Battery cell cover plate assembly, battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell cover plate assembly, a battery cell and a battery pack. The battery cell cover plate assembly comprises a riveting block which is provided with a first through hole and a second through hole which are coaxially arranged, and a first step surface is formed at the joint of the first through hole and the second through hole; the pole partially penetrates through the first through hole and the second through hole and is attached to the hole walls of the first through hole and the second through hole; annular grooves extending in the circumferential direction of the pole are formed in the side wall of the pole, the groove wall of the annular groove located on the upper portion is attached to the first step face in the height direction of the pole, and the groove wall of the annular groove located on the lower portion is attached to the bottom face of the riveting block; the area of the cross section of the pole is S1, the area of the part, attached to the riveting block, of the pole is S2, and S1 and S2 meet the condition that S2 / S1 is larger than or equal to 1.3 and smaller than or equal to 2.0; the corresponding resistance value of the current flowing through the pole and the riveting block area is R, and the range of R is less than or equal to 0.035 m omega. According to the setting of S1, S2 and R, the overcurrent capability of the battery cell can be ensured, the internal resistance is reduced, and the heat productivity is reduced.

Description

Technical Field

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

[0002] In order to meet the fast charging needs of battery cells, multiple poles are usually set on the battery cell cover to increase the current flow area of ​​the poles and meet the battery cell's demand for large current transmission.

[0003] However, while the multiple-pole design improves the battery cell's high-current transmission capacity, it also increases the overall resistance of the cell cover. During the charge and discharge process, this increased resistance causes more electrical energy to be released as heat, raising the cell temperature and posing a threat to the safety of the cell. Summary of the Invention

[0004] In view of this, the present invention provides a battery cover assembly, a battery cell and a battery pack to solve the problem that the overall resistance of the existing battery cover is relatively high due to the provision of multiple poles, thereby causing the battery cell to have a higher temperature during the charging and discharging process.

[0005] In a first aspect, the present invention provides a battery cell cover assembly, comprising:

[0006] The riveting block is provided with a first through hole and a second through hole arranged coaxially, the size of the first through hole is larger than the size of the second through hole, and a first step surface is formed at the connection between the first through hole and the second through hole;

[0007] The pole is partially passed through the first through hole and the second through hole and is in contact with the hole walls of the first through hole and the second through hole; the side wall of the pole is provided with an annular groove extending along the circumference thereof, and along the height direction of the pole, the groove wall of the annular groove located above is in contact with the first step surface, and the groove wall of the annular groove located below is in contact with the bottom surface of the rivet block;

[0008] Along the height direction of the pole, the cross-sectional area of ​​the portion of the pole located below the bottom surface of the riveted block is S1, the area of ​​the contact portion between the pole and the riveted block is S2, and S1 and S2 satisfy the following: 1.3≤S2 / S1≤2.0; the corresponding resistance value of the current flowing through the pole and the riveted block area is R, and the range of R is: 0.010mΩ≤R≤0.035mΩ.

[0009] Beneficial effects: The present invention provides through holes of different sizes on the riveted block, and provides a first step surface at the connection of the through holes, which cooperates with the annular groove extending circumferentially on the side wall of the pole, so that the pole and the riveted block can be tightly fitted in multiple directions, so that the pole and the riveted block are tightly fitted, the connection stability of the pole and the riveted block is enhanced, and the energy loss during high current transmission is reduced. Secondly, the present invention controls the ratio of the fitting area S2 of the pole and the riveted block to the cross-sectional area S1 of the pole within the range of 1.3≤S2 / S1≤2.0, and controls the resistance R of the current flowing through this area within the range of 0.010mΩ≤R≤0.035mΩ, which can reduce the contact resistance between the pole and the riveted block, reduce the heat generated by the resistance during the charging and discharging process of the battery cell, and suppress the temperature rise of the battery cell. Furthermore, compared with the existing method of setting multiple poles and multiple rivet blocks on the battery cover, the present invention only sets one pole in the battery cover assembly, reducing the number of components and connection points on the battery cover assembly, reducing the problem of increased overall internal resistance caused by multiple rivet blocks, simplifying the manufacturing process and assembly process, and reducing errors and defective rates in the production process; at the same time, the design of a single pole can reduce production costs and space occupancy, and improve the energy density of the battery cell while meeting the high current transmission requirements of the battery cell.

[0010] In an optional embodiment, the cross-section of the pole is in the shape of an athletic track, and the cross-section of the pole includes a plane segment and arc segments located at both ends of the plane segment. The length of the cross-section of the pole is L, the width of the cross-section of the pole is W, and the cross-sectional area of ​​the pole is S1=Π×(W / 2) 2 +(LW)×W; L and W satisfy the following: 1.8≤L / W≤2.75.

[0011] Beneficial effects: The present invention designs the shape of the pole cross section to be in the shape of an athletic track, and limits the ratio of the length L of the pole cross section to the width W of the pole cross section to be within the range of 1.8≤L / W≤2.75, so that the pole can obtain a larger effective flow area in a limited space, and can carry a larger current than the traditional shape (cylindrical), which meets the fast charging requirements of the battery cell; at the same time, the shape of the athletic track optimizes the current distribution path, avoids the current from being concentrated in a local area, reduces the resistance increase and heating problems caused by uneven current density, and ensures that the temperature of the pole is stable during the charging and discharging process. In addition, the reasonable L / W ratio also enhances the adaptability of the pole and the annular groove of the riveted block, making the two fit more closely, effectively reducing the contact resistance, improving the conductive performance of the battery cover assembly, ensuring the safety and reliability of the battery cell under high current conditions, and extending the service life of the battery cell.

[0012] In an optional embodiment, the width of the portion where the groove wall of the annular groove located below and the bottom surface of the rivet block are in contact is a; the height of the portion where the pole is in contact with the inner wall of the second through hole is b; the width of the portion where the groove wall of the annular groove located above and the first step surface are in contact is c; the height of the portion where the pole is in contact with the inner wall of the first through hole is d; the area S2 of the portion where the pole is in contact with the rivet block is [Π×(W-2a)+2×(LW)]×b+{Π[W 2 / 4-(W / 2-a) 2 ]+(LW)×2a}+[Π×(W-2a+2c)+2×(LW)]×d+{Π[(W / 2-a+c) 2 -(W / 2-a) 2 ]+(LW)×2c]}.

[0013] Beneficial effect: The present invention decomposes the fitting area of ​​the pole and the riveted block into multiple parts for calculation. The introduction of parameters such as the fitting width (a, c) between the annular groove wall and the bottom surface of the riveted block, the first step surface, and the fitting height (b, d) between the pole and the inner wall of the through hole can make the fitting area calculation more accurate, thereby providing data support for the control of indicators such as conductive performance and mechanical strength in structural design.

[0014] In an optional embodiment, a, b, c and d satisfy: 0.3 mm ≤ a ≤ 0.8 mm, 1.3 mm ≤ b ≤ 1.5 mm, 0.2 mm ≤ c ≤ 0.5 mm, 1.0 mm ≤ d ≤ 1.5 mm, 2.3 mm ≤ b + d ≤ 3.0 mm.

[0015] Beneficial effect: The present invention limits the specific parameter ranges of a, b, c and d, and controls the range of b+d to between 2.3mm and 3.0mm. It can not only ensure that the pole and the riveted block form stable and close contact in the axial and radial directions, effectively increase the fitting area, reduce the contact resistance, and ensure that the resistance value of the current flowing through the area is 0.010mΩ≤R≤0.035mΩ, thereby reducing energy loss and heat generation during charging and discharging; it can also avoid assembly difficulties and material waste due to excessive parameters, or insufficient connection strength and decreased conductivity due to too small parameters.

[0016] In an optional embodiment, the length direction of the cross section of the pole is consistent with the length direction of the battery cell cover assembly, and the width direction of the cross section of the pole is consistent with the width direction of the battery cell cover assembly.

[0017] Beneficial effect: The present invention sets the length direction of the cross section of the pole to correspond to the length direction of the battery cover assembly, and sets the width direction of the cross section of the pole to correspond to the width direction of the battery cover assembly, which can fully utilize the spatial layout of the battery cover assembly and realize the reasonable arrangement of the poles.

[0018] In an optional embodiment, a pole base is provided at one end of the pole away from the riveted block, and the center of the pole is collinear with the center of the pole base; the center of the pole is collinear with the center of the riveted block.

[0019] Beneficial effect: In order to meet the welding requirements of the battery cell tabs, the eccentricity of the tabs cannot be large or small. Therefore, in a battery cell with a bipolar design, the portion of the pole base of one of the poles cannot usually be welded to the tabs. Therefore, it is necessary to increase the length of the pole base of the other pole to ensure the overcurrent capacity of the battery cell. However, the unused portion of the pole base and the extended portion of the pole base will lead to a decrease in material utilization and an increase in production costs. In addition, since the two poles need to be spaced a distance apart from each other in a battery cell with a bipolar design, the poles must be an eccentric structure relative to the pole base. Based on this, the present invention arranges the center of the pole and the center of the pole base in a collinear manner, which not only optimizes the current conduction path and avoids performance loss and structural hidden dangers caused by eccentricity, but also the single-pole design does not require an additional extension of the pole base, thereby improving material utilization and reducing production costs. While meeting the overcurrent capacity and tab welding requirements of the battery cell, the overall safety, reliability and economy of the battery cell are improved.

[0020] The present invention places the pole center and the riveted block center collinearly, ensuring assembly symmetry and stability. This avoids uneven stress on the pole and riveted block caused by eccentric installation, preventing loosening and deformation caused by stress concentration during high-current transmission, and improving connection reliability. Furthermore, the collinear design optimizes the current conduction path, allowing current to flow along the shortest straight line between the pole and the riveted block, reducing contact resistance and energy loss. It also keeps the resistance of the current-carrying area stable at a low level, suppressing temperature rise during charging and discharging.

[0021] In an optional embodiment, the riveting block is further provided with a welding hole coaxially arranged with the first through hole, the size of the welding hole is larger than the size of the first through hole, and a second step surface is formed at the connection between the welding hole and the first through hole.

[0022] Beneficial effects: The welding hole provides sufficient space for welding the pole and the riveted block, ensuring good contact between the pole and the riveted block during the welding process, helping to improve the sealing performance of the welding part, preventing electrolyte leakage, and ensuring the safety and reliability of the battery cell.

[0023] In a second aspect, the present invention further provides a battery cell, comprising:

[0024] The pole group has a pole ear at one end;

[0025] In the above-mentioned battery cell cover plate assembly, one end of the pole away from the rivet block is welded to the pole tab.

[0026] Beneficial effects: The battery cell of the present invention includes the battery cell cover assembly as described above, and has all the beneficial technical effects of the battery cell cover assembly, which will not be repeated here.

[0027] In an optional embodiment, a pole base is provided at one end of the pole away from the rivet block, the pole base is welded to the pole tab, and the length of the pole base is consistent with the length of the weld mark between the pole base and the pole tab.

[0028] Beneficial effects: The present invention keeps the length of the pole base consistent with the weld mark length between the pole base and the pole lug, which can avoid redundancy of pole base material, improve material utilization, and reduce production costs.

[0029] In a third aspect, the present invention further provides a battery pack comprising: a plurality of the above-mentioned battery cells.

[0030] Beneficial effects: The battery pack of the present invention includes the battery cell as described above and has all the beneficial technical effects of the battery cell, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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.

[0032] Figure 1 This is a structural schematic diagram of a battery cell cover assembly according to an embodiment of the present invention;

[0033] Figure 2 for Figure 1 The schematic diagram of the structure of the pole shown in FIG;

[0034] Figure 3 is a cross-sectional view of a pole and a riveted block in an assembled state according to an embodiment of the present invention;

[0035] Figure 4 is a cross-sectional view of the pole and the riveted block in an assembled state from another perspective of an embodiment of the present invention;

[0036] Figure 5 for Figure 1A cross-sectional view of the riveting block shown in ;

[0037] Figure 6 The figure is a schematic structural diagram of a battery cell according to an embodiment of the present invention.

[0038] Description of reference numerals:

[0039] 1. Riveting block; 101. First through hole; 102. Second through hole; 103. First step surface; 104. Welding hole; 105. Second step surface; 2. Pole; 201. Annular groove; 202. Plane segment; 203. Arc segment; 3. Pole base; 4. Pole group; 401. Pole ear; 5. Weld mark. DETAILED DESCRIPTION

[0040] 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.

[0041] In order to solve the problem that the overall resistance of the existing battery cell cover is relatively high due to the arrangement of multiple poles, which leads to high temperature of the battery cell during charging and discharging, the present invention provides a battery cell cover assembly, a battery cell and a battery pack.

[0042] The following combination Figures 1 to 6 , describing embodiments of the present invention.

[0043] According to an embodiment of the present invention, on the one hand, Figures 1 to 5 As shown, a battery cell cover assembly is provided, including: a riveted block 1 and a pole 2.

[0044] Specifically, the riveting block 1 is provided with a first through hole 101 and a second through hole 102 arranged coaxially. The size of the first through hole 101 is larger than that of the second through hole 102. A first step surface 103 is formed at the connection between the first through hole 101 and the second through hole 102; the pole 2 is partially inserted into the first through hole 101 and the second through hole 102 and fits in with the hole walls of the first through hole 101 and the second through hole 102; an annular groove 201 extending along its circumference is provided on the side wall of the pole 2. Along the height direction of the pole 2, the groove wall of the annular groove 201 located above fits in with the first step surface 103, and the groove wall of the annular groove 201 located below fits in with the bottom surface of the riveting block 1;

[0045] Along the height direction of the pole 2, the cross-sectional area of ​​the portion of the pole 2 located below the bottom surface of the riveted block 1 is S1, and the area of ​​the portion where the pole 2 and the riveted block 1 are in contact is S2. The relationship between S1 and S2 satisfies the following: 1.3≤S2 / S1≤2.0. The corresponding resistance value of the current flowing through the area between the pole 2 and the riveted block 1 is R, and the range of R is: 0.010mΩ≤R≤0.035mΩ.

[0046] The embodiment of the present invention provides through holes of different sizes on the riveted block 1 and provides a first stepped surface 103 at the connection of the through holes, which cooperates with the annular groove 201 extending circumferentially on the side wall of the pole 2 to achieve a multi-directional close fit between the pole 2 and the riveted block 1, so that the pole 2 and the riveted block 1 are closely fitted, enhancing the connection stability between the pole 2 and the riveted block 1 and reducing energy loss during high current transmission. Secondly, the embodiment of the present invention controls the ratio of the fitting area S2 of the pole 2 and the riveted block 1 to the cross-sectional area S1 of the pole 2 within the range of 1.3≤S2 / S1≤2.0, and controls the resistance R of the current flowing through this area within the range of 0.010mΩ≤R≤0.035mΩ, which can reduce the contact resistance between the pole 2 and the riveted block 1, reduce the heat generated by the resistance during the charging and discharging process of the battery cell, and suppress the temperature rise of the battery cell. Furthermore, compared with the existing method of setting multiple poles 2 and multiple rivet blocks 1 on the battery cover, the embodiment of the present invention only sets one pole 2 in the battery cover assembly, reducing the number of components and connection points on the battery cover assembly, reducing the problem of increased overall internal resistance caused by multiple rivet blocks 1, simplifying the manufacturing process and assembly process, and reducing errors and defective rates in the production process; at the same time, the design of a single pole 2 can reduce production costs and space occupancy, and improve the energy density of the battery cell while meeting the high current transmission requirements of the battery cell.

[0047] It can be understood that the cross section of the pole 2 in this embodiment refers to the cross section perpendicular to the height direction of the pole 2, that is, the flow cross section of the pole 2. Figure 1 It can be seen that, along the height direction of the pole 2, the portion of the pole 2 below the annular groove 201 is located outside the riveting block 1, and the size of this portion is larger than the size of the second through hole 102. Therefore, the cross-sectional area S1 of the pole 2 in this embodiment refers to the cross-sectional area corresponding to the cross section at the maximum size of the pole 2.

[0048] It should be noted that the ratio of S2 / S1 can be, but is not limited to, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0. The range of S1 is 30 mm. 2 ≤S1≤90mm 2 , the range of S2 is 58mm 2 ≤S2≤150mm 2 .

[0049] According to one embodiment of the present invention, Figures 2 to 4 As shown, the cross-section of the pole 2 is in the shape of an athletic track. The cross-section of the pole 2 includes a plane section 202 and arc sections 203 located at both ends of the plane section 202. The length of the cross-section of the pole 2 is L, the width of the cross-section of the pole 2 is W, and the cross-sectional area of ​​the pole 2 is S1 = Π × (W / 2) 2 +(LW)×W; L and W satisfy: 1.8≤L / W≤2.75. The embodiment of the present invention designs the shape of the cross section of the pole 2 to be in the shape of an athletic track, and limits the ratio of the cross-sectional length L of the pole 2 to the cross-sectional length W of the pole 2 to the range of 1.8≤L / W≤2.75, so that the pole 2 can obtain a larger effective flow area in a limited space, and can carry a larger current than the traditional shape (cylindrical), which meets the fast charging requirements of the battery cell; at the same time, the shape of the athletic track optimizes the current distribution path, avoids the current from being concentrated in a local area, reduces the resistance increase and heat generation problems caused by uneven current density, and ensures that the temperature of the pole 2 is stable during the charging and discharging process. In addition, the reasonable L / W ratio also enhances the adaptability of the pole 2 and the annular groove 201 of the riveted block 1, making the two fit more closely, effectively reducing the contact resistance, improving the conductive performance of the battery cover assembly, ensuring the safety and reliability of the battery cell under high current conditions, and extending the service life of the battery cell.

[0050] It should be noted that in this embodiment, the value range of L is: 8.5mm≤L≤15mm, and the value range of W in this embodiment is: 4.5mm≤W≤6mm. Secondly, the ratio of L / W can be, but is not limited to, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, or 2.75.

[0051] According to one embodiment of the present invention, Figure 3 and Figure 4 As shown, the width of the portion where the groove wall of the annular groove 201 located at the bottom and the bottom surface of the riveted block 1 are in contact is a; the height of the portion where the pole 2 and the inner wall of the second through hole 102 are in contact is b; the width of the portion where the groove wall of the annular groove 201 located at the top and the first step surface 103 are in contact is c; the height of the portion where the pole 2 and the inner wall of the first through hole 101 are in contact is d; the area S2 of the portion where the pole 2 and the riveted block 1 are in contact is [Π×(W-2a)+2×(LW)]×b+{Π[W 2 / 4-(W / 2-a) 2 ]+(LW)×2a}+[Π×(W-2a+2c)+2×(LW)]×d+{Π[(W / 2-a+c) 2 -(W / 2-a) 2]+(LW)×2c]}. This embodiment of the present invention breaks down the calculation of the area of ​​the contact portion between the pole 2 and the riveted block 1 into multiple parts. The introduction of parameters such as the contact widths (a, c) between the wall of the annular groove 201 and the bottom surface of the riveted block 1, the first step surface 103, and the contact heights (b, d) between the pole 2 and the inner wall of the through-hole make the contact area calculation more accurate, thereby providing data support for controlling indicators such as electrical conductivity and mechanical strength in structural design.

[0052] According to one embodiment of the present invention, a, b, c, and d satisfy the following: 0.3mm≤a≤0.8mm, 1.3mm≤b≤1.5mm, 0.2mm≤c≤0.5mm, 1.0mm≤d≤1.5mm, and 2.3mm≤b+d≤3.0mm. By limiting the specific parameter ranges of a, b, c, and d and controlling the range of b+d to between 2.3mm and 3.0mm, the embodiment of the present invention not only ensures that the pole 2 forms a stable and close contact with the riveted block 1 in both the axial and radial directions, effectively increases the fitting area, reduces the contact resistance, ensures that the resistance value of the current flowing through the area is 0.010mΩ≤R≤0.035mΩ, and reduces energy loss and heat generation during the charging and discharging process, but also avoids the problems of assembly difficulties and material waste caused by excessively large parameters, or insufficient connection strength and reduced conductivity caused by excessively small parameters.

[0053] It should be noted that a can be but not limited to 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.7mm, 0.8mm; b can be but not limited to 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm; c can be but not limited to 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm; d can be but not limited to 1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm.

[0054] According to one embodiment of the present invention, the length direction of the cross section of the pole 2 is consistent with the length direction of the battery cover assembly, and the width direction of the cross section of the pole 2 is consistent with the width direction of the battery cover assembly. In this embodiment of the present invention, the length direction of the cross section of the pole 2 is set corresponding to the length direction of the battery cover assembly, and the width direction of the cross section of the pole 2 is set corresponding to the width direction of the battery cover assembly, which can fully utilize the spatial layout of the battery cover assembly and realize the reasonable arrangement of the pole 2.

[0055] According to one embodiment of the present invention, Figures 2 to 4As shown, a pole base 3 is provided at one end of the pole 2 away from the riveted block 1, and the center of the pole 2 is arranged collinearly with the center of the pole base 3. In order to meet the welding requirements of the battery cell tabs, the eccentricity of the tabs cannot be large or small. Therefore, in a battery cell with a bipolar design, part of the pole base of one of the poles is usually unable to be welded to the tab, so it is necessary to increase the length of the pole base of the other pole to ensure the current capacity of the battery cell. However, the unused part of the pole base and the extended part of the pole base will lead to a decrease in material utilization and an increase in production costs. In addition, since the two poles need to be separated by a distance from each other in a battery cell with a bipolar design, the poles must be an eccentric structure relative to the pole base. Based on this, the embodiment of the present invention sets the center of the pole 2 and the center of the pole base 3 in the same line, which not only optimizes the current conduction path and avoids performance loss and structural hidden dangers caused by eccentricity, but also the single pole 2 design does not require additional lengthening of the pole base 3, thereby improving material utilization and reducing production costs. While meeting the battery cell's overcurrent capacity and the tab 401 welding requirements, it improves the overall safety, reliability and economy of the battery cell.

[0056] According to one embodiment of the present invention, Figures 2 to 4 As shown, the center of the pole 2 is collinear with the center of the riveted block 1. This embodiment of the present invention arranges the center of the pole 2 and the center of the riveted block 1 collinearly, ensuring the symmetry and stability of the assembly, avoiding uneven force on the pole 2 and the riveted block 1 due to eccentric installation, and preventing problems such as loosening and deformation due to stress concentration during high current transmission, thereby improving the reliability of the connection. Furthermore, the collinear design can optimize the current conduction path, allowing the current to pass through the area between the pole 2 and the riveted block 1 along the shortest straight line, reducing contact resistance and energy loss, and stably controlling the resistance value of the area where the current flows at a low level, thereby suppressing temperature rise during the charging and discharging process.

[0057] According to one embodiment of the present invention, Figures 3 to 5 As shown, the riveted block 1 is further provided with a welding hole 104 coaxially arranged with the first through hole 101. The size of the welding hole 104 is larger than that of the first through hole 101, and a second step surface 105 is formed at the connection between the welding hole 104 and the first through hole 101. It can be understood that the welding hole 104 provides sufficient space for welding the electrode 2 to the riveted block 1, ensuring good contact between the electrode 2 and the riveted block 1 during the welding process, helping to improve the sealing performance of the welding part, preventing electrolyte leakage, and ensuring the safety and reliability of the battery cell.

[0058] According to an embodiment of the present invention, on the other hand, Figure 6As shown, a battery cell is also provided, comprising: an electrode group 4 and the aforementioned battery cover assembly. Specifically, a terminal tab 401 is provided at one end of the electrode group 4; the end of the electrode post 2 in the aforementioned battery cover assembly, distal from the rivet block 1, is welded to the terminal tab 401. The battery cell of the present invention, including the aforementioned battery cover assembly, has all the beneficial technical effects of the battery cover assembly and will not be further elaborated here.

[0059] It should be noted that the battery cell in this embodiment can be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-hydrogen battery, a nickel-cadmium battery, a lead-acid battery, etc., and the embodiment of the present application is not limited to this.

[0060] In one embodiment, the electrode group 4 in this embodiment includes a plurality of alternating positive electrode sheets and negative electrode sheets and separators arranged between the positive electrode sheets and the negative electrode sheets.

[0061] Specifically, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector. For example, the positive electrode current collector has two surfaces opposing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two opposing surfaces of the positive electrode current collector. For example, the positive electrode current collector may be a metal foil, a metal foam, or a composite current collector. For example, the metal foil may include silver-treated aluminum or stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium. The metal foam may include nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam. The composite current collector may include a polymer base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy, etc.) on a polymer substrate (such as a substrate made of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0062] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector. For example, the negative electrode current collector has two surfaces opposing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the opposing surfaces of the negative electrode current collector. For example, the negative electrode current collector may be a metal foil, metal foam, or a composite current collector. For example, the metal foil may include silver-treated aluminum or stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium. The composite current collector may include a polymer base layer and a metal layer. The metal foam may include nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy, etc.) on a polymer substrate (such as a substrate made of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). For example, the negative electrode active material may be a negative electrode active material commonly known in the art for battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like.

[0063] In some embodiments, the separator is a separator. This application does not specifically limit the type of separator; any known porous separator with good chemical and mechanical stability can be used. For example, the separator can be made primarily of at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic.

[0064] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0065] It should be noted that the tabs 401 in this embodiment include positive and negative tabs. The positive tabs consist of the portion of the positive electrode sheet that does not contain active material, while the negative tabs consist of the portion of the negative electrode sheet that does not contain active material. The negative and positive tabs can be located together at one end of the electrode assembly 4 or separately at both ends of the electrode assembly 4.

[0066] According to one embodiment of the present invention, Figure 2 and Figure 6 As shown, a pole base 3 is provided at one end of the pole 2 away from the riveted block 1. The pole base 3 is welded to the pole tab 401. The length of the pole base 3 is consistent with the length of the weld mark 5 between the pole base 3 and the pole tab 401. In this embodiment of the present invention, the length of the pole base 3 is consistent with the length of the weld mark 5 between the pole base 3 and the pole tab 401, which can avoid material redundancy of the pole base 3, improve material utilization, and reduce production costs.

[0067] According to another aspect of an embodiment of the present invention, a battery pack is provided, comprising: a plurality of the above-mentioned battery cells. The battery pack of the embodiment of the present invention comprises the above-mentioned battery cells and has all the beneficial technical effects of the battery cells, which will not be described in detail here.

[0068] The effects of the embodiments of the present invention are described below in combination with some embodiments and comparative examples.

[0069] Table 1

[0070]

[0071]

[0072] It can be seen that when the following conditions are met: 1.8≤L / W≤2.75, 1.3≤S2 / S1≤2.0, the corresponding resistance R of the current flowing through the area of ​​pole 2 and riveted block 1 meets the design requirements. However, when the L / W ratio is too large, the riveting forming of pole 2 is irregular, and there is a tiny gap between pole 2 and riveted block 1, resulting in more welding points and excessive internal resistance of pole 2. When S2 / S1 is too small, the fitting area between pole 2 and riveted block 1 is insufficient, and the R value exceeds the upper limit by a large margin.

[0073] Table 2

[0074]

[0075] It can be seen that under the condition of ensuring the same cross-sectional area, the use of a track-and-field runway-shaped single-pole solution can significantly reduce the production cost of the battery cover assembly. At the same time, the internal resistance of the battery cover assembly under the single-pole solution is also significantly lower than that under the bipolar solution. Therefore, the overcurrent temperature rise of the battery cell can be reduced and the safety performance of the battery cell can be improved.

[0076] It should be noted that the Chinese meaning of “base” in the above text is “the price of a bipolar column cover plate in the prior art with the same cross-sectional area as that of the present application”.

[0077] 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 cover assembly, characterized in that: include: The riveting block is provided with a first through hole and a second through hole arranged coaxially, the size of the first through hole is larger than the size of the second through hole, and a first step surface is formed at the connection between the first through hole and the second through hole; The pole is partially passed through the first through hole and the second through hole and is in contact with the hole walls of the first through hole and the second through hole; the side wall of the pole is provided with an annular groove extending along the circumference thereof, and along the height direction of the pole, the groove wall of the annular groove located above is in contact with the first step surface, and the groove wall of the annular groove located below is in contact with the bottom surface of the rivet block; Along the height direction of the pole, the cross-sectional area of ​​the portion of the pole located below the bottom surface of the riveted block is S1, the area of ​​the contact portion between the pole and the riveted block is S2, and S1 and S2 satisfy the following: 1.3≤S2 / S1≤2.0; the corresponding resistance value of the current flowing through the pole and the riveted block area is R, and the range of R is: 0.010mΩ≤R≤0.035mΩ.

2. The battery cover assembly according to claim 1, characterized in that: The cross-section of the pole is in the shape of a track and field runway. The cross-section of the pole includes a plane segment and arc segments located at both ends of the plane segment. The length of the cross-section of the pole is L, the width of the cross-section of the pole is W, and the cross-sectional area of ​​the pole is S1 = Π × (W / 2) 2 +(LW)×W; L and W satisfy the following: 1.8≤L / W≤2.

75.

3. The battery cover assembly according to claim 2, characterized in that: The width of the portion where the groove wall of the annular groove located below and the bottom surface of the rivet block are in contact is a; the height of the portion where the pole and the inner wall of the second through hole are in contact is b; the width of the portion where the groove wall of the annular groove located above and the first step surface are in contact is c; the height of the portion where the pole and the inner wall of the first through hole are in contact is d; the area S2 of the portion where the pole and the rivet block are in contact is [Π×(W-2a)+2×(LW)]×b+{Π[W 2 / 4-(W / 2-a) 2 ]+(LW)×2a}+[Π×(W-2a+2c)+2×(LW)]×d+{Π[(W / 2-a+c) 2 -(W / 2-a) 2 ]+(LW)×2c]}.

4. The battery cover assembly according to claim 3, characterized in that: a, b, c and d satisfy: 0.3mm≤a≤0.8mm, 1.3mm≤b≤1.5mm, 0.2mm≤c≤0.5mm, 1.0mm≤d≤1.5mm, 2.3mm≤b+d≤3.0mm.

5. The battery cover assembly according to claim 2, characterized in that: The length direction of the cross section of the pole is consistent with the length direction of the cell cover assembly, and the width direction of the cross section of the pole is consistent with the width direction of the cell cover assembly.

6. The battery cell cover assembly according to any one of claims 1 to 5, characterized in that: A pole base is provided at one end of the pole away from the riveted block, the center of the pole is collinear with the center of the pole base, and the center of the pole is collinear with the center of the riveted block.

7. The battery cell cover assembly according to any one of claims 1 to 5, characterized in that: The rivet block is further provided with a welding hole coaxially arranged with the first through hole. The size of the welding hole is larger than that of the first through hole. A second step surface is formed at the connection between the welding hole and the first through hole.

8. A battery cell, characterized in that: include: The pole group has a pole ear at one end; The battery cell cover plate assembly according to any one of claims 1 to 7, wherein the end of the pole away from the rivet block is welded to the pole tab.

9. The battery cell according to claim 8, characterized in that A pole base is provided at one end of the pole away from the riveting block, and the pole base is welded to the pole tab. The length of the pole base is consistent with the length of the weld mark between the pole base and the pole tab.

10. A battery pack, characterized in that: include: A plurality of battery cells according to claim 9.

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