Pole structure, cover plate assembly and battery cell

Abstract

The invention relates to the technical field of batteries, and discloses a pole structure, a cover plate assembly and a battery cell. The pole structure comprises a pole body, a first end face is formed at the first end in the thickness direction, and a groove is formed in the first end face; the heat insulation part is arranged in the groove; the welding plate abuts against the first end of the pole body, at least part of the welding plate is welded to the first end face, and the welding plate is suitable for covering the opening of the groove. After the welding plate and the pole body are welded, the heat insulation piece is sealed in the groove, the overall structure stability is good, electrical connection of the welding plate and the pole body is achieved, and under the blocking effect of the heat insulation piece, transfer of heat generated when the welding plate and the pole lug are welded to the pole body can be slowed down; therefore, heat transferred to the sealing ring through the pole body is reduced, sealing failure caused by hot melting deformation of the sealing ring is avoided, and the sealing reliability of the sealing ring is ensured.

Description

Technical Field

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

[0002] The pole structure is a critical component of the battery cell. It is assembled with the cover plate, rivet block, upper and lower plastics, and sealing ring to form the cover plate assembly. The pole structure is inserted into the pole hole in the cover plate, and the sealing ring is fitted over the pole structure to ensure a tight seal between the pole structure and the cover plate. Traditional pole structures are typically cylindrical. Existing technologies have transformed cylindrical poles into racetrack-shaped pole structures to meet high current requirements.

[0003] However, since the runway-type pole needs to withstand a large current, the welding of the pole base plate and the pole ear must also be able to withstand a large current, which makes the welding melting area of ​​the pole ear and the base plate larger, and the welding heat generation is large. The high temperature generated by the welding will be transmitted along the pole to the sealing ring. The sealing ring is easily affected by the heat and deformed by heat melting, resulting in sealing failure, and then causing the battery cell to fail. Summary of the Invention

[0004] In view of this, the present invention provides a pole structure, a cover plate assembly and a battery cell to solve the problem that the welding heat generated by welding the pole structure and the tab is easily transferred to the sealing ring, resulting in sealing failure.

[0005] In a first aspect, the present invention provides a pole structure, comprising: a pole body, a first end face formed along the first end in the thickness direction, a groove being provided on the first end face; a heat insulating member arranged in the groove; a welding plate abutting the first end of the pole body, at least a portion of the welding plate being welded to the first end face, and the welding plate being suitable for covering the opening of the groove.

[0006] Beneficial effect: by opening a groove on the first end face of the pole body, placing a heat insulating member in the groove, and arranging a welding plate to be welded to the first end face of the pole body, and the welding plate can cover the open end of the groove, after the welding plate is welded to the pole body, the heat insulating member is sealed in the groove, the overall structural stability is better, and the electrical connection between the welding plate and the pole body is realized. After the welding plate is welded to the pole ear, the electrical connection between the pole body and the pole group is realized. Moreover, under the barrier effect of the heat insulating member, the heat generated when the welding plate and the pole ear are welded can be slowed down to transfer to the pole body, thereby reducing the heat transferred to the sealing ring through the pole body, avoiding the sealing failure caused by thermal melting deformation of the sealing ring, ensuring the sealing reliability of the sealing ring, and ensuring the qualified rate of the battery cell.

[0007] In an optional embodiment, the pole body includes a plate and a column, the surface of the plate facing away from the column is the first end face, and the welding plate is arranged on the side of the plate facing away from the column.

[0008] Beneficial effects: By providing the pole body including a plate body and a column body, it is convenient to assemble the pole body with the cover plate body and the riveted block, and in the cross section perpendicular to the thickness direction, the cross-sectional area of ​​the plate body is larger than the cross-sectional area of ​​the column body, which is convenient for welding with the welding plate and facilitating the setting of the groove, thereby increasing the cross-sectional area of ​​the heat insulation area provided by the groove and improving the heat insulation effect.

[0009] In an optional embodiment, the surface of the welding plate on one side facing away from the plate body is a second end face, and the area where the welding plate is welded to the plate body forms a first weld mark on the welding plate; along the thickness direction of the welding plate, the projection area of ​​the first weld mark on the second end face is S1; the column includes a rod portion connected to the plate body, and the cross-sectional area of ​​the rod portion in the section perpendicular to the thickness direction is S2, wherein the relationship between S2 and S1 satisfies the following equation: 1≤S2 / S1≤1.1.

[0010] Beneficial effect: By limiting the value of S2 / S1 to the range of 1 to 1.1, it is possible to avoid excessive temperature rise of the pole body during the charging and discharging process of the battery cell, thereby controlling the heat generation of the battery cell and improving the safety of the battery cell, and to avoid the design of the pole being too redundant, thereby saving costs.

[0011] In an optional embodiment, the welding plate is suitable for welding with the tab to form a second weld mark on the welding plate; the first weld mark is distributed on both sides of the welding plate along the width direction, and the second weld mark is located in the middle position of the welding plate along the width direction; the size of the first weld mark along the width direction is e, the size of the second weld mark along the width direction is d, and the size of the groove along the width direction is c; wherein, the relationship between e, c and d satisfies the formula: 2e≤d≤c.

[0012] Beneficial effect: By setting d greater than 2e, that is, the width of the second weld mark is greater than the total width of the first weld mark, it can be ensured that the flow area between the tab and the welding plate is not less than the welding flow area between the welding plate and the pole body, so that the flow capacity between the tab and the welding plate is not less than the flow capacity between the welding plate and the pole body, avoiding the safety risk caused by the high flow temperature rise at the second weld mark during the charging and discharging of the battery cell. At the same time, by limiting c to be greater than or equal to d, that is, the insulation width formed by the groove is greater than or equal to the width of the weld mark of the pole structure and the tab welding, the heat of the tab welding can be effectively isolated.

[0013] In an optional embodiment, the dimension e of the first weld mark along the width direction is in the range of: 0.8 mm ≤ e ≤ 3 mm;

[0014] And / or, the dimension d of the second weld mark along the width direction has a value range of: 0.8 mm ≤ d ≤ 3 mm.

[0015] Beneficial effect: By limiting the value of e to between 0.8 mm and 3 mm, it is possible to ensure that the minimum width requirement for laser welding is met, thereby facilitating the welding of the plate body 110 and the welding plate 3, while also avoiding wasting welding energy and saving costs;

[0016] And / or, by limiting d to a value between 0.8 mm and 3 mm, it is possible to ensure that the minimum width requirement for laser welding is met, thereby facilitating welding of the tab and the welding plate, while also avoiding wasting welding energy and saving costs.

[0017] In an optional embodiment, the total size of the plate along the thickness direction is h1, and the depth of the groove along the thickness direction is h2, wherein h2 and h1 satisfy the relationship: 0.15≤h2 / h1≤0.3.

[0018] Beneficial effect: By limiting the value of h2 / h1 to between 0.15 and 0.3, the groove depth has a reasonable proportion in the thickness of the plate, which can ensure that the groove can provide sufficient installation space for the thermal insulation component, thereby ensuring the thermal insulation effect, and avoid the groove depth being too large, which will lead to the structural strength of the plate being too low, thereby ensuring the reliability of the pole structure and avoiding failure of the pole structure.

[0019] In an optional embodiment, the dimension of the thermal insulation component along the thickness direction is h3, wherein h3 and h2 satisfy the relationship: 0.05mm≤h2-h3≤0.1mm.

[0020] Beneficial effect: By limiting the value of h2-h3 to the range of 0.05mm to 0.1mm, the thickness of the thermal insulation is slightly smaller than the groove depth of the groove, which can ensure that the depth of the groove can accommodate the flatness of the thermal insulation and ensure that the thermal insulation can be smoothly installed in the groove, and can also avoid the plate body occupying too much internal space of the battery cell along the thickness direction, thereby ensuring the volume energy density of the battery cell.

[0021] In an optional embodiment, the dimension h3 of the thermal insulation member along the thickness direction is in the range of: 0.1 mm ≤ h3 ≤ 0.4 mm;

[0022] And / or, the total dimension h1 of the plate body along the thickness direction has a value range of: 1 mm ≤ h1 ≤ 2 mm;

[0023] And / or, the dimension of the welding plate along the thickness direction is h4, wherein the value range of h4 is: 0.8mm≤h4≤2mm.

[0024] Beneficial effect: By limiting the value of h3 to 0.1mm and 0.4mm, it is possible to ensure that the thermal insulation component can be smoothly processed and formed and has sufficient thermal insulation effect, while also preventing the thermal insulation component from occupying too much space in the plate along the thickness direction, thereby ensuring the structural strength of the plate and ensuring that the pole body meets the push-pull force test;

[0025] And / or, by limiting h1 to a value between 1 mm and 2 mm, the plate body is ensured to have a reasonable thickness, which can ensure that the grooves provided on the plate body have sufficient groove depth, thereby providing sufficient thermal insulation space, ensuring smooth installation of the thermal insulation component, ensuring sufficient thermal insulation effect, and ensuring that the pole body has sufficient strength and the push-pull force meets the use requirements, while avoiding material waste, saving costs, and reducing weight;

[0026] And / or, by limiting the value of h4 to the range of 0.8mm to 2mm, the structural strength of the welding plate can be ensured, avoiding the welding plate being welded through when welding to the tab or plate body, and the welding plate can be avoided from occupying too much internal space of the battery cell along the thickness direction, thereby reserving sufficient setting space for the electrode group, which is conducive to increasing the volume energy density of the battery cell.

[0027] In a second aspect, the present invention further provides a cover plate assembly comprising: a cover plate body having a pole hole defined therein; a rivet block disposed on one side of the cover plate body, the rivet block having a rivet hole defined therein corresponding to the pole hole; the aforementioned pole structure, wherein the pole structure's plate body is located on a side of the cover plate body facing away from the rivet block, and a pole body is inserted into the pole hole and the rivet hole; and a sealing ring is fitted over the pole body. Because the cover plate assembly includes the pole structure and has the same function as the pole, further description thereof will not be given here.

[0028] In a third aspect, the present invention further provides a battery cell comprising: a housing having an open end; an electrode group disposed within the housing; and the aforementioned cover plate assembly, the cover plate assembly being disposed over the open end of the housing. Because the battery cell includes the cover plate assembly, it has the same effects as the cover plate assembly and is not further described here. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 This is a structural diagram of the cover plate assembly and the electrode group welding before improvement;

[0031] Figure 2 This is a schematic structural diagram of a pole structure according to an embodiment of the present invention;

[0032] Figure 3 for Figure 2 An exploded view of the pole structure is shown;

[0033] Figure 4 for Figure 2 A front view of the pole structure shown;

[0034] Figure 5 for Figure 4 Cross-sectional view in the AA direction;

[0035] Figure 6 for Figure 4 Cross-sectional view in the middle BB direction;

[0036] Figure 7 for Figure 2 A bottom view of the pole structure shown;

[0037] Figure 8 for Figure 7 Cross-sectional view in the FF direction;

[0038] Figure 9 This is a front view of a pole body according to an embodiment of the present invention;

[0039] Figure 10 for Figure 9 Cross-sectional view in the GG direction;

[0040] Figure 11 for Figure 9 A bottom view of the pole body is shown;

[0041] Figure 12 A top view of a thermal insulation member according to an embodiment of the present invention;

[0042] Figure 13 for Figure 12 a front view of the thermal insulation shown;

[0043] Figure 14 An exploded view of a cover plate assembly according to an embodiment of the present invention;

[0044] Figure 15 The figure is a schematic structural diagram of a sealing ring according to an embodiment of the present invention.

[0045] Description of reference numerals:

[0046] 1. Pole body; 101. Groove; 110. Plate body; 111. First end face; 120. Column; 121. Rod; 122. Head; 2. Thermal insulation; 3. Welding plate; 310. Second end face; 301. First weld mark; 302. Second weld mark; 4. Cover body; 401. Pole hole; 5. Riveting block; 501. Riveting hole; 6. Sealing ring; 601. First ring portion; 602. Second ring portion; 7. First plastic part; 701. First through hole; 8. Second plastic part; 801. Second through hole; 9. Explosion-proof valve; 901. Explosion-proof patch; 10. Pole group; 1001. Tab; 1002. Tab weld mark. DETAILED DESCRIPTION

[0047] 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.

[0048] Lithium-ion battery is a type of battery. As lithium-ion battery technology becomes increasingly mature, lithium-ion batteries are widely used as power batteries in electric vehicles and energy storage fields. The requirements for the performance and safety of lithium-ion batteries are increasing. The cover assembly is a key component in lithium-ion batteries. Its function is to weld with the shell to form a sealed cavity, lead out the positive and negative electrodes of the electrode group, and serve as an assembly carrier. Figure 1 As shown, it is a schematic diagram of the positional relationship of the welding between the pole group 10 and the pole structure in the cover plate assembly before improvement. The pole ear 1001 is welded to the plate body 110 of the pole structure, and a pole ear weld mark 1002 is formed on the pole ear 1001 and the plate body 110. For the runway-type pole in the cover plate assembly, since the runway-type pole needs to withstand a large current, the welding of the plate body 110 and the pole ear 1001 must also be able to withstand a large current, which makes the welding melting area of ​​the pole ear 1001 and the plate body 110 larger, and the welding heat generation is larger. The high temperature generated by the welding will be transmitted along the pole to the sealing ring 6. The sealing ring 6 is affected by a large amount of welding heat and is easily deformed by heat melting, resulting in sealing failure, and then causing the sealing performance of the battery cell to be unqualified.

[0049] The following combination Figures 2 to 15 , describing embodiments of the present invention.

[0050] According to an embodiment of the present invention, on the one hand, a pole structure is provided, such as Figures 1 to 13As shown, the pole structure includes: a pole body 1, a thermal insulator 2, and a welding plate 3. The pole body 1 forms a first end surface 111 at its first end along the thickness direction, with a groove 101 defined thereon. The thermal insulator 2 is disposed within the groove 101. The welding plate 3 abuts the first end of the pole body 1, with at least a portion of the welding plate 3 welded to the first end surface 111 and adapted to cover the opening of the groove 101.

[0051] It should be noted that the thickness direction refers to Figures 4 and 5 and Figures 8 to 10 The "thickness direction" indicated by the middle arrow is in the same direction as the axis of the column 120; the pole body 1 has a first end and a second end arranged opposite to each other along the thickness direction. When the pole structure and other components are assembled into a battery cell, the first end of the pole body 1 faces the inside of the battery cell shell, and the second end faces the outside of the shell. The welding plate 3 connected to the first end of the pole body 1 is welded to the pole ear 1001; the groove 101 is formed by a partial area on the first end face 111 being recessed toward the second end along the thickness direction, and the opening area of ​​the groove 101 is smaller than the surface area of ​​the first end face 111; a sealing ring 6 is provided on the pole body 1 to ensure the sealing between the pole body 1 and the cover body 4.

[0052] The pole structure of this embodiment is applied, by opening a groove 101 on the first end face 111 of the pole body 1, placing a heat insulating member 2 in the groove 101, and arranging a welding plate 3 to be welded to the first end face 111 of the pole body 1, and the welding plate 3 can cover the open end of the groove 101, then after the welding plate 3 is welded to the pole body 1, the heat insulating member 2 is enclosed in the groove 101, the overall structural stability is good, and the electrical connection between the welding plate 3 and the pole body 1 is achieved, and after the welding plate 3 is welded to the pole ear 1001, the electrical connection between the pole body 1 and the pole group is achieved, and under the blocking effect of the heat insulating member 2, the heat generated when the welding plate 3 is welded to the pole ear 1001 can be slowed down to transfer to the pole body 1, thereby reducing the heat transferred to the sealing ring 6 through the pole body 1, avoiding the sealing failure caused by the thermal melting deformation of the sealing ring 6, ensuring the sealing reliability of the sealing ring 6, and ensuring the qualified rate of the battery cell.

[0053] In one embodiment, the heat insulating member 2 is in sheet form and can be stably embedded in the groove 101. Optionally, the heat insulating member 2 is made of mica sheet, ceramic fiber, etc.

[0054] In one embodiment, the pole body 1 includes a plate 110 and a column 120. The surface of the plate 110 facing away from the column 120 is a first end surface 111. The welding plate 3 is disposed on the side of the plate 110 facing away from the column 120. It should be noted that the outer periphery of the column 120 is smaller than that of the plate 110, and the outer periphery of the plate 110 is larger than the opening of the pole hole 401. The end of the column 120 away from the plate 110 is riveted to the rivet block 5, and the outer periphery of the rivet block 5 is larger than the opening of the pole hole 401, thereby achieving mutual restraint between the pole structure, the cover plate body 4, and the rivet block 5. By providing the pole body 1 with a plate body 110 and a column body 120, it is convenient to assemble the pole body 1 with the cover plate body 4 and the riveted block 5. In addition, in a cross section perpendicular to the thickness direction, the cross-sectional area of ​​the plate body 110 is larger than the cross-sectional area of ​​the column body 120, which facilitates welding with the welding plate 3 and facilitates the provision of the groove 101, thereby increasing the cross-sectional area of ​​the heat-insulating region provided by the groove 101 and improving the heat-insulating effect.

[0055] In addition, in other embodiments, the pole body 1 may also not be provided with the plate body 110, the first end of the column 120 forms the first end face 111, and the welding plate 3 is directly welded to the column 120. The cross-sectional area of ​​the welding plate 3 can be set to be larger than the cross-sectional area of ​​the column 120 and the opening area of ​​the pole hole 401, and the mutual limitation between the pole structure, the cover plate body 4 and the rivet block 5 can also be achieved.

[0056] In one embodiment, the side surface of the welding plate 3 facing away from the plate body 110 is the second end surface 310, and the area where the welding plate 3 is welded to the plate body 110 forms a first weld mark 301 on the welding plate 3; along the thickness direction of the welding plate 3, the projection area of ​​the first weld mark 301 on the second end surface 310 is S1; the column 120 includes a rod portion 121 connected to the plate body 110, and the cross-sectional area of ​​the rod portion 121 in the section perpendicular to the thickness direction is S2, wherein S2 and S1 satisfy the relationship: 1≤S2 / S1≤1.1. The units of S1 and S2 are both mm 2 . The thickness direction refers to Figures 4 and 5 and Figure 8 The arrow in the middle indicates the "thickness direction".

[0057] It should be noted that the column 120 also includes a head 122, and the rod 121 is connected between the head 122 and the plate 110. The head 122 is inserted into the rivet hole 501 on the rivet block 5 and connected to the rivet block 5. The rod 121 is supported between the rivet block 5 and the plate 110. The larger the cross-sectional area S2 of the rod 121, the stronger the current carrying capacity of the rod 121. The welding plate 3 is electrically connected to the pole body 1 through the first weld mark 301. The projection area S2 of the orthographic projection of the first weld mark 301 on the second end face 310 is The larger 1 is, the stronger the flow capacity between the welding plate 3 and the pole body 1 is; the size of S1 and S2 is related to the capacity of the battery cell, the rate, etc. When the size of S1 just meets the flow capacity requirement of the battery cell, if S2 / S1 is less than 1, the flow capacity of the rod 121 is less than the flow capacity of the welding area of ​​the welding plate 3 and the pole body 1, which will cause the temperature rise of the rod 121 to be too high and the battery cell to generate too much heat, thereby affecting the safety of the battery cell; if S2 / S1>1.1, the cross-sectional area design of the rod 121 is too redundant, and the cost increases.

[0058] Therefore, by limiting the value of S2 / S1 to the range of 1 to 1.1, it is possible to avoid excessive temperature rise of the rod portion 121 of the pole body 1 during the charging and discharging process of the battery cell, thereby controlling the heat generation of the battery cell and improving the safety of the battery cell, and to avoid the design of the rod portion 121 being too redundant, thereby saving costs.

[0059] Optionally, the value of S2 / S1 is any value among 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, or a value between any two values.

[0060] Further integration Figure 7 As shown, the length of the first weld mark 301 is L, the width of the first weld mark 301 is e, and there are two first weld marks 301, which are spaced apart along the width direction. Then S1 = 2Le, where L and e are both in mm. It should be noted that the cross section of the rod portion 121 is runway-shaped or circular, including at least two semicircular areas opposite to each other along the length direction. S2 = πr 2 +nr, where r is the radius of the semicircle area, n is the center distance between the two semicircles, and the units of r and n are both mm; further combined Figure 6 As shown, when the cross section of the rod 121 is runway-shaped, it includes two semicircular areas arranged opposite to each other along the length direction and a rectangular area connected between the two semicircular areas; when the cross section of the rod 121 is circular, n=0. The length direction refers to Figure 6 、 Figure 7 The arrow in the middle refers to the "length direction", and the width direction refers to Figure 6 、 Figure 7The arrow in the middle points to the "width direction".

[0061] In one embodiment, the width dimension e of the first weld mark 301 is in the range of 0.8 mm ≤ e ≤ 3 mm. It should be noted that the plate body 110 and the welding plate 3 are connected by laser welding, and the first weld mark 301 is formed by laser welding. If e is less than 0.8 mm, the minimum width requirement for laser welding is not met, making welding difficult. If e is greater than 3 mm, the width dimension of the first weld mark 301 is too large, wasting welding energy and increasing costs. Therefore, by limiting e to a value between 0.8 mm and 3 mm, the minimum width requirement for laser welding can be met, thereby facilitating welding of the plate body 110 and the welding plate 3, while also avoiding wasted welding energy and saving costs.

[0062] In one embodiment, the length L of the first weld mark 301 is in the range of 10 mm ≤ L ≤ 35 mm. If L is less than 10 mm, the length of the first weld mark 301 is too small, resulting in a projected area S1 of the orthographic projection of the first weld mark 301 on the second end surface 310 being too small and unable to meet the overcurrent requirements of the battery cell. If L is greater than 35 mm, the length of the first weld mark 301 is too large, wasting welding energy and increasing costs. Furthermore, the first weld mark 301 is too close to the edges of the welding plate 3 along the length direction, which can easily lead to poor welding. Therefore, by limiting L to a value within the range of 10 mm to 35 mm, it is possible to ensure that the first weld mark 301 can meet the overcurrent requirements of the battery cell while avoiding wasting welding energy, saving costs, and improving welding yield.

[0063] In one embodiment, the radius r of the semicircular area on the cross section of the rod portion 121 on the cross section perpendicular to the thickness direction is in the range of 2mm≤r≤10mm, which limits the cross section of the rod portion 121 to a reasonable size. This can avoid the cross-sectional area of ​​the rod portion 121 being too small, which may cause insufficient flow capacity of the rod portion 121, and can also avoid the cross-sectional area of ​​the rod portion 121 being too large, which may cause waste of material and increase in weight. This can ensure that the rod portion 121 can meet the flow capacity of the battery cell, avoid waste of material, and save costs.

[0064] In one embodiment, the cross-section of the rod portion 121 perpendicular to the thickness direction is racetrack-shaped. The length dimension n of the rectangular area between the two semicircular areas is in the range of 0 < n ≤ 15 mm. If n = 0, the cross-section of the rod portion 121 is circular, rather than racetrack-shaped, resulting in a smaller cross-sectional area and poor current flow capacity. If n is greater than 15 mm, the length dimension of the rod portion 121 is too large, wasting material and making it difficult to manufacture. Therefore, by limiting the range to 0 < n ≤ 15 mm, it is possible to ensure that the rod portion 121 can meet the current flow capacity of the battery cell while avoiding material waste and saving costs.

[0065] In this embodiment, the rod portion 121 is runway-shaped. The following examples illustrate the effects of different values ​​of S2 / S1 on the performance of the pole structure. The measurement results of the embodiment and the comparative example are shown in Tables 1 to 3. Among them, the pole structure of the embodiment satisfies the relationship of 1≤S2 / S1≤1.1; the pole structure of the comparative example does not satisfy the relationship of 1≤S2 / S1≤1.1.

[0066] Case 1: L = 20mm, e = 1mm, S1 meets the minimum overcurrent requirement of the battery cell; r = 2.3mm. By taking different values ​​of n, different values ​​of S2 / S1 are obtained. Under different S2 / S1 values, whether the maximum temperature T of the terminal structure after charging and discharging the battery cell meets the requirement (≤55°C) is compared. The weight of the terminal structure is also compared. The results are shown in Table 1.

[0067] Table 1

[0068]

[0069] Case 2: L = 22mm, e = 1mm, S1 meets the minimum overcurrent requirement of the battery cell; r = 2.8mm. By taking different values ​​of n, different values ​​of S2 / S1 are obtained. Under different S2 / S1 values, whether the maximum temperature T of the terminal structure after charging and discharging the battery cell meets the requirement (≤55°C) is compared. The weight of the terminal structure is also compared. The results are shown in Table 2.

[0070] Table 2

[0071]

[0072]

[0073] Case 3: L = 22mm, e = 1.2mm, S1 meets the minimum overcurrent requirement of the battery cell; r = 2.8mm. By taking different values ​​of n, different values ​​of S2 / S1 are obtained. Under different S2 / S1 values, whether the maximum temperature T of the terminal structure after charging and discharging the battery cell meets the requirement (≤55°C) is compared. The weight of the terminal structure is also compared. The results are shown in Table 3.

[0074] Table 3

[0075]

[0076] It can be seen from Tables 1 to 3 that in Examples 1-1 to 1-5, 2-1 to 2-5, and 3-1 to 3-5, the values ​​of S2 / S1 are all within the range of 1 to 1.1 as defined in this application. After the battery core is charged and discharged, the maximum temperature T of the pole structure is less than or equal to 55°C, which meets the temperature requirements, and the pole structure is overweight; while in Comparative Examples 1-1 to 1-3, 2-1 to 2-3, and 3-1 to 3-3, the values ​​of S2 / S1 are all within the range of 1 to 1.1 as defined in this application. Less than 1, not within the scope defined in the present application, although the pole structure is not overweight, the maximum temperature T of the pole structure after charging and discharging the battery cell is greater than 55°C, which does not meet the temperature requirements and is highly dangerous; in Comparative Examples 1-4 to 1-6, Comparative Examples 2-4 to 2-6, and Comparative Examples 3-4 to 3-6, the values ​​of S2 / S1 are all greater than 1.1, not within the scope defined in the present application, although the maximum temperature T of the pole structure after charging and discharging the battery cell does not exceed 55°C, the pole structure is overweight and does not meet the requirements.

[0077] In summary, when S2 / S1 is in the range of 1 to 1.1, the maximum temperature of the pole structure after charging and discharging of the battery cell and the weight of the pole structure can meet the requirements, and the battery cell performance is good.

[0078] In one embodiment, further combined Figure 7 and Figure 10 As shown, the welding plate 3 is suitable for welding with the tab 1001 to form a second weld mark 302 on the welding plate 3; the first weld mark 301 is distributed on both sides of the welding plate 3 along the width direction, and the second weld mark 302 is located in the middle position of the welding plate 3 along the width direction; the size of the first weld mark 301 along the width direction is e, the size of the second weld mark 302 along the width direction is d, and the size of the groove 101 along the width direction is c; wherein, the relationship between e, c and d satisfies the formula: 2e≤d≤c. It should be noted that the groove 101 is opened in the middle position of the first end face 111, and the portion of the first end face 111 outside the groove 101 area can be used for welding with the welding plate 3. The first weld mark 301 is located on both sides of the welding plate 3 along the width direction, which conforms to the distribution characteristics of the groove 101 and facilitates the welding of the welding plate 3 and the first end face 111. At the same time, by arranging the second weld mark 302 in the middle position of the welding plate 3 along the width direction, it will not interfere with the first weld mark 301, and can provide sufficient setting space for the second weld mark 302, thereby ensuring the flow capacity between the pole group and the welding plate 3, and can make the second weld mark 302 correspond to the groove 101 and the thermal insulation member 2, thereby effectively isolating the welding heat generated during the formation of the second weld mark 302.

[0079] Among them, by setting d greater than 2e, that is, the width of the second weld mark 302 is greater than the total width of the first weld mark 301, it can be ensured that the flow area between the pole tab 1001 and the welding plate 3 is not less than the welding flow area between the welding plate 3 and the pole body 1, so that the flow capacity between the pole tab 1001 and the welding plate 3 is not less than the flow capacity between the welding plate 3 and the pole body 1, avoiding the high flow temperature rise at the second weld mark 302 during the charging and discharging of the battery cell and causing safety risks. At the same time, by limiting c to be greater than or equal to d, that is, the insulation width formed by the groove 101 is greater than or equal to the weld mark width of the pole structure and the pole tab 1001, the heat of the pole tab welding can be effectively isolated.

[0080] In one embodiment, the length of the second weld mark 302 is equal to the length of the first weld mark 301. By limiting d ≥ 2e, it is ensured that the flow area between the tab 1001 and the welding plate 3 is not less than the welding flow area between the welding plate 3 and the electrode body 1. It is understood that, as an alternative embodiment, the length of the second weld mark 302 can also be greater or smaller than the length of the first weld mark 301, but it is always necessary to ensure that S2 ≥ S1.

[0081] In one embodiment, the width dimension d of the second weld mark 302 is in the range of 0.8 mm ≤ d ≤ 3 mm. It should be noted that the tab 1001 is connected to the welding plate 3 via laser welding, and the second weld mark 302 is formed by laser welding. If d is less than 0.8 mm, the minimum width requirement for laser welding is not met, making welding difficult. If d is greater than 3 mm, the width dimension of the second weld mark 302 is too large, wasting welding energy and increasing costs. Therefore, by limiting d to a value between 0.8 mm and 3 mm, the minimum width requirement for laser welding can be met, thereby facilitating welding of the tab 1001 to the welding plate 3, while also avoiding wasted welding energy and saving costs.

[0082] In one embodiment, further combined Figure 10 As shown, the total size of the plate 110 along the thickness direction is h1, and the depth of the groove 101 along the thickness direction is h2, wherein h2 and h1 satisfy the relationship: 0.15≤h2 / h1≤0.3. Figure 10The arrow in the middle indicates the "thickness direction"; h1 and h2 are both in mm. It should be noted that if the ratio h2 / h1 is less than 0.15, the depth of the groove 101 is too small relative to the thickness of the plate 110, leaving insufficient space for the thermal insulation element 2 and poor insulation. If h2 / h1 is greater than 0.3, the depth of the groove 101 accounts for too large a proportion of the thickness of the plate 110. This makes the remaining portion of the plate 110 after removing the groove 101 in the thickness direction too thin, resulting in insufficient structural strength and a risk of failure. Therefore, by limiting the value of h2 / h1 to between 0.15 and 0.3, the depth of the groove 101 has a reasonable proportion in the thickness of the plate body 110, which can not only ensure that the groove 101 can provide sufficient installation space for the thermal insulation component 2, thereby ensuring the thermal insulation effect, but also avoid the groove depth of the groove 101 being too large, which will cause the structural strength of the plate body 110 to be too small, thereby ensuring the reliability of the pole structure and avoiding failure of the pole structure.

[0083] Optionally, the value of h2 / h1 is any value among 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, or a value between any two values.

[0084] In one embodiment, the total dimension h1 of the plate body 110 along the thickness direction has a value range of: 1mm≤h1≤2mm. It should be noted that the total dimension h1 of the plate body 110 along the thickness direction refers to the dimension of the portion of the plate body 110 along the thickness direction where the groove 101 is not provided. If h1 is less than 1mm, the thickness of the plate body 110 is too small, and the depth of the groove 101 provided on the plate body 110 is correspondingly too small. The insulation space is insufficient, and the insulation component 2 cannot be installed. In addition, the strength of the plate body 110 is insufficient, and the push-pull force does not meet the use requirements. If h1 is greater than 2mm, the thickness of the plate body 110 is too large, the design of the pole body 1 is redundant, the weight of the pole body 1 increases, and materials are wasted. Therefore, by limiting h1 to a value between 1 mm and 2 mm, the plate body 110 is ensured to have a reasonable thickness, which can ensure that the groove 101 opened on the plate body 110 has a sufficient groove depth, thereby providing sufficient insulation space, ensuring that the insulation member 2 is smoothly installed, ensuring sufficient insulation effect, and ensuring that the pole body 1 has sufficient strength, and the push-pull force meets the use requirements, while avoiding waste of materials, saving costs, and reducing weight.

[0085] Optionally, the value of h1 is any value among 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, or a value between any two values.

[0086] The following examples illustrate the effects of different values ​​of h2 / h1 on the electrode structure and cell performance. The measurement results of the embodiments and comparative examples are shown in Tables 4 to 6. The electrode structure of the embodiments satisfies the relationship of 0.15≤h2 / h1≤0.3, while the electrode structure of the comparative example does not satisfy the relationship of 0.15≤h2 / h1≤0.3.

[0087] Case 4: h1 = 1mm, adjust the value of h2 to obtain different values ​​of h2 / h1, assemble the battery cell with this pole structure, and measure whether the helium leak rate of the battery cell meets the requirements (≤1×10 -7 Pa.m 3 / s), and whether the terminal structure can withstand push and pull forces that meet the requirements (≥800N). The test results are shown in Table 4. It should be noted that the terminal structure, as a key component in the battery, must be able to withstand a certain degree of push and pull forces without damage, loosening, or poor contact, to ensure the reliability of the battery's electrical connection and mechanical stability during use.

[0088] Table 4

[0089]

[0090] Case 5: h1 = 1.1 mm. Adjust the value of h2 to obtain different values ​​of h2 / h1. Assemble the battery cell with this pole structure and measure whether the helium leak rate of the battery cell meets the requirements (≤1×10 -7 Pa.m 3 / s), and whether the pole structure can withstand the push and pull forces that meet the requirements (≥800N). The test results are shown in Table 5.

[0091] Table 5

[0092]

[0093]

[0094] Case 6: h1 = 0.9 mm, adjust the value of h2 to obtain different values ​​of h2 / h1, assemble the battery cell with this pole structure, and measure whether the helium leak rate of the battery cell meets the requirements (≤1×10 -7 Pa.m 3 / s), and whether the pole structure can withstand the push and pull forces that meet the requirements (≥800N). The test results are shown in Table 6.

[0095] Table 6

[0096]

[0097] It can be seen from Tables 4 to 6 that in Examples 4-1 to 4-5, 5-1 to 5-5, and 6-1 to 6-5, the values ​​of h2 / h1 are all within the range of 0.15 to 0.3 as defined in this application, and the helium leak detection rates of the battery cells are all less than or equal to 1×10 -7 Pa.m 3 / s, which meets the requirements, and the pole structure can withstand a push-pull force greater than or equal to 800N, which meets the requirements; while in Comparative Examples 4-1 to 4-3, Comparative Examples 5-1 to 5-3, and Comparative Examples 6-1 to 6-3, the values ​​of h2 / h1 are all less than 0.15, which are not within the scope defined in this application. Although the pole structure can withstand a push-pull force greater than or equal to 800N, the helium leak detection rate of the battery cell is greater than 1×10 -7 Pa.m 3 / s, which does not meet the requirements, and the battery cell helium test fails, indicating that the sealing ring is melted by the welding heat and the seal fails; in Comparative Examples 4-4 to 4-6, Comparative Examples 5-4 to 5-6, and Comparative Examples 6-4 to 6-6, the values ​​of h2 / h1 are all greater than 0.3, which are not within the scope defined in this application. Although the helium leakage rate of the battery cells is less than or equal to 1×10-7Pa.m3 / s, the push-pull force that the pole structure can withstand is less than 800N, which does not meet the push-pull force requirements. The pole structure is insufficient in strength and is prone to failure during the use of the battery cell.

[0098] In summary, when h2 / h1 is within the range of 0.15 to 0.3, the helium leak detection rate of the battery cell and the push-pull force of the electrode structure can meet the use requirements, the battery cell production is qualified, and the safety and reliability are high.

[0099] In one embodiment, further combined Figure 13As shown, the dimension of the thermal insulation member 2 along the thickness direction is h3, wherein h3 and h2 satisfy the relationship: 0.05mm≤h2-h3≤0.1mm, and the units of h2 and h3 are both mm. It should be noted that the thermal insulation member 2 is installed in the groove 101, and the welding plate 3 is encapsulated in the space between the bottom wall of the groove 101 and the welding plate 3. If h2-h3 is less than 0.05mm, the installation space of the thermal insulation member 2 is insufficient due to the flatness of the welding plate 3, the plate body 110 and the thermal insulation member 2, and the thermal insulation member 2 cannot be encapsulated in the groove 101. If h2-h3 is greater than 0.1mm, the difference between the groove depth of the groove 101 and the thickness of the thermal insulation member 2 is too large, making the total dimension of the plate body 110 along the thickness direction too large, affecting the battery cell space. Therefore, by limiting the value of h2-h3 to the range of 0.05mm to 0.1mm, the thickness of the thermal insulation member 2 is slightly smaller than the groove depth of the groove 101, which can ensure that the depth of the groove 101 can accommodate the flatness of the thermal insulation member 2 and ensure that the thermal insulation member 2 can be smoothly installed in the groove 101, and can also avoid the plate body 110 occupying too much internal space of the battery cell along the thickness direction, thereby ensuring the volume energy density of the battery cell.

[0100] Optionally, the value of h2-h3 is any value among 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, or a value between any two values.

[0101] In one embodiment, the dimension h3 of the thermal insulation member 2 along the thickness direction has a value range of: 0.1mm≤h3≤0.4mm. If h3 is less than 0.1mm, the thermal insulation member 2 is difficult to process and the thermal insulation effect is poor; if h3 is greater than 0.4mm, the thermal insulation member 2 is redundant in design and occupies too much space of the plate body 110 along the thickness direction, affecting the push-pull force of the pole body 1. Therefore, by limiting the value of h3 to be within the range of 0.1mm to 0.4mm, it can be ensured that the thermal insulation member 2 is smoothly processed and formed, and that the thermal insulation member 2 has sufficient thermal insulation effect, while avoiding the thermal insulation member 2 from occupying too much space of the plate body 110 along the thickness direction, thereby ensuring the structural strength of the plate body 110 and ensuring that the pole body 1 meets the push-pull force test.

[0102] Optionally, the value of h3 is any value among 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, or a value between any two values.

[0103] In one embodiment, further combined Figure 5 and Figure 8As shown, the dimension of the thermal insulation member 2 along the length direction is smaller than the dimension of the groove 101 along the length direction, and the dimension of the thermal insulation member 2 along the width direction is smaller than the dimension of the groove 101 along the width direction, and both are slightly smaller, so that there is a gap between the thermal insulation member 2 and the side wall of the groove 101, which facilitates the installation of the thermal insulation member 2 into the groove 101 and provides a certain margin for the manufacturing tolerance and thermal deformation of the thermal insulation member 2, and the gap between the side wall of the groove 101 and the thermal insulation member 2 is air, which also has a certain thermal insulation effect.

[0104] In one embodiment, further combined Figure 5 As shown, the dimension of the welding plate 3 along the thickness direction is h4, where the value range of h4 is: 0.8mm≤h4≤2mm. If h4 is less than 0.8mm, the thickness of the welding plate 3 is too small, and the welding plate 3 may be welded through when welding the welding plate 3 to the tab 1001 or the plate body 110. If h4 is greater than 2mm, the thickness of the welding plate 3 is too large, occupying too much space inside the battery cell and affecting the volumetric energy density of the battery cell. Therefore, by limiting the value of h4 to a range of 0.8mm to 2mm, the structural strength of the welding plate 3 can be ensured, preventing the welding plate 3 from being welded through when welding to the tab 1001 or the plate body 110, while also preventing the welding plate 3 from occupying too much space inside the battery cell along the thickness direction, thereby reserving sufficient space for the electrode assembly and facilitating an increase in the volumetric energy density of the battery cell.

[0105] Optionally, the value of h4 is any value among 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, or a value between any two values.

[0106] According to an embodiment of the present invention, on the other hand, a cover plate assembly is provided. Figures 14 and 15 As shown, the cover assembly includes: a cover body 4, a rivet block 5, the aforementioned pole structure, and a sealing ring 6. The cover body 4 defines a pole hole 401; the rivet block 5 is disposed on one side of the cover body 4 and defines a rivet hole 501 corresponding to the pole hole 401. The plate 110 of the pole structure is located on the side of the cover body 4 facing away from the rivet block 5, with the pole 120 inserted through the pole hole 401 and the rivet hole 501. The sealing ring 6 is sleeved onto the pole 120. Specifically, the sealing ring 6 sleeves onto the outer periphery of the rod 121 of the rod 120 and is located between the rod 121 and the cover body 4.

[0107] The cover plate assembly of this embodiment can improve the influence of the high temperature generated when the tab 1001 is welded to the pole structure on the sealing ring 6, and can effectively avoid abnormal sealing performance caused by the sealing ring 6 being melted and deformed by heat, thereby ensuring the sealing performance of the sealing ring 6 and improving the qualified rate of the battery cell.

[0108] In one embodiment, the sealing ring 6 includes: a first ring portion 601 and a second ring portion 602, the second ring portion 602 is connected to an end of the first ring portion 601 close to the plate body 110, the first ring portion 601 is located between the outer peripheral side of the rod portion 121 and the pole hole 401, and the second ring portion 602 is compressed between the cover body 4 and the plate body 110 to further improve the sealing performance.

[0109] In one embodiment, the cover assembly further includes: a first plastic part 7 and a second plastic part 8, the first plastic part 7 is arranged between the rivet block 5 and the cover body 4 to ensure insulation between the rivet block 5 and the cover body 4, the first plastic part 7 is provided with a first through hole 701 corresponding to the pole hole 401, and the first through hole 701 is for the head 122 of the column 120 to pass through; the second plastic part 8 is arranged on the side of the cover body 4 away from the first plastic part 7, the second plastic part 8 is provided with a second through hole 801, a partial section of the rod 121 of the column 120 close to the plate body 110 is passed through the second through hole 801, the plate body 110 is located on the side of the second plastic part 8 away from the cover body 4, the plate body 110 presses the second plastic part 8 toward the cover body 4, and the second plastic part 8 is used to ensure insulation between the cover body 4 and the pole group.

[0110] In one embodiment, the first plastic part 7 is an upper plastic and the second plastic part 8 is a lower plastic.

[0111] In one embodiment, the cover assembly further includes an explosion-proof valve 9. An explosion-proof valve hole is further provided on the cover body 4. The explosion-proof valve 9 is disposed in the explosion-proof valve hole. The explosion-proof valve 9 is adapted to open when the air pressure inside the battery reaches a preset value, thereby discharging high-temperature flue gas in the battery in a timely manner to prevent the battery from exploding. An explosion-proof patch 901 is affixed to the explosion-proof valve 9 to protect the explosion-proof valve.

[0112] According to another aspect of an embodiment of the present invention, a battery cell is provided, comprising: a housing, an electrode group, and the aforementioned cover plate assembly. The housing has an open end; the electrode group is disposed within the housing; and the cover plate assembly covers the open end of the housing. Preferably, the battery is a lithium battery, used in fields such as electric vehicles and energy storage.

[0113] 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 pole structure, characterized in that: include: The pole body has a first end along the thickness direction thereof forming a first end surface, and a groove is formed on the first end surface; a heat insulating member disposed in the groove; A welding plate is in contact with the first end of the pole body, at least a portion of the welding plate is welded to the first end surface, and the welding plate is suitable for covering the opening of the groove.

2. The pole structure according to claim 1, characterized in that: The pole body includes a plate body and a column body, a surface of the plate body on a side away from the column body is the first end face, and the welding plate is arranged on a side of the plate body away from the column body.

3. The pole structure according to claim 2, characterized in that: The surface of the welding plate facing away from the plate body is a second end surface, and the area where the welding plate is welded to the plate body forms a first weld mark on the welding plate; along the thickness direction of the welding plate, the projected area of ​​the orthographic projection of the first weld mark on the second end surface is S1; The column includes a rod portion connected to the plate body, and the cross-sectional area of ​​the rod portion in a section perpendicular to the thickness direction is S2, wherein S2 and S1 satisfy the relationship: 1≤S2 / S1≤1.

1.

4. The pole structure according to claim 3, characterized in that: The welding plate is suitable for welding with the tab to form a second weld mark on the welding plate; The first weld marks are distributed on both sides of the welding plate along the width direction, and the second weld marks are located in the middle of the welding plate along the width direction; The dimension of the first weld mark along the width direction is e, the dimension of the second weld mark along the width direction is d, and the dimension of the groove along the width direction is c; Among them, the relationship between e, c and d is: 2e≤d≤c.

5. The pole structure according to claim 4, characterized in that: The value range of the dimension e of the first weld mark along the width direction is: 0.8mm≤e≤3mm; And / or, the dimension d of the second weld mark along the width direction has a value range of: 0.8 mm ≤ d ≤ 3 mm.

6. The pole structure according to any one of claims 2 to 5, characterized in that: The total size of the plate along the thickness direction is h1, and the depth of the groove along the thickness direction is h2, wherein h2 and h1 satisfy the relationship: 0.15≤h2 / h1≤0.

3.

7. The pole structure according to claim 6, characterized in that: The dimension of the thermal insulation member in the thickness direction is h3, wherein h3 and h2 satisfy the relationship: 0.05mm≤h2-h3≤0.1mm.

8. The pole structure according to claim 7, characterized in that: The dimension h3 of the thermal insulation member in the thickness direction has a value range of: 0.1 mm ≤ h3 ≤ 0.4 mm; And / or, the total dimension h1 of the plate body along the thickness direction has a value range of: 1 mm ≤ h1 ≤ 2 mm; And / or, the dimension of the welding plate along the thickness direction is h4, wherein the value range of h4 is: 0.8mm≤h4≤2mm.

9. A cover plate assembly, characterized in that: include: The cover body is provided with a pole hole; A rivet block is provided on one side of the cover body, and a rivet hole corresponding to the pole hole is opened on the rivet block; The pole structure according to any one of claims 1 to 8, wherein the plate body of the pole structure is located on a side of the cover body away from the rivet block, and the column body is inserted into the pole hole and the rivet hole; The sealing ring is sleeved on the column.

10. A battery cell, characterized in that: include: a housing having an open end; a pole group, disposed in the housing; The cover plate assembly according to claim 9 is provided to cover the open end of the shell.

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