Lower plastic component, end cover assembly and battery cell

Abstract

The application discloses a lower plastic component, an end cover assembly and a battery cell. The battery cell comprises the end cover assembly. The end cover assembly comprises the lower plastic component. The lower plastic component comprises a main body. The main body is provided with a first surface and a second surface which are oppositely arranged. The first surface is planar and is arranged to be attached to a top cover.

Description

Lower plastic parts, end cover components and battery cells

[0001] This application claims priority to Chinese patent applications filed with the China Patent Office on November 17, 2023, with application numbers 202323131966.2 and 202323131982.1, and the entire contents of the above applications are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a lower plastic part, an end cover assembly, and a battery cell. Background Art

[0003] In the related art, a battery cell includes a shell having a shell opening, an end cap assembly disposed at the shell opening, and an electrode assembly located within the shell. The end cap assembly includes a top cap and a lower plastic part disposed on the top cap near the electrode assembly. The lower plastic part is provided with multiple through-holes, such as an injection hole for injecting electrolyte and an exhaust hole disposed opposite the explosion-proof valve on the top cap. The lower plastic part has a cavity on the side facing the top cap. During injection, the electrolyte passes through the top cap and the lower plastic part and flows directly into the vicinity of the electrode assembly. This results in the cavity between the lower plastic part and the top cap being left empty after the battery cell is injected.

[0004] When connecting multiple battery cells in series, some need to be inverted. When the battery cells are inverted, some electrolyte will flow through the through-holes in the lower plastic part into the space between the lower plastic part and the top cover, filling the cavity. This reduces the level of electrolyte soaking the electrode assembly, resulting in insufficient electrolyte infiltration of the electrode assembly, affecting its performance. SUMMARY OF THE INVENTION

[0005] The present application provides a lower plastic part, an end cover assembly and a battery cell to solve the above technical problems.

[0006] In a first aspect, embodiments of the present application provide a lower plastic component for use in a battery cell having a top cover. The lower plastic component includes a body having a first surface and a second surface disposed opposite to each other, wherein the first surface is planar and configured to mate with the top cover.

[0007] On the second aspect, an embodiment of the present application also provides an end cover assembly, which includes a top cover, an upper plastic part, a terminal, a pole and the aforementioned lower plastic part, wherein the first surface contacts one side of the top cover; the upper plastic part contacts the other side of the top cover; the terminal is located on the side of the upper plastic part away from the top cover; one end of the pole passes through the lower plastic part, the top cover and the upper plastic part in sequence and is connected to the terminal.

[0008] In a third aspect, an embodiment of the present application further provides a battery cell comprising the above-mentioned end cover assembly. Beneficial effects

[0009] The beneficial effects of this application are:

[0010] The lower plastic part provided in the present application is configured to have a planar structure on the first surface where the lower plastic part contacts the top cover, so that the top cover is fitted with the top cover through the first surface. This can prevent the electrolyte from accumulating between the lower plastic part and the top cover after the battery cell is inverted, thereby reducing the impact of the inversion of the battery cell on the immersion of the electrode assembly in the electrolyte, and ultimately improving the problem of insufficient wetting of the electrode assembly after the battery cell is inverted.

[0011] The end cap assembly provided in the present application is configured to have a planar structure with the first surface where the lower plastic part contacts the top cap, so that the top cap is fitted with the top cap through the first surface. This can avoid the electrolyte from accumulating between the lower plastic part and the top cap after the battery cell is inverted, thereby reducing the effect of the inversion of the battery cell on the immersion of the electrode assembly in the electrolyte, and ultimately improving the problem of insufficient wetting of the electrode assembly after the battery cell is inverted.

[0012] The battery cell provided in the present application, by setting the first surface of the lower plastic part in contact with the top cover into a planar structure, so that the top cover is fitted with the top cover through the first surface, thereby avoiding the accumulation of electrolyte between the lower plastic part and the top cover after the battery cell is inverted, thereby reducing the impact of the inversion of the battery cell on the immersion of the electrode assembly in the electrolyte, and ultimately improving the problem of insufficient wetting of the electrode assembly after the battery cell is inverted. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG1 is a schematic structural diagram of a lower plastic part provided in Example 1 of the present application;

[0014] FIG2 is a cross-sectional view along line EE in FIG1 ;

[0015] Figure 3 is an enlarged view of point F in Figure 2;

[0016] FIG4 is a schematic structural diagram of a cross section of a first annular groove provided in Example 1 of the present application;

[0017] FIG5 is an enlarged view of point G in FIG2 ;

[0018] FIG6 is a schematic structural diagram of a cross section of a second annular groove provided in Example 1 of the present application;

[0019] FIG7 is a bottom view of the lower plastic member provided in Example 1 of the present application;

[0020] FIG8 is a schematic structural diagram of an end cap assembly provided in Example 1 of the present application;

[0021] FIG9 is a cross-sectional view taken along line HH in FIG8 ;

[0022] FIG10 is an enlarged view of point I in FIG9;

[0023] FIG11 is an enlarged view of point J in FIG9 ;

[0024] FIG12 is a top view of the lower plastic part provided in Example 2 of the present application;

[0025] FIG13 is a cross-sectional view along AA in FIG1 provided in Example 2 of the present application;

[0026] FIG14 is a schematic structural diagram of the lower plastic member provided in Example 2 of the present application;

[0027] FIG15 is an enlarged view of point B in FIG13;

[0028] FIG16 is a bottom view of the lower plastic member provided in Example 2 of the present application;

[0029] FIG17 is a top view of the end cap assembly provided in Example 2 of the present application;

[0030] Figure 18 is a sectional view taken along CC in FIG 17;

[0031] FIG19 is an enlarged view of point D in FIG18 .

[0032] Description of reference numerals:

[0033] 001, lower plastic part; 011, main body; 111, first surface; 1111a, clearance groove; 1111, first annular groove; 1112, second annular groove; 112, second surface; 113, reinforcing rib; 1131, first rib; 1132, second rib; 114, positioning rib; 115, guide rib; 116, positioning column; 117, through hole; 121, tapered surface; 012, first adhesive layer; 013, second adhesive layer; 002, top cover; 021, assembly surface; 003, upper plastic part; 004, terminal; 005, pole; 006, sealing ring. Modes for Carrying Out the Invention

[0034] In the description of this application, unless otherwise specified or limited, the terms "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0035] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0036] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0037] Example 1

[0038] This embodiment provides a lower plastic part 001, which is applied to a battery cell. The battery cell has an end cap assembly, a shell, an electrode assembly, and a busbar. The end cap assembly and the shell cover each other to form a storage cavity for storing electrolyte. The electrode assembly and the busbar are arranged in the storage cavity. The end cap assembly includes a top cover, a lower plastic part, and a pole. The pole piece of the electrode assembly is electrically connected to the pole via the busbar. The lower plastic part is configured to insulate the busbar from the top cap.

[0039] Specifically, as shown in FIG. 1 , the body 011 has a first surface 111 and a second surface 112 that are disposed opposite to each other. The first surface 111 is a plane and is configured to fit with the top cover.

[0040] The shape of the lower plastic part 001 is consistent with the shape of the cross-section of the battery cell. For example, when the battery cell is a square battery cell, the lower plastic part 001 is rectangular; when the battery cell is a cylindrical battery cell, the lower plastic part 001 is circular. When applied to the battery cell, the lower plastic part 001 can form surface-to-surface contact with the top cover after being attached to the top cover to avoid the electrolyte being stored between the two. In addition, the body 011 is provided with a through hole 117 that passes through the first surface 111 and the second surface 112. The through hole 117 includes but is not limited to a liquid injection hole, an explosion-proof valve exhaust hole, and a pole mounting hole. Among them, of the two through holes 117 shown in Figure 1, the through hole 117 located at the center of the lower plastic part 001 is a pole mounting hole, and the other through hole 117 is an explosion-proof valve exhaust hole.

[0041] Exemplarily, the roughness of the first surface 111 does not exceed Ra3.2. Specifically, the roughness of the first surface 111 may be Ra0.8.

[0042] In this embodiment, the first surface 111 where the lower plastic part 001 contacts the top cover is set to a planar structure so that the lower plastic part 001 is in contact with the top cover through the first surface 111. This can prevent the electrolyte from accumulating between the lower plastic part 001 and the top cover after the battery cell is inverted, thereby reducing the impact of the inversion of the battery cell on the immersion of the electrode assembly in the electrolyte, and ultimately improving the problem of insufficient wetting of the electrode assembly after the battery cell is inverted.

[0043] Furthermore, as shown in FIG2 and FIG3, the lower plastic part 001 further includes a first adhesive layer 012, which is arranged on the first surface 111 side around the periphery of the through hole 117, and the two sides of the first adhesive layer 012 are configured to be bonded to the top cover and the body 011 respectively.

[0044] It is understood that when the lower plastic part 001 is applied to a battery cell, the periphery of the lower plastic part 001 abuts against the inner wall of the battery cell's housing to form a sealed fit. Therefore, to improve the sealing between the top cover and the lower plastic part, a first adhesive layer 012 is provided at least around the circumference of the through hole 117.

[0045] Furthermore, to accommodate the structure of through-holes 117, first adhesive layer 012 has an annular structure. When lower plastic component 001 has multiple through-holes 117, first adhesive layer 012 is disposed around the periphery of each through-hole 117. Examples include injection holes, vent holes, and terminal mounting holes. First adhesive layer 012 is made of a glue that is non-reactive with the electrolyte. For example, the adhesive can be one or more of PVDF powder, styrene-butadiene rubber, polyacrylic acid, polyacrylonitrile, and polyurethane. Specifically, first adhesive layer 012 is HLi-T10 series sealant.

[0046] In this embodiment, a first adhesive layer 012 is disposed around the periphery of the through-hole 117, and both sides of the first adhesive layer 012 are bonded to the body 011 and the top cover, respectively. Thus, on the one hand, the first adhesive layer 012 can seal and isolate the contact area between the body 011 and the top cover from the through-hole 117, thereby preventing electrolyte from flowing between the lower plastic part 001 and the top cover after the battery cell is inverted, further reducing the impact of the inverted battery cell on the electrolyte soaking of the electrode assembly. On the other hand, the first adhesive layer 012 bonds the lower plastic part 001 to one side of the top cover, thereby improving the stability of the connection between the lower plastic part 001 and the top cover and preventing the lower plastic part 001 from shaking relative to the top cover.

[0047] 1 and 3 , a first annular groove 1111 is provided on the first surface 111 around the through hole 117 , the first adhesive layer 012 is provided in the first annular groove 1111 , and the side of the first adhesive layer 012 facing away from the second surface 112 is coplanar with the first surface 111 .

[0048] It will be understood that the first adhesive layer 012 is initially fluid, specifically glue, and fills the first annular groove 1111. After the lower plastic part 001 and the top cover are attached, the glue contacts the top cover. After the glue solidifies into an adhesive layer, the lower plastic part 001 and the top cover are bonded together, thereby sealing and isolating the contact area between the lower plastic part 001 and the top cover from the through-hole 117. Furthermore, if the lower plastic part 001 has multiple through-holes 117, a first annular groove 1111 is disposed around the periphery of each through-hole 117, and the first adhesive layer 012 is disposed in each annular groove.

[0049] Illustratively, the first annular groove 1111 is coaxially arranged with the corresponding through hole 117 .

[0050] In this embodiment, by providing the first annular groove 1111, the first adhesive layer 012 can be arranged along the first annular groove 1111. This, on the one hand, can control the amount of glue used and avoid glue waste; on the other hand, it can keep the first surface 111 and the top cover in a bonded state, and no gap will be formed between the top cover and the first surface 111 due to the provision of the first adhesive layer 012.

[0051] Furthermore, as shown in Figure 4 , the cross-section of the first annular groove 1111 in the thickness direction of the lower plastic component 001 can be any of the following: semicircular, V-shaped, U-shaped, or rectangular. It should be understood that this cross-section is a section through the first annular groove 1111 taken along the axial and radial planes of the lower plastic component 001. Specifically, the cross-section of the first annular groove 1111 is semicircular.

[0052] In this embodiment, by setting the cross-section of the first annular groove 1111 to a semicircular structure, on the one hand, the glue can better fill the first annular groove 1111, avoiding the existence of glue-left areas, thereby improving the sealing between the lower plastic part 001 and the top cover; on the other hand, the semicircular structure of the first annular groove 1111 can improve the uniformity of glue distribution, which helps to avoid glue concentration in a certain area.

[0053] Furthermore, as shown in FIG. 4 , the distance between the first surface 111 and the second surface 112 is D, and the depth of the first annular groove 1111 is d1 , which satisfies the following relationship: 10%D≤d1≤50%D.

[0054] It can be understood that d1 can be, but is not limited to, 10%D, 20%D, 40%D, or 50%D.

[0055] For example, when D=4 mm, 0.4 mm≤d1≤2 mm. Specifically, d1 may be, but is not limited to, 0.4 mm, 0.5 mm, 0.8 mm, 1 mm, 1.1 mm, 1.2 mm, 1.35 mm, 1.47 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, or 2 mm.

[0056] In this embodiment, by limiting the depth of the first annular groove 1111 as described above, the first annular groove 1111 can have a sufficient depth so that the first adhesive layer 012 can achieve a sealed connection between the lower plastic part 001 and the top cover; it can also ensure the strength of the lower plastic part 001 and avoid the situation where the depth of the first annular groove 1111 is too large, resulting in the strength of the lower plastic part 001 not meeting its working requirements.

[0057] Furthermore, as shown in Figures 4 and 7 , the diameter of the lower plastic part 001 is D0. Along the radial direction of the lower plastic part 001, the first annular groove 1111 has a width dimension W1 that satisfies the following: 1.5% D0 ≤ W1 ≤ 6.5% D0. It is understood that the diameter D0 of the lower plastic part 001 is the maximum diameter of the lower plastic part 001. W1 can be, but is not limited to, 1.5% D0, 2% D0, 4% D0, or 6.5% D0. For example, when D0 = 30 mm, 0.45 mm ≤ W1 ≤ 1.95 mm. Specifically, W1 can be, but is not limited to, 0.45 mm, 0.5 mm, 0.6 mm, 0.71 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.36 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, or 1.95 mm.

[0058] In this embodiment, by limiting the width of the first annular groove 1111 as described above, the first annular groove 1111 can have a sufficient width so that the first adhesive layer 012 can achieve a sealed connection between the lower plastic part 001 and the top cover; it can also ensure the strength of the lower plastic part 001 and avoid the situation where the width of the first annular groove 1111 is too large and the strength of the lower plastic part 001 does not meet its working requirements.

[0059] 3 , the spacing S between the inner periphery of the first annular groove 1111 and the periphery of the through hole 117 around which it is formed satisfies the following conditions: 1 mm ≤ S ≤ 5 mm. For example, S may be, but is not limited to, 1 mm, 1.15 mm, 1.3 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.88 mm, 1.9 mm, 2 mm, 2.1 mm, 2.3 mm, 2.9 mm, 3 mm, 3.62 mm, 4 mm, 4.2 mm, 4.5 mm, 4.8 mm, 4.9 mm, or 5 mm.

[0060] In this embodiment, by limiting the distance S between the inner periphery of the first annular groove 1111 and the periphery of the corresponding through hole 117 as described above, on the one hand, it is possible to avoid the glue in the first annular groove 1111 overflowing and contaminating the pole or the explosion-proof valve due to the distance S being too small; on the other hand, it is possible to avoid the electrolyte flowing into between the lower plastic part 001 and the top cover due to the distance S being too large.

[0061] Furthermore, as shown in Figure 5, lower plastic component 001 also includes a second adhesive layer 013. Second adhesive layer 013 is disposed around the perimeter of first surface 111, with two sides of second adhesive layer 013 configured to bond to the top cover and body 011, respectively. It is understood that second adhesive layer 013 has an annular structure and can be made of the same material as first adhesive layer 012. For example, second adhesive layer 013 can be HLi-T10 series sealant.

[0062] In this embodiment, a second adhesive layer 013 is disposed around the periphery of the first surface 111, with both sides of the second adhesive layer 013 adhesively bonded to the body 011 and the top cover. This allows, on the one hand, the second adhesive layer 013 to seal and isolate the contact area between the body 011 and the top cover from the periphery of the lower plastic component 001, thereby preventing electrolyte from flowing into the gap between the lower plastic component 001 and the top cover when the battery cell is inverted. Furthermore, the second adhesive layer 013 adhesively bonds the lower plastic component 001 to one side of the top cover, thereby enhancing the stability of the connection between the lower plastic component 001 and the top cover and preventing the lower plastic component 001 from shaking relative to the top cover.

[0063] Furthermore, as shown in FIG5 , a second annular groove 1112 is provided around the periphery of the first surface 111. A second adhesive layer 013 is disposed within the second annular groove 1112, with the side of the second adhesive layer 013 facing away from the second surface 112 being coplanar with the first surface 111. It will be appreciated that, like the first adhesive layer 012, the second adhesive layer 013 is initially fluid and fills the second annular groove 1112. After the lower plastic part 001 and the top cover are joined together, the glue contacts the top cover. The glue solidifies to form the second adhesive layer 013, bonding the lower plastic part 001 and the top cover together, thereby sealing and isolating the joint between the body 011 and the top cover from the through hole 117. Exemplarily, the second annular groove 1112 is coaxial with the lower plastic part 001.

[0064] In this embodiment, by providing the second annular groove 1112, the second adhesive layer 013 can be disposed along the second annular groove 1112. This not only controls the amount of glue used, thus avoiding glue waste, but also maintains the first surface 111 and the top cover in contact with each other, eliminating any gap between the top cover and the first surface 111 due to the second adhesive layer 013.

[0065] Furthermore, the cross-section of the second annular groove 1112 in the thickness direction of the lower plastic part 001 can be any of the following: semicircular, V-shaped, U-shaped, or rectangular. It will be understood that, like the first annular groove 1111, the cross-section of the second annular groove 1112 is a section of the second annular groove 1112 taken along the axial and radial planes of the lower plastic part 001. Specifically, the cross-section of the second annular groove 1112 is semicircular.

[0066] In this embodiment, by setting the cross-section of the second annular groove 1112 to a semicircular structure, on the one hand, the glue can better fill the second annular groove 1112, avoiding the existence of glue-left areas, thereby improving the sealing between the lower plastic part 001 and the top cover; on the other hand, the semicircular structure of the second annular groove 1112 can improve the uniformity of glue distribution, which helps to avoid glue concentration in a certain area.

[0067] Furthermore, as shown in FIG6 , the distance between the first surface 111 and the second surface 112 is D, and the depth of the second annular groove 1112 is d2, satisfying the following: 10% D ≤ d2 ≤ 50% D. It is understood that d2 may be, but is not limited to, 10% D, 20% D, 40% D, or 50% D. For example, when D = 4 mm, 0.4 mm ≤ d2 ≤ 2 mm. Specifically, d2 may be, but is not limited to, 0.4 mm, 0.47 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.15 mm, 1.2 mm, 1.39 mm, 1.4 mm, 1.5 mm, 1.67 mm, 1.68 mm, 1.7 mm, 1.8 mm, 1.9 mm, or 2 mm.

[0068] In this embodiment, by limiting the depth of the second annular groove 1112 as described above, the second annular groove 1112 can have a sufficient depth so that the second adhesive layer 013 can achieve a sealed connection between the lower plastic part 001 and the top cover; it can also ensure the strength of the lower plastic part 001 and avoid the situation where the depth of the second annular groove 1112 is too large and the strength of the lower plastic part 001 does not meet its working requirements.

[0069] Furthermore, as shown in FIG6 , the diameter of the lower plastic part 001 is D0. Along the radial direction of the lower plastic part 001, the second annular groove 1112 has a width dimension W2 that satisfies: 1.5% D0 ≤ W2 ≤ 6.5% D0. It is understood that W2 may be, but is not limited to, 1.5% D0, 2% D0, 4% D0, or 6.5% D0. For example, when D0 = 30 mm, 0.45 mm ≤ W2 ≤ 1.95 mm. Specifically, W2 may be, but is not limited to, 0.45 mm, 0.5 mm, 0.56 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.55 mm, 1.6 mm, 1.89 mm, or 1.95 mm.

[0070] In this embodiment, by limiting the width of the second annular groove 1112 as described above, the second annular groove 1112 can have a sufficient width so that the second adhesive layer 013 can achieve a sealed connection between the lower plastic part 001 and the top cover; it can also ensure the strength of the lower plastic part 001 and avoid the situation where the width of the second annular groove 1112 is too large, resulting in the strength of the lower plastic part 001 not meeting its working requirements.

[0071] 7 , the second surface 112 is provided with positioning ribs 114 , which are configured to engage with the busbar of the battery cell. The positioning ribs 114 can position the busbar to prevent it from rotating.

[0072] 1 , the first surface 111 is provided with a plurality of positioning posts 116 , which are configured to be plugged into the top cover. For example, the positioning posts 116 are integrally formed with the body 011 and are cylindrical.

[0073] In this embodiment, by providing a positioning post 116 on the first surface 111 to engage with the top cover, the lower plastic part 001 can be prevented from rotating relative to the top cover, thereby improving the position stability of the lower plastic part 001 relative to the top cover and further improving the structural stability of the battery cell.

[0074] As shown in FIG. 8 and FIG. 9 , this embodiment further provides an end cover assembly.

[0075] Specifically, the end cover assembly includes a top cover 002, an upper plastic part 003, a terminal 004, a pole 005 and the aforementioned lower plastic part 001, the first surface 111 contacts one side of the top cover 002; the upper plastic part 003 contacts the other side of the top cover 002; the terminal 004 is located on the side of the upper plastic part 003 facing away from the top cover 002; one end of the pole 005 passes through the lower plastic part 001, the top cover 002 and the upper plastic part 003 in sequence and is connected to the terminal 004. Specifically, the pole 005 is inserted into the terminal 004.

[0076] It can be understood that the hole in terminal 004 for pole 005 to insert is a stepped hole, with the large-diameter section located on the side of terminal 004 facing away from top cover 002. Pole 005 is a stepped shaft, with its large-diameter section located on the side of lower plastic part 001 facing away from top cover 002. The end of its small-diameter section passes through lower plastic part 001, top cover 002, upper plastic part 003, and the stepped hole in sequence. Pressing down on the small-diameter section causes it to expand radially toward the wall of the large-diameter section, allowing pole 005 to engage the bottom stop of the large-diameter section. This then rivets lower plastic part 001, top cover 002, upper plastic part 003, and terminal 004 together through pole 005. In addition, a sealing ring 006 is provided between pole 005 and top cover 002.

[0077] In conjunction with the previous embodiment, both the first adhesive layer 012 and the second adhesive layer 013 are bonded to the top cover 002, as shown in Figures 10 and 11. In Figure 10, the first adhesive layer 012 on the left side is disposed around the through hole 117 on the lower plastic part 001 for the pole 005 to pass through, while the first adhesive layer 012 on the right side is disposed around the through hole 117 on the lower plastic part 001 for venting. In Figure 11, the first adhesive layer 012 is disposed around the through hole 117 on the lower plastic part 001 for venting, while the second adhesive layer 013 is disposed around the periphery of the first surface 111.

[0078] In this embodiment, the first surface 111 of the lower plastic part 001 is flat, and a first annular groove 1111 and a second annular groove 1112 are provided on the first surface 111. Glue is then applied to the annular grooves. Subsequently, the lower plastic part 001 and the top cover 002 are riveted together to bond the lower plastic part 001 and the top cover 002. This seals the space between the lower plastic part 001 and the top cover 002 from the outside, thereby preventing electrolyte from entering the space between the lower plastic part 001 and the top cover 002. This prevents liquid from accumulating between the lower plastic part 001 and the top cover 002, thereby reducing the impact of an inverted battery cell on the electrolyte soaking of the electrode assembly. Ultimately, this improves the problem of insufficient electrode assembly wetting after an inverted battery cell.

[0079] Example 2

[0080] Typically, when the end cap assembly is pressed into the housing, the lower plastic part 001 compresses the electrode assembly axially along the battery cell. Simultaneously, the electrode assembly exerts a reaction force on the lower plastic part 001. Because the lower plastic part 001 is constrained on both sides by the top cap and the electrode assembly, the axial pressure causes the lower plastic part 001 to expand radially, squeezing the housing opening and causing deformation, which hinders the welding of the housing and the top cap.

[0081] Based on this, this embodiment provides a lower plastic part 001 based on the first embodiment. The lower plastic part 001 in this embodiment is different from the lower plastic part 001 provided in the first embodiment in that:

[0082] As shown in Figures 12 and 13, the first surface 111 is configured to contact the top cover 002. A clearance groove 1111a is provided on the circumference of the first surface 111. The clearance groove 1111a extends along at least a portion of the circumference of the first surface 111. It can be understood that the clearance groove 1111a can extend along a portion of the circumference of the first surface 111, or can extend along the entire circumference as an annular groove. In addition, the lower plastic part 001 is an insulating part, which is used to insulate and isolate the electrode assembly from the top cover 002. The shape of the lower plastic part 001 is consistent with the shape of the cross-section of the battery cell. For example, when the battery cell is a square battery cell, the lower plastic part 001 is rectangular; when the battery cell is a cylindrical battery cell, the lower plastic part 001 is circular.

[0083] In this embodiment, by providing a clearance groove 1111a on the circumference of the first surface 111, a spacing is created between the lower plastic part 001 and the top cover 002 at their peripheries, providing space for axial deformation of the periphery of the lower plastic part 001. Consequently, when the end cap assembly is pressed into the housing, the lower plastic part 001 exerts axial pressure on the electrode assembly. Based on this axial pressure, the electrode assembly generates an axial reaction force on the lower plastic, causing the circumferential edge of the lower plastic part 001 to press against the clearance groove 1111a, thereby reducing radial deformation of the lower plastic part 001 and, in turn, the squeezing force on the shell opening when the lower plastic part 001 is inserted into the housing. Ultimately, this reduces deformation of the shell opening and facilitates welding between the housing and the top cover 002.

[0084] Furthermore, once the lower plastic part 001 is fully assembled, it recovers its deformation and maintains contact with the inner wall of the housing, sealing the interior of the housing. At this point, the lower plastic part 001 is offset from the housing opening along the axial direction of the battery cell. Therefore, once fully assembled, the lower plastic part 001 does not squeeze the housing opening. Furthermore, once the lower plastic part 001 is fully assembled, the clearance groove 1111a creates a gap between the perimeter of the first surface 111 and the welding surface of the top cover 002, thereby reducing the impact of the high welding temperature between the top cover 002 and the housing on the lower plastic part 001.

[0085] 14 , optionally, the clearance groove 1111a is an annular groove. It is understood that the clearance groove 1111a is an annular groove extending 360° along the circumference of the first surface 111. Exemplarily, the clearance groove 1111a is coaxial with the lower plastic part 001.

[0086] In this embodiment, by configuring the relief groove 1111a as an annular groove, when the end cap assembly is pressed into the housing, the electrode assembly generates an axial reaction force on the lower plastic, causing the circumference of the lower plastic part 001 to be squeezed toward the relief groove 1111a. This reduces the overall radial deformation of the lower plastic part 001, further reducing the squeezing force on the housing opening when the lower plastic part 001 is inserted into the housing. This further reduces deformation of the housing opening.

[0087] In addition, a gap exists between the entire periphery of the first surface 111 and the entire welding surface of the top cover 002 due to the clearance groove 1111 a, thereby further improving the influence of the high welding temperature between the top cover 002 and the shell on the lower plastic component 001 .

[0088] Please refer to Figure 15. Further, the clearance groove 1111a includes a first groove wall and a second groove wall. One side of the first groove wall is connected to the first surface 111, and the other side is connected to one side of the second groove wall. The other side of the second groove wall is connected to the outer peripheral surface of the body 011. Among the connection between the first surface and the first groove wall, the connection between the first groove wall and the second groove wall, and the connection between the second groove wall and the outer peripheral surface of the body, at least one connection is rounded. It can be understood that the clearance groove 1111a is a V-shaped groove. Exemplarily, the first groove wall is perpendicular to the second groove wall. The first groove wall is a cylindrical arc surface, and its axis is collinear with the axis of the lower plastic part 001. The axis of the lower plastic part 001 is perpendicular to the second groove wall. In addition, the above three connections are all rounded.

[0089] In this embodiment, through the above arrangement, on the one hand, the axial deformation space of the periphery of the lower plastic part 001 can be provided by the clearance groove 1111a; on the other hand, the overall structure of the clearance groove 1111a is simple and easy to manufacture.

[0090] In addition, by rounding the corners at the connection, the stress at the connection can be reduced when the periphery of the lower plastic part 001 is axially deformed, thereby improving the stress state of the lower plastic part 001 and increasing the service life of the lower plastic part 001.

[0091] Please refer to FIG. 15 . Furthermore, along the radial direction of the lower plastic component 001 , the clearance groove 1111 a has a first size B, which satisfies: 0<B≤2 mm.

[0092] It is understood that the first dimension B can be, but is not limited to, 0.1mm, 0.2mm, 0.26mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.77mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.45mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 1.95mm, or 2mm. Based on different processing accuracies, the first dimension B can be configured with different minimum values. For example, when the minimum precision of the molded plastic part 001 is 0.05mm, the minimum value of the first dimension B can be 0.05mm. When the minimum precision of the molded plastic part 001 is 0.1mm, the minimum value of the first dimension B can be 0.1mm.

[0093] In this embodiment, by limiting the first dimension B, on the one hand, space is provided for axial deformation of the periphery of the lower plastic part 001; on the other hand, the strength of the lower plastic part 001 is ensured, preventing the first dimension B from being too large, which would result in insufficient strength at the periphery of the lower plastic part 001. Thus, the lower plastic part 001 can meet the working conditions required.

[0094] Exemplarily, 0.1 mm ≤ B ≤ 1 mm. Further, 0.1 mm ≤ B ≤ 0.5 mm.

[0095] Please refer to FIG. 15 . Furthermore, along the axial direction of the lower plastic component 001 , the clearance groove 1111 a has a second dimension C, satisfying: 0<C≤2 mm.

[0096] It can be understood that in order to ensure the groove structure of the give way groove 1111a, the second dimension C does not pass through the lower plastic part 001. Therefore, different maximum limits can be made for the second dimension C according to the different sizes of the lower plastic part 001. The second dimension C can be, but is not limited to, 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1.2mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 1.95mm, and 2mm. Based on different processing accuracies, the second dimension C can be configured with different minimum values. For example, when the minimum precision of the mold forming the lower plastic part 001 is 0.05mm, the minimum value of the second dimension C can be 0.05mm. When the minimum precision of the mold forming the lower plastic part 001 is 0.1mm, the minimum value of the second dimension C can be 0.1mm. Exemplarily, 0.1mm≤C≤1mm.

[0097] In this embodiment, by limiting the second dimension C, space is provided for axial deformation of the periphery of the lower plastic part 001. Furthermore, the strength of the lower plastic part 001 is ensured, preventing the second dimension C from being too large, which would result in insufficient strength at the periphery of the lower plastic part 001. Thus, the lower plastic part 001 meets the working conditions required.

[0098] Please refer to FIG. 15 . Further, along the periphery of the body 011 , the second surface 112 is provided with a guide rib 115 . The outer peripheral surface of the guide rib 115 is a conical surface 121 , and the large diameter end of the conical surface 121 is connected to the second surface 112 .

[0099] It can be understood that when the end cover assembly is pressed into the housing, the small diameter end of the conical surface 121 faces the interior of the battery cell.

[0100] In addition, the distance between the first surface 111 and the second surface 112 is D, and C≤D.

[0101] In this embodiment, by providing a guide rib 115 with a conical surface 121 on its outer circumference, the end cover assembly can be guided when entering the shell by the conical surface 121 of the guide rib 115, and a gap can be formed between the conical surface 121 and the inner wall of the shell to provide space for the radial deformation of the guide rib 115, thereby preventing the guide rib 115 from squeezing the shell opening.

[0102] Please refer to FIG. 15 . Furthermore, the inclination angle of the conical surface 121 is E, which satisfies: 5°≤E≤60°.

[0103] It is understood that the inclination angle E can be, but is not limited to, 1°, 5°, 10°, 15°, 18°, 20°, 25°, 29°, 30°, 31°, 33.6°, 36°, 37°, 40°, 42°, 45°, 48°, 50°, 52°, 55°, 56.2°, 59°, or 60°. For example, 5° ≤ E ≤ 45°. Furthermore, 15° ≤ E ≤ 30°.

[0104] In this embodiment, by limiting the inclination angle E, space can be provided for the radial deformation of the guide rib 115 to prevent the lower plastic part 001 from being squeezed against the shell opening after being resisted by the electrode assembly; the strength of the guide rib 115 can be ensured to avoid the inclination angle E being too large, which may lead to the guide rib 115 having too low strength, thereby allowing the lower plastic part 001 to meet the working conditions.

[0105] Please refer to FIG. 15 . Furthermore, one end of the guide rib 115 close to the main body 011 at least partially forms a groove wall of the clearance groove 1111 a .

[0106] In this embodiment, by partially forming the walls of the relief groove 1111a with the guide rib 115, the thickness of the lower plastic part 001 at the periphery is reduced, thereby reducing the strength at the periphery. As a result, when the end cap assembly is pressed into the housing, the edge of the lower plastic part 001 is easily squeezed toward the relief groove 1111a.

[0107] Furthermore, the second surface 112 is coplanar with an end of the guide rib 012 close to the body 011 .

[0108] It can be understood that the second side wall is formed on the guide rib 115 .

[0109] In this embodiment, the second surface 112 and the end of the guide rib 115 close to the body 011 are coplanar, so that the structure of the lower plastic component 001 is simple and easy to manufacture.

[0110] Referring to Figure 16, further, the second surface 112 is provided with a plurality of reinforcing ribs 113. The reinforcing ribs 113 are integrally formed with the body 011, for example, by integral injection molding. There are four reinforcing ribs 113, and they are spaced apart along the periphery of the lower plastic part 001. Specifically, the reinforcing ribs 113 include a first rib 1131 and a second rib 1132. The first rib 1131 is provided to extend radially along the lower plastic part 001. The second rib 1132 is an arc-shaped rib. The inner concave surface of the second rib faces the axial direction of the lower plastic part 001. The outer convex surface of the second rib is connected to the end of the first rib 1131 close to the axis of the lower plastic part 001.

[0111] In this embodiment, the provision of reinforcing ribs 113 strengthens the lower plastic part 001 in both radial and circumferential directions, thereby enhancing the overall strength of the lower plastic part 001. Furthermore, the provision of reinforcing ribs 113 increases the elasticity of the lower plastic part 001, providing it with more flexibility to press against the electrode assembly and restrict its movement. The reinforcing ribs 113 are not planarly connected to each other to avoid forming a semi-enclosed structure. This facilitates the smooth flow of electrolyte after entering between the reinforcing ribs 113, without affecting electrolyte flow.

[0112] The remaining structures of the lower plastic part 001 provided in this embodiment are the same as those in the first embodiment and will not be described in detail.

[0113] Please refer to Figures 17 and 18. Accordingly, an embodiment of the present application also provides an end cover assembly, which includes a top cover 002, an upper plastic part 003, a terminal 004, a pole 005 and the aforementioned lower plastic part 001. The first surface 111 contacts one side of the top cover 002; the upper plastic part 003 contacts the other side of the top cover 002; the terminal 004 is located on the side of the upper plastic part 003 away from the top cover 002; one end of the pole 005 passes through the lower plastic part 001, the top cover 002 and the upper plastic part 003 in sequence and is connected to the terminal 004. Specifically, one end of the pole 005 is inserted into the terminal 004.

[0114] It can be understood that the hole in terminal 004 for pole 005 to insert is a stepped hole, with the large-diameter section located on the side of terminal 004 facing away from top cover 002. Pole 005 is a stepped shaft, with its large-diameter section located on the side of lower plastic part 001 facing away from top cover 002. The end of its small-diameter section passes through lower plastic part 001, top cover 002, upper plastic part 003, and the stepped hole in sequence. Pressing down on the small-diameter section causes it to expand radially toward the wall of the large-diameter section, allowing pole 005 to engage the bottom stop of the large-diameter section. This then rivets lower plastic part 001, top cover 002, upper plastic part 003, and terminal 004 together through pole 005. In addition, a sealing ring 006 is provided between pole 005 and top cover 002.

[0115] In this embodiment, when the end cap assembly is pressed into the housing, the lower plastic component 001 squeezes the electrode assembly and is subjected to a reverse force from the electrode assembly, causing the lower plastic component 001 to be axially compressed. This causes the peripheral edge of the lower plastic component 001 to deform toward the relief groove 1111a, converting the radial expansion of the lower plastic component 001 after compression into axial deformation. This prevents the end cap assembly from squeezing the housing opening when inserted, thereby facilitating smooth welding between the housing and the top cover 002.

[0116] Please refer to FIG. 18 and FIG. 19 . Furthermore, the top cover 002 has an assembly surface 021 . There is a distance L between the assembly surface 021 and the outer peripheral surface of the lower plastic component 001 , which satisfies: 0≤L≤3mm.

[0117] It can be understood that the assembly surface 021 is the surface on the top cover 002 that circumferentially fits against the inner wall of the housing. The spacing L can be, but is not limited to, 0.1mm, 0.3mm, 0.4mm, 0.46mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.94mm, 1mm, 1.1mm, 1.2mm, 1.26mm, 1.3mm, 1.4mm, 1.5mm, 1.62mm, 1.7mm, 1.85mm, 1.9mm, 2mm, 2.2mm, 2.5mm, 2.61mm, 2.7mm, 2.8mm, 2.9mm, or 3mm.

[0118] In this embodiment, by limiting the distance L, it is possible to avoid the electrode assembly from contacting the top cover 002 when the distance L is too large, thereby ensuring the working stability of the battery cell.

[0119] Furthermore, in conjunction with the foregoing, it can be understood that during the process of pressing the end cap assembly into the housing, the lower plastic part 001 squeezes the electrode assembly, and the electrode assembly exerts a reaction force on the lower plastic part 001. Because the first surface 111 includes a relief groove 1111a, the reaction force exerted by the electrode assembly on the lower plastic part 001 causes the peripheral edge of the lower plastic part 001 to deform toward the relief groove 1111a, thereby preventing radial expansion of the lower plastic part 001 due to the compression, and thus preventing the lower plastic part 001 from squeezing the housing opening. Based on this, when the relief groove 1111a is provided on the lower plastic part 001, the peripheral edge of the lower plastic part 001 deforms toward the relief groove 1111a, without squeezing the housing opening. In this way, the outer diameter of the lower plastic part 001 can be consistent with the diameter of the assembly surface 021, that is, the outer diameter of the lower plastic part 001 can be consistent with the inner diameter of the housing opening. Therefore, the distance L between the assembly surface 021 and the outer peripheral surface of the lower plastic component 001 may be zero.

[0120] In order to further reduce the extrusion of the shell opening, illustratively, 0.1mm≤L≤2mm. Further, 0.2≤L≤1mm. Optionally, L=0.4mm.

[0121] Furthermore, the coaxiality tolerance between the lower plastic part 001 and the top cover 002 is A, satisfying: A≤L≤3mm.

[0122] For example, the coaxiality tolerance satisfies: 0≤A≤0.3mm. The coaxiality tolerance A can be, but is not limited to, 0.1mm, 0.2mm, or 0.3mm. When A=0.3mm, 0.3mm≤L≤3mm.

[0123] In this embodiment, by limiting the spacing L between the lower plastic part 001 and the top cover 002 by the coaxiality tolerance A between the lower plastic part 001 and the top cover 002, when the axial offset distance between the lower plastic part 001 and the top cover 002 is maximum (the maximum axial offset distance is A), the outer periphery of the lower plastic part 001 can be prevented from exceeding the assembly surface 021 of the top cover 002, thereby improving the squeezing of the plastic part on the shell opening when the end cover assembly is pressed into the shell.

[0124] Accordingly, this embodiment also provides a battery cell, which includes the aforementioned end cap assembly. Exemplarily, the battery cell is a cylindrical battery cell. It can be understood that the battery cell also includes a shell, a bottom cover assembly, an electrode assembly, a positive electrode busbar, and a negative electrode busbar. The shell has a first opening and a second opening that are relatively arranged. The end cap assembly is covered with the first opening, and the bottom cap assembly is covered with the second opening. The electrode assembly is arranged in the shell, and its positive electrode tab is connected to the positive electrode column 005 of the top cover 002 assembly through the positive electrode busbar, and the negative electrode tab is connected to the bottom cover assembly through the negative electrode busbar.

Claims

1. A lower plastic part, applied to a battery cell, wherein the battery cell has a top cover, and the lower plastic part comprises: The body comprises a first surface and a second surface which are arranged opposite to each other, wherein the first surface (111) is a plane and is arranged to fit with the top cover (002).

2. The lower plastic part according to claim 1, wherein: The body (011) is provided with a through hole (117) penetrating the first surface (111) and the second surface (112).

3. The lower plastic part according to claim 2, wherein: The lower plastic part further comprises a first adhesive layer (012), the first adhesive layer (012) being arranged on the first surface (111) side around the periphery of the through hole (117), and the two sides of the first adhesive layer (012) being configured to be respectively bonded to the top cover (002) and the body (011).

4. The lower plastic part according to claim 3, wherein: The first surface (111) is provided with a first annular groove (1111) around the through hole (117); the first adhesive layer (012) is provided in the first annular groove (1111); and a side of the first adhesive layer (012) facing away from the second surface (112) is coplanar with the first surface (111).

5. The lower plastic part according to claim 4, wherein: In the thickness direction of the lower plastic part, the cross-section of the first annular groove (1111) is in any one of the following shapes: semicircular, V-shaped, U-shaped, or rectangular.

6. The lower plastic part according to claim 4 or 5, wherein: The distance between the first surface (111) and the second surface (112) is D, and the depth of the first annular groove (1111) is d1, satisfying: 10%D≤d1≤50%D.

7. The lower plastic part according to claim 4 or 5, wherein: The diameter of the lower plastic part is D0. Along the radial direction of the lower plastic part, the first annular groove (1111) has a width dimension W1, which satisfies: 1.5%D0≤W1≤6.5%D0.

8. The lower plastic part according to claim 4 or 5, wherein: The distance between the inner periphery of the first annular groove (1111) and the periphery of the through hole (117) around which it is arranged is S, satisfying: 1mm≤S≤5mm.

9. The lower plastic part according to any one of claims 1 to 8, wherein: The lower plastic part further comprises a second adhesive layer (013), the second adhesive layer (013) being arranged around the periphery of the first surface (111), and two sides of the second adhesive layer (013) being configured to be respectively bonded to the top cover (002) and the body (011).

10. The lower plastic part according to claim 9, wherein: A second annular groove (1112) is arranged at the periphery of the first surface (111), the second adhesive layer (013) is arranged in the second annular groove (1112), and a side of the second adhesive layer (013) facing away from the second surface (112) is coplanar with the first surface (111).

11. The lower plastic part according to claim 10, wherein: In the thickness direction of the lower plastic part, the cross-sectional shape of the second annular groove (1112) is any one of the following shapes: semicircular, V-shaped, U-shaped, rectangular.

12. The lower plastic part according to claim 10 or 11, wherein: The distance between the first surface (111) and the second surface (112) is D, and the depth of the second annular groove (1112) is d2, satisfying: 10%D≤d2≤50%D.

13. The lower plastic part according to claim 10 or 11, wherein: The diameter of the lower plastic part is D0. Along the radial direction of the lower plastic part, the second annular groove (1112) has a width dimension W2, satisfying: 1.5%D0≤W2≤6.5%D0.

14. The lower plastic part according to any one of claims 1 to 13, wherein: The second surface (112) is provided with positioning ribs (114), and the positioning ribs (114) are configured to be clamped with the busbar of the battery cell.

15. The lower plastic part according to any one of claims 1 to 14, wherein: A clearance groove (1111a) is provided on the circumference of the first surface (111), and the clearance groove (1111a) extends at least along a portion of the circumference of the first surface (111).

16. The lower plastic part according to claim 15, wherein: The clearance groove (1111a) is an annular groove.

17. The lower plastic part according to claim 15, wherein: The give way groove (1111a) comprises a first groove wall and a second groove wall, one side of the first groove wall is connected to the first surface (111), the other side is connected to one side of the second groove wall, and the other side of the second groove wall is connected to the outer peripheral surface of the body (011).

18. The lower plastic part according to claim 17, wherein: At least one of the connections between the first surface (111) and the first groove wall, the connection between the first groove wall and the second groove wall, and the connection between the second groove wall and the outer peripheral surface of the body (011) has a rounded corner.

19. The lower plastic part according to any one of claims 15 to 18, wherein: Along the radial direction of the lower plastic part, the clearance groove (1111a) has a first size B, satisfying: 0<B≤2mm.

20. The lower plastic part according to any one of claims 15 to 18, wherein: Along the axial direction of the lower plastic part, the clearance groove (1111a) has a second size C, satisfying: 0<C≤2mm.

21. According to the lower plastic part according to any one of claims 15 to 18, a guide rib (115) is provided on the second surface (112) along the periphery of the body (011), the outer peripheral surface of the guide rib (115) is a conical surface (121), and the large diameter end of the conical surface (121) is connected to the second surface (112).

22. The lower plastic part according to claim 21, wherein: The inclination angle of the conical surface (121) is E, which satisfies: 5°≤E≤60°.

23. The lower plastic part according to claim 21, wherein: One end of the guide rib (115) close to the main body (011) at least partially forms a groove wall of the clearance groove (1111a).

24. The lower plastic part according to claim 23, wherein: The second surface (112) is coplanar with an end of the guide rib (115) close to the main body (011).

25. The lower plastic part according to any one of claims 1 to 24, wherein the second surface (112) is provided with a plurality of reinforcing ribs (113).

26. The lower plastic part according to claim 25, wherein: A plurality of reinforcing ribs (113) are arranged at intervals along the periphery of the lower plastic part.

27. The lower plastic member according to claim 25, wherein: The reinforcing rib (113) comprises a first rib (1131) and a second rib (1132); the first rib (1131) is arranged to extend radially along the lower plastic part; the second rib (1132) is an arc-shaped rib, the inner concave surface of the second rib (1132) faces the axial direction of the lower plastic part, and the outer convex surface of the second rib (1132) is connected to an end of the first rib (1131) close to the axial direction of the lower plastic part.

28. An end cover assembly, comprising a top cover (002), an upper plastic part (003), a terminal (004), a pole (005) and a lower plastic part as described in any one of claims 1 to 27, wherein the first surface (111) contacts one side of the top cover (002); the upper plastic part (003) contacts the other side of the top cover (002); the terminal (004) is located on a side of the upper plastic part (003) facing away from the top cover (002); one end of the pole (005) passes through the lower plastic part, the top cover (002) and the upper plastic part (003) in sequence and is connected to the terminal (004).

29. The end cover assembly according to claim 28, wherein the top cover (002) has a mounting surface (021), and a spacing L is provided between the mounting surface (021) and the outer peripheral surface of the lower plastic part, satisfying: 0≤L≤3mm.

30. The end cap assembly of claim 29, wherein: The coaxiality tolerance between the lower plastic part and the top cover (002) is A, satisfying: A≤L≤3mm.

31. The end cap assembly of claim 30, wherein: The coaxiality tolerance A satisfies: 0≤A≤0.3mm.

32. A battery cell comprising the end cap assembly according to any one of claims 28 to 31.

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