Battery cell and battery pack

Abstract

The present invention relates to the technical field of batteries, and discloses a battery cell and a battery pack, the battery cell comprises: a housing having an open end, the end face of the open end being a first end face; the cover plate comprises a cover plate body and a boss, the surface of the side, close to the shell, of the cover plate body is a first surface, the boss is formed by protruding a partial area on the first surface, the area, located between the edge of the cover plate body and the boss, on the first surface forms an abutting face, the abutting face abuts against the first end face, and the boss is located in the inner cavity of the shell; the size of the boss in the X direction is W1, the size of the boss in the Y direction is L1, the size of the inner cavity of the shell in the X direction is K1, the size of the inner cavity of the shell in the Y direction is B1, W1 is equal to K1, and L1 is equal to B1; the flatness of the abutting face is P1, the flatness of the first end face is P2, P1 is larger than 0 and smaller than 0.3 mm, and P2 is larger than 0 and smaller than 0.1 mm. And the welding yield is ensured by controlling the shape tolerance of the cover plate and the shell.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to battery cells and battery packs. Background Art

[0002] A battery cell generally includes a shell, electrode group, electrolyte, cover, internal and external insulation materials, etc. The cover and shell are usually fixed by laser welding to form a closed space with a certain structural strength to protect the electrode group. Due to the thin shell wall thickness and small size of the shell opening, coupled with the low positioning accuracy of the equipment when the cover is inserted into the shell, the shell cover welding yield in the assembly process is often low. The matching relationship between the cover and the shell is one of the key factors affecting its welding yield. The cover is located at the open end of the shell. If the cover and the shell do not match properly, there will be a gap when the cover and the shell are assembled, which will affect the shell cover welding yield and increase production costs. Summary of the Invention

[0003] In view of this, the present invention provides a battery cell and a battery pack to solve the problem of poor shell cover welding caused by improper fit between the cover plate and the shell.

[0004] In a first aspect, the present invention provides a battery cell, comprising: a shell having an open end, the end face of the open end being a first end face; a cover plate, comprising a cover plate body and a boss, the surface of the cover plate body on a side close to the shell being the first surface, the boss being formed by a protrusion of a partial area on the first surface, the area on the first surface between the edge of the cover plate body and the boss forming a contact surface, the contact surface contacting the first end face, the boss being located in an inner cavity of the shell; the dimension of the boss along the X direction is W1, the dimension of the boss along the Y direction is L1, the dimension of the inner cavity of the shell along the X direction is K1, and the dimension of the inner cavity of the shell along the Y direction is B1, wherein W1=K1, L1=B1; the flatness of the contact surface is P1, and the flatness of the first end face is P2, wherein 0<P1<0.3mm, 0<P2<0.1mm.

[0005] Beneficial effect: By setting the cover plate to include a cover plate body abutting on the end face of the open end of the shell and a boss extending into the inner cavity of the shell, and setting the dimension W1 of the boss along the X direction to be equal to the dimension K1 of the inner cavity of the shell along the X direction, and the dimension L1 of the boss along the Y direction to be equal to the dimension B1 of the inner cavity of the shell along the Y direction, the boss of the cover plate and the inner cavity of the shell are zero-matched, thereby improving the stability of the shell cover assembly, and at the same time, by setting the abutting surface on the cover plate body to abut the end face of the open end of the shell, and setting the flatness P1 of the abutting surface to be greater than 0 and less than 0.3mm, and the flatness P2 of the end face of the open end of the shell to be greater than 0 and less than 0.1mm, the shape tolerance of the cover plate and the shell is controlled, and the flatness of the abutting surface and the end face of the open end of the shell is ensured, thereby ensuring the fit between the abutting surface and the end face of the open end of the shell, ensuring good fit between the two, avoiding affecting the welding seal due to the gap between the two, thereby ensuring the welding yield of the cover plate and the shell, improving the production yield of the battery cell assembly process, and reducing costs.

[0006] In an optional embodiment, a perpendicularity H between the side wall of the shell and the first end face satisfies: 0<H<0.15mm.

[0007] Beneficial effect: On the basis that the flatness P2 of the end face of the open end of the shell is greater than 0 and less than 0.1mm, the verticality H between the side wall of the shell and the first end face is set to be greater than 0 and less than 0.15mm, thereby further controlling the shape tolerance of the shell, further ensuring a good fit between the shell and the cover plate, meeting the shell cover welding requirements, and improving the welding yield.

[0008] In an optional embodiment, the flatness P3 of the surface of the cover plate body on a side away from the boss satisfies: 0<P3<0.3mm.

[0009] Beneficial effects: further ensure that the entire cover has a smaller shape tolerance, improve the dimensional accuracy of the cover, avoid the second surface affecting the flatness of the first surface during processing, thereby ensuring the matching effect between the cover and the shell, ensuring welding quality, and improving welding yield.

[0010] In an optional embodiment, the size of the cover body along the X direction is W2, the size of the cover body along the Y direction is L2, the size of the outer contour of the shell along the X direction is K2, and the size of the outer contour of the shell along the Y direction is B2, wherein W2=K2, L2=B2.

[0011] Beneficial effect: By setting the dimension W2 of the cover body along the X direction to be equal to the dimension K2 of the outer contour of the shell along the X direction, and the dimension L2 of the cover body along the Y direction to be equal to the dimension B2 of the outer contour of the shell along the Y direction, after the cover is inserted into the shell, the outer peripheral surface of the cover body is flush with the outer peripheral surface of the shell, and the shell-cover joint position is flush with each other, which facilitates the laser welding and sealing of the cover and the shell along the joint position, is easy to operate, and is conducive to improving the welding quality, thereby improving the welding yield.

[0012] In an optional embodiment, the size W2 of the cover body along the X direction has a value range of 14 mm ≤ W2 ≤ 80 mm, and the size L2 of the cover body along the Y direction has a value range of 80 mm ≤ L2 ≤ 300 mm.

[0013] Beneficial effect: It can ensure that the battery cell has sufficient capacity and the overall strength of the battery cell, thereby improving the reliability of the battery cell.

[0014] In an optional embodiment, the total size of the cover plate along the Z direction is T0, and the size of the boss along the Z direction is T1, wherein 0.5≤T1 / T0≤0.7.

[0015] Beneficial effect: It can ensure that the cover plate and the shell have sufficient overlapping height, thereby ensuring the welding yield of the cover plate and the shell, and can also avoid the boss occupying too much space inside the shell, thereby increasing the capacity of the battery cell.

[0016] In an optional embodiment, the total dimension T0 of the cover plate along the Z direction has a value range of 1.5 mm ≤ T0 ≤ 2.5 mm; and / or the dimension T1 of the boss along the Z direction has a value range of 0.75 mm ≤ T1 ≤ 1.75 mm.

[0017] Beneficial effect: By setting the total dimension T0 of the cover plate along the Z direction to be within the range of 1.5 mm to 2.5 mm, it is possible to ensure that the cover plate has sufficient strength, improve reliability, ensure that the cover plate and the shell have a sufficient overlap height, thereby ensuring the welding yield of the cover plate and the shell, and avoid excessive weight of the cover plate, control costs, and at the same time avoid the boss from occupying too much space inside the shell, thereby increasing the capacity of the battery cell;

[0018] By setting the dimension T1 of the boss along the Z direction to be in the range of 0.75mm to 1.75mm, it can be ensured that the cover and the shell have sufficient overlap height, thereby ensuring the welding yield of the cover and the shell, and the boss can be avoided from occupying too much space inside the shell, thereby increasing the battery cell capacity.

[0019] In an optional embodiment, the thickness t of the side wall of the shell is in the range of 0.3 mm ≤ t ≤ 0.8 mm.

[0020] Beneficial effects: It can ensure that the shell has sufficient strength, ensure that the flatness P2 of the end face of the shell opening end and the verticality H between the side wall of the shell and the first end face can meet the design requirements, and avoid the problem of bulging of the large surface of the shell during the shell molding process due to the shell being too thick, thereby ensuring the welding quality of the shell and the cover plate and ensuring the welding yield.

[0021] In an optional embodiment, the edge of the boss away from the cover body is configured as a chamfer, and the size of the chamfer is in the range of 0.3 mm to 0.5 mm.

[0022] Beneficial effect: By designing a chamfered structure at the edge of the side of the boss away from the cover body, it plays a certain guiding role in the process of the cover entering the shell, and by setting the chamfer size to be in the range of 0.3mm to 0.5mm, it avoids the poor guiding effect caused by the chamfer size being too small or too large, thereby facilitating the assembly of the cover and the shell.

[0023] In a second aspect, the present invention further provides a battery pack comprising the above-mentioned battery cell. Since the battery pack comprises the battery cell and has the same effects as the battery cell, details thereof will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] Figure 1 This is a schematic structural diagram of a battery cell according to an embodiment of the present invention;

[0026] Figure 2 for Figure 1 A partial enlarged schematic diagram of D in the middle;

[0027] Figure 3 for Figure 1 Schematic diagram of the positional relationship between the battery cell housing and the cover before assembly;

[0028] Figure 4 for Figure 3 A partial enlarged schematic diagram of E in the middle;

[0029] Figure 5 is a partial enlarged schematic diagram of a housing near its opening end according to an embodiment of the present invention;

[0030] Figure 6This is a schematic structural diagram of a cover plate according to an embodiment of the present invention from a first perspective;

[0031] Figure 7 A schematic structural diagram of a cover plate according to a second perspective of an embodiment of the present invention;

[0032] Figure 8 for Figure 7 A partial enlarged schematic diagram of F in the middle;

[0033] Figure 9 It is a schematic diagram of the structure of a traditional square shell battery cell;

[0034] Figure 10 for Figure 9 A partial enlarged schematic diagram of G in the middle.

[0035] Description of reference numerals:

[0036] 1. Shell; 101. First end face; 2. Cover plate; 201. Cover plate body; 202. Boss; 203. Abutment surface; 301. First weld mark position; 302. Second weld mark position. DETAILED DESCRIPTION

[0037] 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.

[0038] The shell 1 and cover 2 of the battery cell are usually fixedly connected by laser welding. Traditional square shell batteries generally use top welding. The structural diagram of the square shell battery cell is shown in the figure. Figures 9 and 10 As shown, the joint position of the cover plate 2 and the shell 1 is located at the upper end of the entire battery cell, that is, Figure 10 The second welding position 302 shown in FIG, the cover plate 2 and the shell 1 of the square shell battery cell are welded along the second welding position 302, wherein the upper end refers to Figures 9 and 10 The end in the direction of "up" pointed by the middle arrow; long cells are generally fixed by side welding. The structural diagram of long cells is as follows Figure 1 As shown, the combination position of the cover plate 2 and the shell 1 is located on the side of the battery cell, that is, Figure 2The first weld mark 301 is shown in the figure. During the welding process of the cover plate 2 and the housing 1 of the long battery cell, the welding is carried out along the first weld mark 301. For prismatic battery cells, the housing cover fits relatively easily due to the larger opening of the housing 1. However, for long battery cells, the thin wall thickness, small opening, and long length of the housing 1 make dimensional control more difficult. Furthermore, the relatively low positioning accuracy of the equipment when the cover plate 2 is inserted into the housing leads to a low yield rate for the housing cover welding during the assembly process, affecting production efficiency.

[0039] The following combination Figures 1 to 8 , describing embodiments of the present invention.

[0040] According to an embodiment of the present invention, on one hand, a battery cell is provided, including: a housing 1 and a cover plate 2 . The shell 1 has an open end, and the end face of the open end is the first end face 101; the cover 2 includes a cover body 201 and a boss 202, the surface of the cover body 201 on the side close to the shell 1 is the first surface, the boss 202 is formed by a partial area on the first surface, and the area on the first surface between the edge of the cover body 201 and the boss 202 forms a contact surface 203, the contact surface 203 contacts the first end face 101, and the boss 202 is located in the inner cavity of the shell 1; the size of the boss 202 along the X direction is W1, the size of the boss 202 along the Y direction is L1, the size of the inner cavity of the shell 1 along the X direction is K1, and the size of the inner cavity of the shell 1 along the Y direction is B1, wherein W1=K1, L1=B1; the flatness of the contact surface is P1, and the flatness of the first end face 101 is P2, wherein 0<P1<0.3mm, 0<P2<0.1mm. wherein the X direction and the Y direction respectively refer to Figures 1 to 6 In the XYZ rectangular coordinate system, the X-axis and Y-axis are perpendicular to each other, the plane containing the large surface of cover plate 2 is parallel to the XY plane, and the end surface of the open end of housing 1 is parallel to the XY plane. The Z-axis in the rectangular coordinate system is perpendicular to the plane containing the large surface of cover plate 2. The longest side of housing 1 is parallel to the Z-axis, the first end surface 101 is located at the end of housing 1 along the Z-direction, and cover plate 2 is disposed at the end of housing 1 along the Z-direction. Boss 202 is formed by a portion of the first surface of cover plate body 201 on the side closest to housing 1, extending along the Z-axis toward the inner cavity of housing 1. Boss 202 is located in the middle of the first surface, so the abutment surface 203 formed by the area of the first surface excluding boss 202 is annular and connected to the outer periphery of boss 202.

[0041] In the battery cell of this embodiment, the cover plate 2 is provided to include a cover plate body 201 abutting against the end face of the open end of the shell 1 and a boss 202 extending into the inner cavity of the shell 1, and the dimension W1 of the boss 202 along the X direction is equal to the dimension K1 of the inner cavity of the shell 1 along the X direction, and the dimension L1 of the boss 202 along the Y direction is equal to the dimension B1 of the inner cavity of the shell 1 along the Y direction, so that the boss 202 of the cover plate 2 is zero-matched with the inner cavity of the shell 1, thereby improving the stability of the shell cover assembly. At the same time, by providing an abutting surface 203 on the cover plate body 201 to abut against the end face of the open end of the shell 1, The cover plate 2 and the shell 1 are connected, and the flatness P1 of the abutting surface 203 is set to be greater than 0 and less than 0.3 mm, and the flatness P2 of the end face of the open end of the shell 1 is set to be greater than 0 and less than 0.1 mm. The shape tolerances of the cover plate 2 and the shell 1 are controlled to ensure the flatness of the abutting surface 203 and the end face of the open end of the shell 1, thereby ensuring the fit between the abutting surface 203 and the end face of the open end of the shell 1, ensuring good cooperation between the two, avoiding affecting the welding seal due to the gap between the two, improving the welding quality, thereby ensuring the welding yield of the cover plate 2 and the shell 1, improving the production yield of the battery cell assembly process, and reducing costs.

[0042] It should be noted that flatness refers to the deviation of the macroscopic concave and convex height of the substrate from the ideal plane. It is an indicator that limits the variation of the actual plane from its ideal plane. It is used to control the shape error of the actual plane being measured. Flatness is one of the shape tolerances. It should be noted that in actual measurement, due to manufacturing and measurement errors, it is difficult to achieve a perfect plane state, so the flatness cannot be completely equal to 0. On the basis of flatness being greater than 0, the lower the flatness value of the base surface, the better the flatness of the base surface. When it abuts against another base surface, the better the fit between the two base surfaces, the smaller the gap, and the better the sealing. Specifically, if P1 is greater than or equal to 0.3 mm, the flatness of the abutting surface 203 is too large, and the flatness of the abutting surface 203 is poor; or if P2 is greater than or equal to 0.1 mm, the flatness of the end face of the open end of the shell 1 and the flatness of the end face of the open end of the shell 1 are poor, which will result in a low degree of fit between the abutting surface 203 and the end face of the open end of the shell 1, and a good fit cannot be achieved. The gap between the two affects the welding seal, and the welding quality is poor.

[0043] In one embodiment, the perpendicularity between the side wall of the shell 1 and the first end face 101 is H, where 0<H<0.15mm. It should be noted that the side wall of the shell 1 includes a first side wall, a second side wall, a third side wall and a fourth side wall connected end to end, the first side wall and the third side wall are arranged opposite to each other and are parallel to the XZ plane in the rectangular coordinate system, and the second side wall and the fourth side wall are arranged opposite to each other and are parallel to the YZ plane in the rectangular coordinate system; the perpendicularity between the side wall of the shell 1 and the first end face 101 refers to the perpendicularity between any one of the four side walls of the shell 1 and the first end face 101; the perpendicularity is the tolerance requirement in the directional tolerance to control the angle between the measured element (i.e., the first end face 101) and the reference element (i.e., the side wall of the shell 1) to be 90°. It should be noted that in actual measurement, due to manufacturing and measurement errors, it is difficult to achieve perfect Vertical state, so the verticality cannot be completely equal to 0. On the basis of the verticality being greater than 0, the smaller the value of the verticality, the better the vertical state between the first end face 101 and the side wall of the shell 1. If H is greater than 0.15mm, the vertical state between the first end face 101 and the side wall of the shell 1 is too poor, affecting the welding quality between the shell 1 and the cover plate 2. On the basis of the flatness P2 of the end face of the open end of the shell 1 being greater than 0 and less than 0.1mm, the verticality H between the side wall of the shell 1 and the first end face 101 is set to be greater than 0 and less than 0.15mm, further controlling the shape tolerance of the shell 1, further ensuring a good fit between the shell 1 and the cover plate 2, meeting the shell cover welding requirements, and improving the welding yield.

[0044] Preferably, the perpendicularity between the outer peripheral surface of the boss 202 and the abutting surface 203 is less than 0.15 mm, further ensuring a smaller fitting tolerance between the cover plate 2 and the shell 1, reducing the assembly gap between the cover plate 2 and the shell 1, and improving the welding yield.

[0045] In one embodiment, the flatness of the surface of the cover plate body 201 away from the boss 202 is P3, where 0 < P3 < 0.3 mm. It should be noted that the surface of the cover plate body 201 away from the boss 202 is arranged opposite to the first surface of the cover plate body 201 and is the second surface, which is also the surface of the cover plate body 201 facing the outside of the housing 1. If P3 is greater than 0.3 mm, the flatness of the surface of the cover plate body 201 away from the boss 202 is too large, the flatness is poor, and the dimensional accuracy of the cover plate 2 is poor. This will affect the flatness of the first surface during processing, and further affect the welding quality of the cover plate 2 and the housing 1. By setting the flatness of the second surface P3 to be greater than 0 and less than 0.3 mm, the entire cover plate 2 is further ensured to have a smaller shape tolerance, improve the dimensional accuracy of the cover plate 2, and prevent the second surface from affecting the flatness of the first surface during processing, thereby ensuring the fit between the cover plate 2 and the housing 1, ensuring welding quality, and improving the welding yield rate. It should be noted that the second surface faces the outside of the shell 1, and the surface area of the second surface is larger than the surface area of the abutment surface 203 on the first surface. The flatness of the entire cover 2 is less than 0.3 mm. During the inspection process, it is only necessary to inspect the flatness P3 of the second surface, which is convenient for operation.

[0046] In one embodiment, further combined Figure 5 and Figure 6 As shown, the dimension of the cover body 201 along the X direction is W2, the dimension of the cover body 201 along the Y direction is L2, the dimension of the outer contour of the shell 1 along the X direction is K2, and the dimension of the outer contour of the shell 1 along the Y direction is B2, wherein W2=K2, L2=B2. The outer contour of the shell 1 refers to the contour of the side of the shell 1 that is away from the center of the projection on the cross section parallel to the XY plane. By setting the dimension W2 of the cover body 201 along the X direction equal to the dimension K2 of the outer contour of the shell 1 along the X direction, and the dimension L2 of the cover body 201 along the Y direction equal to the dimension B2 of the outer contour of the shell 1 along the Y direction, after the cover 2 is inserted into the shell, the outer peripheral surface of the cover body 201 is flush with the outer peripheral surface of the shell 1, and the shell cover joint position is flush with each other, which facilitates the laser welding and sealing of the cover 2 and the shell 1 along the joint position, which is convenient to operate and helps to improve the welding quality, thereby improving the welding yield.

[0047] In one embodiment, the dimension W2 of the cover body 201 along the X direction is in the range of 14mm≤W2≤80mm, and the dimension L2 of the cover body 201 along the Y direction is in the range of 80mm≤L2≤300mm. It should be noted that if the dimension W2 of the cover body 201 along the X direction is less than 14mm or the dimension L2 of the cover body 201 along the Y direction is less than 80mm, the size of the cover 2 is too small, and correspondingly, the size of the shell 1 along the X direction or the Y direction is too small, and the space provided by the shell 1 for the electrode group is too small, resulting in insufficient battery cell capacity; if the dimension W2 of the cover body 201 along the X direction is greater than 80mm or the dimension L2 of the cover body 201 along the Y direction is greater than 300mm, the size of the cover 2 is too large, and correspondingly, the size of the shell 1 along the X direction or the Y direction is too large, and the strength of the shell 1 is insufficient. Therefore, by setting the dimension W2 of the cover body 201 along the X direction to be in the range of 14mm to 80mm, and the dimension L2 of the cover body 201 along the Y direction to be in the range of 80mm to 300mm, it is possible to ensure that the battery cell has sufficient capacity and the overall strength of the battery cell can be ensured, thereby improving the reliability of the battery cell.

[0048] It should be noted that the dimension K2 of the outer contour of the shell 1 along the X direction is equal to the dimension W2 of the cover body 201 along the X direction, and the value range of K2 is: 14mm≤K2≤80mm; the dimension B2 of the outer contour of the shell 1 along the Y direction is equal to the dimension L2 of the cover body 201 along the Y direction, and the value range of B2 is: 80mm≤B2≤300mm.

[0049] In one embodiment, further combined Figure 5As shown, the range of the thickness t of the side wall of the shell 1 is: 0.3mm≤t≤0.8mm. It should be noted that if the thickness t of the side wall of the shell 1 is less than 0.3mm, the shell 1 is too thin, the shell 1 is weak, and it is easy to deform. In the production process of the shell 1, it is difficult to ensure that the flatness P2 of the end face of the open end of the shell 1 and the verticality H between the side wall of the shell 1 and the first end face 101 meet the requirements of P2<0.1mm and H<0.15mm, which will affect the welding yield of the cover plate 2 and the shell 1; if the thickness t of the side wall of the shell 1 is greater than 0.8mm, the shell 1 is too thick, and the corner where the two adjacent side walls are connected is difficult to bend during the processing and forming of the shell 1. The inner R angle of the corner is uneven, which will also cause the large surface of the shell 1 to bulge outward, affecting the welding yield with the cover plate 2. Therefore, by setting the wall thickness t of the side wall of the shell 1 to a value within the range of 0.3 mm to 0.8 mm, it can be ensured that the shell 1 has sufficient strength and that the flatness P2 of the end face of the open end of the shell 1 and the verticality H between the side wall of the shell 1 and the first end face 101 can meet the design requirements. It can also avoid the problem of bulging of the large surface of the shell 1 during the shell 1 molding process due to the shell 1 being too thick, thereby ensuring the welding quality of the shell 1 and the cover plate 2 and the welding yield.

[0050] Preferably, the housing 1 is made of aluminum, which is lightweight, easily available, and low in cost.

[0051] It should be noted that the dimension of the inner cavity of the shell 1 along the X direction is K1=K2-2t, and the dimension of the inner cavity of the shell 1 along the Y direction is B1=B2-2t; the abutting surface 203 on the cover plate 2 is annular, and the abutting surface 203 is arranged opposite to the first end face 101. The ring width of the annular ring is equal to the wall thickness t of the side wall of the shell 1, then the dimension of the boss 202 along the X direction is W1=W2-2t; the dimension of the boss 202 along the Y direction is L1=L2-2t.

[0052] In one embodiment, further combined Figure 4As shown, the total dimension of the cover plate 2 along the Z direction is T0, and the dimension of the boss 202 along the Z direction is T1, wherein 0.5≤T1 / T0≤0.7. It should be noted that the Z direction refers to the direction of the Z axis in the rectangular coordinate system. The total dimension T0 of the cover plate 2 along the Z direction is the total thickness of the cover plate 2, and the dimension T1 of the boss 202 along the Z direction is the thickness of the boss 202. If T1 / T0 is less than 0.5, the thickness of the boss 202 is relatively too small. After the cover plate 2 and the shell 1 are assembled, the overlap height of the cover plate 2 extending into the inner cavity of the shell 1 for overlap is insufficient, and the weld seal yield rate of the cover plate 2 and the shell 1 is low. If T1 / T0 is greater than 0.7, the thickness of the boss 202 is relatively too large, occupying too much internal space of the battery cell, affecting the battery cell capacity. Therefore, by setting the ratio T1 / T0 between the thickness T1 of the boss 202 and the total thickness T0 of the cover plate 2 to be in the range of 0.5 to 0.7, it can be ensured that the cover plate 2 and the shell 1 have sufficient overlap height, thereby ensuring the welding yield of the cover plate 2 and the shell 1, and it can also avoid the boss 202 occupying too much space inside the shell 1, thereby improving the battery cell capacity.

[0053] In one embodiment, the total dimension T0 of the cover plate 2 along the Z direction has a value range of 1.5mm≤T0≤2.5mm. If the total thickness T0 of the cover plate 2 is less than 1.5mm, the total thickness of the cover plate 2 is too small, the overall strength of the cover plate 2 is insufficient, and the reliability is poor. Correspondingly, the thickness of the boss 202 is too small, the overlap height of the cover plate 2 extending into the inner cavity of the shell 1 is insufficient, and the weld sealing yield rate of the cover plate 2 and the shell 1 is low. If the total thickness of the cover plate 2 is greater than 2.5mm, the total thickness of the cover plate 2 is too large, the overall weight is large, the cost is high, and correspondingly, the thickness of the boss 202 is too large, occupying too much internal space of the battery cell, affecting the battery cell capacity. Therefore, by setting the total dimension T0 of the cover plate 2 along the Z direction to be in the range of 1.5mm to 2.5mm, it can be ensured that the cover plate 2 has sufficient strength, improve reliability, ensure that the cover plate 2 and the shell 1 have sufficient overlap height, thereby ensuring the welding yield of the cover plate 2 and the shell 1, and avoid the cover plate 2 from being too heavy, control costs, and at the same time avoid the boss 202 occupying too much space inside the shell 1, thereby improving the battery cell capacity.

[0054] In one embodiment, the dimension T1 of the boss 202 along the Z direction has a value range of: 0.75mm≤T1≤1.75mm. If the dimension T1 of the boss 202 along the Z direction is less than 0.75mm, the thickness of the boss 202 is relatively too small. After the cover plate 2 and the shell 1 are assembled, the overlap height of the cover plate 2 extending into the inner cavity of the shell 1 for overlap is insufficient, and the weld seal yield rate of the cover plate 2 and the shell 1 is low. If the dimension T1 of the boss 202 along the Z direction is greater than 1.75mm, the thickness of the boss 202 is relatively too large, occupying too much internal space of the battery cell, affecting the battery cell capacity. Therefore, by setting the dimension T1 of the boss 202 along the Z direction to a value within the range of 0.75mm to 1.75mm, it is possible to ensure that the cover plate 2 and the shell 1 have sufficient overlap height, thereby ensuring the welding yield rate of the cover plate 2 and the shell 1, and to avoid the boss 202 occupying too much space inside the shell 1, thereby increasing the battery cell capacity.

[0055] In one embodiment, the edge of the boss 202 away from the cover body 201 is chamfered, with the chamfer dimension ranging from 0.3mm to 0.5mm. The side of the boss 202 away from the cover body 201 extends into the interior of the housing 1. The chamfered edge of the boss 202 away from the cover body 201 provides a guide for the cover 2 during insertion into the housing. Furthermore, by setting the chamfer dimension within the range of 0.3mm to 0.5mm, the chamfer dimension, which is too small or too large, can be avoided, thereby facilitating assembly of the cover 2 and the housing 1.

[0056] Experimental tests were conducted on shells and cover plates with different flatness and verticality to verify the influence of the fit between the cover plate 2 and the shell 1 with different flatness and verticality on the shell-cover welding results.

[0057] Table 1 The influence of shell cover fitting with different flatness and verticality on the shell cover welding results

[0058]

[0059] Taking Implementation Case 1 as an example, Implementation Case 1 refers to taking a number of cover plates 2 processed according to the requirement that the flatness P1 of the abutment surface 203 is between 0.20mm and 0.30mm (including 0.20mm and excluding 0.30mm), and the same number of shells 1 processed according to the requirement that the flatness P2 of the end face of the open end of the shell 1 is less than 0.10mm and the verticality H between the side wall of the shell 1 and the first end face 101 is less than 0.15mm, assembling the cover plates 2 and the shell 1 into battery cells, and calculating the welding yield rate after welding the cover plates 2 and the shell 1, wherein the welding yield rate is the percentage of battery cells with qualified welding in this group of implementation cases to the total number of battery cells in this group of implementation cases. The same is true for other implementation cases and comparative cases, and the number of cover plates 2 and shells 1 taken in different implementation cases or comparative cases is equal.

[0060] As can be seen from Table 1, for implementation cases 1 to 3, the flatness P1 of the abutting surface 203 of the cover plate 2 is less than 0.3 mm, the flatness P2 of the end surface of the open end of the shell 1 is less than 0.1 mm, and the verticality H between the side wall of the shell 1 and the first end surface 101 is less than 0.15 mm, that is, the flatness and verticality are within the range specified in this application, and the shell cover welding yield can reach 99.12%, 99.31%, and 99.08%, respectively, all above 99%, with a high welding yield that meets production requirements; however, for comparative cases 1 and 2, the flatness P1 of the abutting surface 203 is greater than 0.3 mm, which is not within the range specified in this application, and the cover plate 2 is too flat, and the shell cover welding yield is only 97.23% and 96.72% respectively, which is low; for comparative case 3 and comparative case 4, the flatness P2 of the end face of the open end of the shell 1 is greater than 0.1mm, which is not within the range specified in this application, the shell mouth flatness is too large, and the shell cover welding yield is only 97.13% and 96.87%, which is low; for comparative case 5 and comparative case 6, the verticality H between the side wall of the shell 1 and the first end face 101 is greater than 0.15mm, which is not within the range specified in this application, the shell verticality is too large, and the shell cover welding yield is only 96.63% and 97.21% respectively, which is low.

[0061] In summary, when the flatness P1 of the abutting surface 203 is greater than 0 and less than 0.3 mm, the flatness P2 of the end face of the open end of the shell 1 is greater than 0 and less than 0.1 mm, and the verticality H between the side wall of the shell 1 and the first end face 101 is greater than 0 and less than 0.15 mm, by controlling the shape tolerance, the fit between the abutting surface 203 and the end face of the open end of the shell 1 can be guaranteed, and good cooperation between the two can be guaranteed, thereby ensuring the welding yield of the cover plate 2 and the shell 1, improving the production yield of the battery cell assembly process, and reducing costs.

[0062] In addition, by comparing Implementation Case 1 with Implementation Case 2, it can be seen that the flatness P1 of the abutment surface 203 in Implementation Case 2 is smaller, and by comparing Implementation Case 1 with Implementation Case 3, it can be seen that the verticality H in Implementation Case 3 is smaller. As a result, the production yields of the shell and cover in Implementation Case 1 are normal, and the cost is not affected. The production yield of the cover in Implementation Case 2 is slightly lower (but meets the production requirements), and the production yield of the shell in Implementation Case 3 is slightly lower (but meets the production requirements). It can be seen that the stricter the control of flatness and verticality, the lower the production yield of the cover 2 and the shell 1 will be, and the cost will increase slightly.

[0063] It should be noted that in order to improve the accuracy of the test results, multiple sampling tests can be carried out for the same experimental conditions. Specifically, for the experimental conditions of Implementation Case 1, this experiment conducted three sampling tests, and the shell cover welding yields reached 99.28%, 99.12%, and 99.30% respectively, and the lowest one also reached 99.12%; for the experimental conditions of Implementation Case 3, this experiment conducted two sampling tests, and the shell cover welding yields reached 99.22% and 99.08% respectively, and the lowest one also reached 99.08%.

[0064] The battery cell of this embodiment reasonably sets the dimensions and tolerances of the shell 1 and the cover plate 2, controls the flatness P1 of the abutting surface 203 on the cover plate 2 abutting against the end face of the shell 1 to satisfy 0<P1<0.3mm, the flatness P2 of the end face of the open end of the shell 1 to satisfy 0<P2<0.1mm, and the verticality H between the side wall of the shell 1 and the end face of the open end of the shell 1 to satisfy 0<H<0.15mm, thereby ensuring the production yield of each of the shell 1 and the cover plate 2, and at the same time meeting the welding requirements of the cover plate 2 and the shell 1, ensuring the shell-cover welding yield of >99.0%, improving the production yield of the battery cell assembly stage, and reducing costs.

[0065] According to another aspect of an embodiment of the present invention, a battery pack is provided, comprising: the above-mentioned battery cell. Preferably, there are multiple battery cells.

[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 battery cell, characterized in that: include: The shell has an open end, wherein the end surface of the open end is a first end surface; The cover plate includes a cover plate body and a boss, wherein a surface of the cover plate body on a side close to the shell is a first surface, the boss is formed by a raised portion of the first surface, an area on the first surface between an edge of the cover plate body and the boss forms an abutment surface, the abutment surface abuts against the first end surface, and the boss is located in the inner cavity of the shell; The size of the boss along the X direction is W1, the size of the boss along the Y direction is L1, the size of the inner cavity of the shell along the X direction is K1, and the size of the inner cavity of the shell along the Y direction is B1, wherein W1=K1, L1=B1; the flatness of the abutting surface is P1, and the flatness of the first end surface is P2, wherein 0<P1<0.3mm, 0<P2<0.1mm.

2. The battery cell according to claim 1, characterized in that The verticality between the side wall of the shell and the first end surface is H, wherein 0<H<0.15mm.

3. The battery cell according to claim 1, characterized in that The flatness of the surface of the cover body on a side away from the boss is P3, wherein 0<P3<0.3mm.

4. The battery cell according to claim 1, characterized in that The size of the cover body along the X direction is W2, the size of the cover body along the Y direction is L2, the size of the outer contour of the shell along the X direction is K2, and the size of the outer contour of the shell along the Y direction is B2, wherein W2=K2, L2=B2.

5. The battery cell according to claim 4, characterized in that: The value range of the dimension W2 of the cover body along the X direction is: 14mm≤W2≤80mm, and the value range of the dimension L2 of the cover body along the Y direction is: 80mm≤L2≤300mm.

6. The battery cell according to claim 1, characterized in that The total size of the cover plate along the Z direction is T0, and the size of the boss along the Z direction is T1, wherein 0.5≤T1 / T0≤0.

7.

7. The battery cell according to claim 6, characterized in that The total dimension T0 of the cover plate along the Z direction is in the range of 1.5 mm ≤ T0 ≤ 2.5 mm; And / or, the dimension T1 of the boss along the Z direction has a value range of: 0.75 mm ≤ T1 ≤ 1.75 mm.

8. The battery cell according to claim 1, characterized in that The thickness t of the side wall of the shell has a value range of 0.3 mm ≤ t ≤ 0.8 mm.

9. The battery cell according to any one of claims 1 to 8, characterized in that: The edge of the boss away from the cover body is configured as a chamfer, and the size of the chamfer is in the range of 0.3 mm to 0.5 mm.

10. A battery pack, characterized in that: include: The battery cell according to any one of claims 1 to 9.

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