step 211 on either side of the two ends in the width direction of the rivet hole 21, and the minimum width b of the step surface of the first step 211 at both ends in the length direction of the rivet hole 21 and the width a of the step surface of the first step 211 at both ends in the width direction of the rivet hole 21 meet 0.5≤b / a≤0.8. In this way, compared with the first step 211 having the same step surface width at all places in the circumference, the distance between the side walls at both ends in the length direction of the column part 32 and the hole wall of the rivet hole 21 before riveting can be reduced, and the gap that needs to be filled between the two is reduced. After the column part 32 is riveted and expanded, This allows the two ends of the column portion 32 in the length direction to fit on the inner wall of the rivet hole 21, which can neutralize the influence of uneven material expansion in the length direction of the column portion 32, ensure the fit between the side walls at both ends of the column portion 32 in the length direction and the hole wall of the rivet block 2, and avoid excessive gaps between the side walls at both ends of the column portion 32 in the length direction and the rivet block 2, which may cause a cold weld between the pole 3 and the rivet block 2, and ensure the welding firmness between the column portion 32 and the rivet block 2, thereby improving the conductivity between the pole 3 and the rivet block 2 and improving the stability of the internal resistance of the cover plate; at the same time, b / a≥0.5, which can prevent the step surface width of the first step 211 on both sides of the length direction and the width direction of the rivet hole 21 from being too different, and avoid serious material expansion on both sides of the length direction of the column portion 32, which may cause the rivet block 2 to be squeezed and deformed.

[0042] The rivet hole 21 includes a central smooth area 212 and arc-shaped areas 213 provided at both ends of the central smooth area 212. The hole wall of the rivet hole 21 at the central smooth area 212 transitions smoothly to the hole wall of the rivet hole 21 at the arc-shaped area 213. The cross-sectional shape of the column portion 32 is adapted to the shape of the rivet hole 21, that is, a smooth area is provided in the middle of the column portion 32 in the length direction, and arc-shaped areas are provided at both ends of the smooth area. The smooth area of ​​the column portion 32 and the side walls of the arc-shaped area transition smoothly. The rivet block 2 of the first part is fixed with the rivet 32 ​​at the bottom, and the rivet 32 ​​at the bottom is fixed with the rivet 32 ​​at the bottom.

[0043] In some optional embodiments, such as Figure 7 and Figure 8 As shown, the arc-shaped area 213 is a semicircular arc, the middle smooth area 212 is a rectangle, and the diameter of the semicircular arc is equal to the width of the middle smooth area 212; along the circumference of the semicircular arc, from the middle smooth area 212 to the circumferential middle position of the arc-shaped area 213, the width of the step surface of the first step 211 gradually decreases, and the width of the step surface of the first step 211 at the circumferential middle position of the semicircular arc is the smallest, and the step surface width value at this location is b; the cross section of the column portion 32 is correspondingly runway-shaped, that is, the middle portion of the cross section of the column portion 32 is rectangular, and the two ends of the cross section in the length direction are semicircular. Along the circumference of the semicircular arc, from the middle smooth area 212 to the circumferential middle of the first step 211, the width of the step surface of the first step 211 gradually decreases, and the column portion 32 at the corresponding position of the circumferential middle position of the semicircular arc is farthest from the central area of ​​the column portion 32. It is more difficult to expand the column portion 32 in this area, and the expanded material is relatively small. Along the circumference of the semicircular area of ​​the column portion 32, the expanded material from the end to its circumferential center is also gradually reduced. The width of the first step 211 corresponds to the amount of expanded material area of ​​the column portion 32 in the circumferential direction. In this way, it can be ensured that the two ends of the column portion 32 in the length direction are riveted and expanded and fit with the side wall of the rivet hole 21, which can ensure the reliability of the welding between the column portion 32 and the riveted block 2, and can ensure the conductivity between the pole 3 and the riveted block 2, thereby ensuring the stability of the internal resistance of the cover plate and the stability of the battery operation.

[0044] In other embodiments, the middle smooth area 212 may also be in the shape of an ellipse with open ends on the long axis, and the arc-shaped area 213 may be in the shape of a non-semicircle with an arc in the circumference.

[0045] like Figure 5 and Figure 6 As shown, after the column portion 32 is riveted, its expanded and deformed area is supported on the stepped surface of the first step 211 of the riveting block 2. If the width of the first step 211 is too small, it will be inconvenient to form the first step 211 during the production of the riveting block 2, and the riveting block 2 will also be unable to effectively support the pole 3, which will affect the connection strength between the column portion 32 and the riveting block 2 after riveting. In addition, after the column portion 32 is riveted, its expanded and deformed area must fill the stepped surface of the first step 211, so that the circumferential side wall of the column portion 32 abuts the hole wall of the riveting hole 21, ensuring the fit between the column portion 32 and the riveting block 2. If the step surface of the first step 211 is wider, the distance between the circumferential side wall of the column portion 32 and the hole wall of the rivet hole 21 before riveting is farther, and it is difficult for the column portion 32 to fill the first step 211 after the material is expanded, resulting in a gap between the circumferential side wall of the column portion 32 and the hole wall of the rivet block 2, thereby causing a cold weld between the column portion 32 and the rivet block 2 after welding. In order to avoid these problems, in some embodiments, 0.2mm≤a≤1.25mm, which can ensure that the first step 211 in the middle smooth area 212 has a sufficient width to facilitate the formation of the first step 211, and at the same time ensure the supporting effect of the first step 211 in the middle smooth area 212 of the rivet block 2 on the pole 3, and can also prevent the column part 32 from stretching the rivet block 2 toward the circumferential outside of the rivet hole 21 after the material is expanded, prevent the rivet block 2 from deforming, and ensure the size of the rivet block 2; in addition, it can also prevent the step surface of the first step 211 in the middle smooth area 212 from being too wide, and ensure that the circumferential side wall of the column part 32 can be fitted on the hole wall of the rivet hole 21 in the middle smooth area 212 after the material is expanded, thereby ensuring the reliability of the welding between the pole 3 and the rivet block 2 after welding, and ensuring the stability of the internal resistance of the battery cell and the battery performance.

[0046] Similarly, in some embodiments, as Figure 5 As shown, 0.2mm≤b≤1mm, which can ensure the width of the first step 211 in the arc area 213, facilitate the formation of the first step 211, and at the same time ensure the supporting effect of the first step 211 in the arc area 213 of the rivet block 2 on the pole 3, and can also prevent the column part 32 from stretching the rivet block 2 toward the circumferential outside of the rivet hole 21 after the material is expanded, prevent the rivet block 2 from deforming, and ensure the size of the rivet block 2; in addition, it can also prevent the step surface of the first step 211 in the arc area 213 from being too wide, and ensure that the circumferential side wall of the column part 32 can fit on the hole wall of the rivet hole 21 in the arc area 213 after the material is expanded, so as to further ensure the reliability of the welding between the pole 3 and the rivet block 2 after welding, and further improve the stability of the internal resistance of the battery cell and the performance of the battery.

[0047] Riveted blocks 2 with different a and b values ​​and different b / a ratios were designed and assembled into a cover plate. The riveted blocks 2 were observed during the riveting and welding process of the pole 3 and the internal resistance of the cover plate was measured. The test results are shown in Table 1.

[0048] Table 1

[0049]

[0050] It can be seen from Examples 1 to 7 that when b / a satisfies 0.5≤b / a≤0.8, the distance between the side walls of the two ends of the column portion 32 in the length direction and the wall of the riveting hole 21 is reduced before riveting. After the column portion 32 is riveted and expanded, the two ends of the column portion 32 in the length direction can be fitted on the inner wall of the riveting hole 21. There is basically no gap between the wall of the riveting hole 21 and the column portion 32 at the middle smooth area 212 and the arcuate area 213, and no cold welding occurs when the pole 3 is welded to the riveted block 2. It can be seen from Comparative Example 1 that when b / a < 0.5, the distance between the first step 211 at the arcuate area 213 and the middle smooth area 212 is less than 0. The step surface widths differ greatly, the first step 211 at the corresponding position of the arc area 213 has severe material expansion, the rivet block 2 is squeezed and deformed, the pole 3 and the rivet block 2 are poorly welded, and the internal resistance of the cover plate does not meet the requirements; it can be seen from comparative example 2 that when b / a>0.8, the step surface width of the first step 211 at the arc area 213 is not significantly reduced, and the step surface width aberration between the arc area 213 and the first step 211 at the middle smooth area 212 is small. After the column part 32 is riveted, there is a gap between the hole wall of the rivet block 2 at the arc area 213 and the side wall of the column part 32, and a cold weld occurs after welding, and the welding internal resistance does not meet the requirements. It can be seen from Comparative Example 3 that when b is less than 0.2 mm, the step surface width of the first step 211 at the arc-shaped area 213 is too small, the step feature of the first step 211 of the rivet block 2 is not obvious, it is inconvenient to form the first step 211, and the connection strength between the pole 3 and the rivet block 2 is insufficient; it can be seen from Comparative Example 4 that when b is less than 0.2 mm and a is less than 0.2 mm, the width of the step surface of the first step 211 in the entire circumference is narrow, the step feature of the first step 211 of the rivet block 2 is not obvious, it is inconvenient to form the first step 211, and the connection strength between the pole 3 and the rivet block 2 is insufficient; it can be seen from Comparative Example 5 that when a is less than 0.2 mm, the step surface width of the first step 211 at the middle smooth area 212 is too small, the step feature of the first step 211 is not obvious, it is inconvenient to form the first step 211, and the connection strength between the pole 3 and the rivet block 2 is insufficient.

[0051] like Figure 5 and Figure 6As shown, in some embodiments, a pre-rivet groove 321 is provided on one side of the column portion 32 facing the outer side of the cover plate, with the long side of the pre-rivet groove 321 extending in the same direction as the long side of the column portion 32. When riveting the terminal 3, the riveting punch presses downward on the pre-rivet groove 321 to apply force, facilitating the expansion and forming of the column portion 32.

[0052] like Figure 9 As shown, in some embodiments, before riveting, the cross-sectional shape of the rivet groove is the same as the cross-sectional shape of the column portion 32 , and the shape of the rivet punch corresponds to the pre-rivet groove 321 .

[0053] In some optional embodiments, before riveting, the side walls of the rivet groove are inclined, and from the bottom of the rivet groove to the groove opening of the rivet groove, the side walls of the rivet groove are inclined toward the circumferential outside of the column portion 32, so that the groove opening of the rivet groove is larger than its groove bottom. This arrangement is more conducive to the riveting punch squeezing the column portion 32 outward, thereby facilitating the column portion 32 to expand outward.

[0054] In some embodiments, as Figure 5 and Figure 6 As shown, before riveting, the angle between the side wall of the riveting groove and the vertical plane (that is, the inclination angle of the side wall of the riveting groove) is between 30° and 60°. This setting is more conducive to riveting the column part 32, and the column part 32 is in a good forming state. It can also prevent the riveting groove from inclining too much, causing the column part 32 to transition outward and expand, and can prevent excessive expansion from squeezing the riveted block 2, and can prevent the riveted block 2 from deforming.

[0055] like Figures 5 to 8 As shown, in some embodiments, a second step 214 is provided on the inner wall of the rivet hole 21 between the first step 211 and the surface of the rivet block 2 facing the outer side of the cover plate. The width of the step surface of the second step 214 is the same at all locations along the circumference. The width of the step surface of the second step 214 is c, and the height of the second step 214 is h, where 0.5mm≤c≤1.5mm, and 0.2mm≤h≤0.5mm. After the column portion 32 is riveted and expanded, it is welded to the rivet block 2. The weld mark has a certain thickness and width, and the groove formed in the second step 214 is used to accommodate the weld mark. c≥0.5mm, h≥0.2mm, which can ensure the height and width of the second step 214, so that it has sufficient space to accommodate the weld mark, which can effectively prevent the weld mark from leaking, thereby ensuring the appearance of the battery cell and at the same time ensuring the flatness of the surface of the side of the rivet block 2 facing the outside of the cover plate, without affecting the subsequent welding of the rivet block 2 and the bus bar; c≤1.5mm, which can avoid the width of the step surface of the second step 214 occupying too much space in the length direction of the cover plate, especially in the width direction of the cover plate, and h≤0.5mm, which can prevent the height h of the second step 214 from being too high and wasting space in the height direction of the rivet block.

[0056] like Figure 5As shown, in some embodiments, the thickness between the step surface of the first step 211 and the other side surface of the rivet block 2 facing the inner side of the cover plate is t1, 0.5mm≤t1≤2mm, so that the thickness of the rivet block 2 in the area below the first step 211 can be guaranteed, and the strength of the rivet block 2 can be guaranteed, thereby ensuring the supporting effect of the rivet block 2 on the pole 3, and further ensuring the reliability of the connection between the pole 3 and the rivet block 2; at the same time, it can also avoid the thickness between the step surface of the first step 211 and the other side surface of the rivet block 2 facing the inner side of the cover plate being too large, avoid redundant design, avoid increased cost of the rivet block, and prevent the rivet block from occupying too much space in the height direction of the battery cell.

[0057] In some embodiments, as Figure 5 As shown, the total thickness of the rivet block 2 is t, 1.5mm≤t≤3.5mm. The thicker the rivet block 2 is, the better its strength is, and the better the support of the rivet block 2 to the pole 3 is. However, when the thickness of the rivet block 2 is too thick, the space it occupies in the thickness direction of the cover is too large, which will cause the overall thickness of the cover to increase, which will cause space waste and affect the volume energy density of the battery cell. Therefore, in order to avoid this problem, the thickness of the rivet block 2 is t≤3.5mm, so as to prevent the thickness of the rivet block 2 from being too large and ensure the volume energy density of the battery cell; at the same time, 1.5mm≤t, which can prevent the thickness of the rivet block from being too small, ensure the strength of the rivet block, and avoid the welding penetration of the rivet block when welding the rivet block to the bar, causing the first insulating member 4 to melt.

[0058] In some embodiments, as Figures 4 to 6 As shown, the cover plate further includes a first insulating member 4, a second insulating member 5, and a sealing member 6. The first insulating member 4 is provided on the side surface of the cover plate body 1 facing the outside of the cover plate; the rivet block 2 is provided on the side surface of the first insulating member 4 facing the outside of the cover plate; the second insulating member 5 is provided on the other side surface of the cover plate body 1 facing the inside of the cover plate; the bottom plate 31 is provided on the inner side of the other side surface of the second insulating member 5 facing the inside of the cover plate; the sealing member 6 is provided between the cover plate body 1 and the pole 3, with the side surface of the bottom plate 31 facing the outside of the cover plate abutting against the sealing member 6, and the column portion 32 passes through the second insulating member 5, the cover plate body 1, the first insulating member 4, and the rivet block 2 and is riveted to the rivet block 2.

[0059] The cover plate can be used for any battery cell with a narrow and long cover plate, such as blade battery cells and square shell battery cells.

[0060] According to an embodiment of the present invention, on the other hand, a battery cell is provided, comprising a housing and the cover plate of the above embodiment, wherein the housing is provided with an opening, and the cover plate is provided on the opening.

[0061] In the battery cell of this structure, the width of the step surface of the first step 211 on either side of the two ends of the rivet hole 21 in the length direction is smaller than the width of the step surface of the first step 211 on either side of the two ends of the rivet hole 21 in the width direction, and the minimum width b of the step surface of the first step 211 at both ends of the rivet hole 21 in the length direction and the width a of the step surface of the first step 211 at both ends of the rivet hole 21 in the width direction satisfy 0.5≤b / a≤0.8. In this way, compared with the same step surface width of the first step 211 at all circumferential locations, the distance between the side walls at both ends of the length direction of the column part 32 and the wall of the rivet hole 21 can be reduced before riveting, and the gap that needs to be filled between the two is reduced. After the column part 32 is riveted and expanded, the length direction of the column part 32 can be made The two ends of the column 32 are fitted on the inner wall of the rivet hole 21, which can ensure the fit between the two ends of the column 32 in the length direction and the side wall and the hole wall of the rivet block 2, and avoid the gap between the side walls at both ends of the length direction of the column 32 and the rivet block 2 being too large, which leads to a cold weld between the pole 3 and the rivet block 2, and can ensure the welding firmness between the column 32 and the rivet block 2, thereby improving the conductivity between the pole 3 and the rivet block 2, and improving the stability of the internal resistance of the battery cover; at the same time, 0.5≤b / a, which can prevent the step surface width of the first step 211 on both sides of the length direction and the width direction of the rivet hole 21 from being too different, and avoid serious material expansion on both sides of the length direction of the column 32, which causes the rivet block 2 to be squeezed and deformed.

[0062] In some optional embodiments, the battery cell includes a blade battery cell, the blade battery cell includes a shell, and the two ends of the shell are open in the length direction. The cover plate includes a positive cover plate and a negative cover plate, a positive electrode column 3 is provided on the positive cover plate, and a negative electrode column 3 is provided on the negative cover plate. The positive cover plate and the negative cover plate are respectively provided on the openings at both ends of the shell.

[0063] In other embodiments, the battery cell includes a prismatic battery cell, and the length of the cover body 1 of the prismatic battery cell is greater than its width.

[0064] According to another aspect of an embodiment of the present invention, a battery pack is provided, comprising the battery cell of the above embodiment.

[0065] In the battery pack of this structure, the width of the step surface of the first step 211 on either side of the rivet hole 21 in the length direction of the inner cell is smaller than the width of the step surface of the first step 211 on either side of the width direction of the rivet hole 21, and the minimum width b of the step surface of the first step 211 at both ends of the rivet hole 21 in the length direction and the width a of the step surface of the first step 211 at both ends of the rivet hole 21 in the width direction meet 0.5≤b / a≤0.8, which can ensure the fit between the two ends of the column part 32 in the length direction and the side wall and the hole wall of the rivet block 2, and avoid the column part The gap between the side walls at both ends of the length direction of 32 and the riveted block 2 is too large, resulting in a cold weld between the pole 3 and the riveted block 2, which can ensure the welding firmness between the column part 32 and the riveted block 2, thereby improving the conductivity between the pole 3 and the riveted block 2, and improving the stability of the internal resistance of the battery cover; at the same time, 0.5≤b / a, which can prevent the step surface width of the first step 211 on both sides of the length direction and the width direction of the riveted hole 21 from being too different, thereby avoiding serious material expansion on both sides of the length direction of the column part 32, which causes the riveted block 2 to be squeezed and deformed.

[0066] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A cover plate, characterized in that: include: The cover body is provided with a mounting hole; A rivet block having a rivet hole and disposed on the outer side of a surface of the cover plate body facing the outer side of the cover plate; the length of the rivet hole is greater than the width of the rivet hole; a first step is disposed on the inner wall of the rivet hole; the width of the step surface of the first step on either side of the two ends in the length direction of the rivet hole is less than the width of the step surface of the first step on either side of the two ends in the width direction of the rivet hole; the minimum width of the step surface of the first step at both ends in the length direction of the rivet hole is b, and the width of the step surface of the first step at both ends in the width direction of the rivet hole is a, 0.5≤b / a≤0.8, and the units of a and b are mm; The pole comprises a base plate and a column portion provided on the base plate, the column portion passes through the mounting hole and the rivet hole and is riveted to the rivet block, the base plate is located on the inner side of the other side surface of the cover body facing the inner side of the cover plate; the column portion extends in the same direction as the rivet block and the length of the column portion is greater than the width of the column portion, and the cross-sectional shape of the column portion is adapted to the shape of the rivet hole.

2. The cover plate according to claim 1, wherein: The rivet hole comprises a middle smooth area and arc-shaped areas at both ends of the middle smooth area, and the hole wall of the rivet hole at the middle smooth area transitions smoothly to the hole wall of the rivet hole at the arc-shaped areas.

3. The cover plate according to claim 2, wherein: The arc-shaped area is a semicircular arc, the middle smooth area is a rectangle, and the diameter of the semicircular arc is equal to the width of the middle smooth area; along the circumference of the semicircular arc, from the middle smooth area to the circumferential middle of the arc-shaped area, the width of the step surface of the first step gradually decreases; the cross-section of the column part is runway-shaped.

4. The cover plate according to any one of claims 1 to 3, characterized in that: 0.2mm≤a≤1.25mm.

5. The cover plate according to claim 4, characterized in that: 0.2mm≤b≤1mm.

6. The cover plate according to any one of claims 1 to 3, characterized in that: A pre-rivet groove is provided on a surface of the column portion facing the outer side of the cover plate, and the long side of the pre-rivet groove extends in the same direction as the long side of the column portion.

7. The cover plate according to any one of claims 1 to 3, characterized in that: A second step is provided on the inner wall of the rivet hole between the first step and the surface of the rivet block facing the outer side of the cover plate, and the width of the step surface of the second step is the same at all circumferential locations; the width of the step surface of the second step is c, and the height of the second step is h, 0.5mm≤c≤1.5mm, 0.2mm≤h≤0.5mm.

8. The cover plate according to any one of claims 1 to 3, characterized in that: The thickness between the step surface of the first step and the other side surface of the riveting block facing the inner side of the cover plate is t1, 0.5mm≤t1≤2mm; And / or, the total thickness of the riveting block is t, 1.5 mm≤t≤3.5 mm.

9. A battery cell, characterized in that: The invention comprises a shell and the cover plate according to any one of claims 1 to 8, wherein the shell is provided with an opening, and the cover plate is arranged on the opening.

10. A battery pack, characterized in that: Including the battery cell according to claim 9.

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